JP6269484B2 - Field effect passivation layer forming composition, semiconductor substrate with field effect passivation layer, method for manufacturing semiconductor substrate with field effect passivation layer, solar cell element, method for manufacturing solar cell element, and solar cell - Google Patents

Description

The present invention, field-effect passivation layer forming composition, a semiconductor substrate with field effect passivation layer, a method of manufacturing a semiconductor substrate with field effect passivation layer, a solar cell element, a manufacturing method and a solar cell of the solar cell element.

The manufacturing process of the conventional silicon solar cell element is demonstrated.
First, a p-type silicon substrate having a texture structure formed on the light-receiving surface side is prepared so as to promote the light confinement effect and increase the efficiency, and then in a mixed gas atmosphere of phosphorus oxychloride (POCl ₃ ), nitrogen and oxygen An n-type diffusion layer is uniformly formed by performing several tens of minutes at 800 ° C. to 900 ° C. In this conventional method, since phosphorus is diffused using a mixed gas, n-type diffusion layers are formed not only on the front surface, which is the light receiving surface, but also on the side surface and the back surface. Therefore, side etching is performed to remove the n-type diffusion layer formed on the side surface. Further, the n-type diffusion layer formed on the back surface needs to be converted into a p ⁺ -type diffusion layer. For this reason, an aluminum paste is applied to the entire back surface, and this is heat-treated (fired), thereby forming an aluminum electrode together with the ohmic contact by converting the n-type diffusion layer into the p ⁺ -type diffusion layer. It has gained.

  However, the electrical conductivity of the aluminum electrode formed from the aluminum paste is low. Therefore, in order to reduce the sheet resistance, the aluminum electrode formed on the entire back surface usually must have a thickness of about 10 μm to 20 μm after heat treatment (firing). Furthermore, since the coefficient of thermal expansion differs greatly between silicon and aluminum, a large internal stress is generated in the silicon substrate during the heat treatment (firing) and cooling in the silicon substrate on which the aluminum electrode is formed, and the grain boundary Cause damage, crystal defect growth and warpage.

In order to solve this problem, there is a method of reducing the applied amount of the aluminum paste and reducing the thickness of the back electrode layer. However, if the applied amount of the aluminum paste is reduced, the amount of aluminum diffusing from the surface of the p-type silicon semiconductor substrate becomes insufficient. As a result, the desired BSF (Back Surface Field) effect (the effect of improving the collection efficiency of the generated carriers due to the presence of the p ⁺ -type diffusion layer) cannot be achieved, resulting in a problem that the characteristics of the solar cell deteriorate. .

In relation to the above, a point contact method has been proposed in which an aluminum paste is applied to a part of the surface of a silicon substrate to partially form a p ⁺ -type diffusion layer and an aluminum electrode (for example, Japanese Patent No. 3107287). See the official gazette).
In the case of a solar cell having a point contact structure on the surface opposite to the light receiving surface (hereinafter also referred to as “back surface”), it is necessary to suppress the recombination rate of minority carriers on the surface of the portion other than the aluminum electrode. is there. For this purpose, a SiO ₂ film or the like has been proposed as a passivation layer for the back surface (see, for example, JP-A-2004-6565). As a passivation effect by forming such a SiO ₂ film, there is an effect of terminating the dangling bonds of silicon atoms in the surface layer portion on the back surface of the silicon substrate, and reducing the surface state density causing recombination. .

As another method of suppressing recombination of minority carriers, there is a method of reducing the minority carrier density by an electric field that generates fixed charges in the passivation layer. Such a passivation effect is generally called a field effect, and an aluminum oxide (Al ₂ O ₃ ) film or the like has been proposed as a material having a negative fixed charge (see, for example, Japanese Patent No. 4767110).
Such a passivation layer is generally formed by a method such as an ALD (Atomic Layer Deposition) method or a CVD (Chemical Vapor Deposition) method (for example, Journal of Applied Physics, 104 (2008), 113703-1 to 113703-7). As a simple method for forming an aluminum oxide film on a semiconductor substrate, a sol-gel method has been proposed (for example, Thin Solid Films, 517 (2009), 6327-6330, and Chinese Physics Letters, 26 (2009)). , 088102-1-088102-4).

  Since the technique described in Journal of Applied Physics, 104 (2008), 113703-1 to 113703-7 includes a complicated manufacturing process such as vapor deposition, it may be difficult to improve productivity. In addition, the composition for forming a passivation layer used in the methods described in Thin Solid Films, 517 (2009), 6327-6330, and Chinese Physics Letters, 26 (2009), 088102-1-088102-4, It is difficult to say that the storage stability is sufficient because of problems such as crystallization. In addition, a passivation layer having an excellent passivation effect using an oxide containing a metal element other than aluminum has not been sufficiently studied so far.

  The present invention has been made in view of the above-described conventional problems, and can form a passivation layer having a desired shape by a simple method, and has excellent storage stability and coating film uniformity. It is an object to provide a forming composition. Another object of the present invention is to provide a semiconductor substrate with a passivation layer, a solar cell element and a solar cell using the composition for forming a passivation layer. Furthermore, this invention makes it a subject to provide the manufacturing method of a semiconductor substrate with a passivation layer and a solar cell element using this composition for formation of a passivation layer.

  Specific means for solving the above problems are as follows.

<1> A composition for forming a passivation layer comprising a compound represented by the following general formula (I) and at least one selected from the group consisting of a fatty acid amide, a polyalkylene glycol compound and an organic filler.

M (OR ¹ ) _m (I)

In the formula, M includes at least one metal element selected from the group consisting of Nb, Ta, V, Y, and Hf. R ¹ each independently represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms. m represents an integer of 1 to 5.

<2> The composition for forming a passivation layer according to <1>, further comprising a compound represented by the following general formula (II).

Wherein, R ² each independently represent an alkyl group having 1 to 8 carbon atoms. n represents an integer of 0 to 3. X ² and X ³ each independently represent an oxygen atom or a methylene group. R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

<3> The passivation according to <1> or <2>, including the polyalkylene glycol compound, wherein the polyalkylene glycol compound includes at least one selected from compounds represented by the following general formula (III): Layer forming composition.

In formula (III), R ⁶ and R ⁷ each independently represent a hydrogen atom or an alkyl group, and R ⁸ represents an alkylene group. n is an integer of 3 or more. A plurality of R ⁸ may be the same or different.

<4> Including the fatty acid amide, wherein the fatty acid amide is represented by a compound represented by the following general formula (1), a compound represented by (2), a compound represented by (3), and (4) The composition for forming a passivation layer according to any one of <1> to <3>, comprising at least one selected from the group consisting of:

R ⁹ CONH ₂ (1)
R ⁹ CONH-R ¹⁰ -NHCOR ⁹ (2)
R ⁹ NHCO-R ¹⁰ -CONHR ⁹ (3)
R ⁹ CONH—R ¹⁰ —N (R ¹¹ ) ₂ ... (4)

In the general formulas (1), (2), (3) and (4), R ⁹ and R ¹¹ each independently represent an alkyl group having 1 to 30 carbon atoms or an alkenyl group having 2 to 30 carbon atoms, and R ¹⁰ represents an alkylene group having 1 to ¹⁰ carbon atoms. A plurality of R ¹¹ may be the same or different.

<5> The organic filler according to any one of <1> to <4>, including the organic filler, wherein the organic filler includes at least one selected from the group consisting of an acrylic resin, a cellulose resin, and a polystyrene resin. A composition for forming a passivation layer.

<6> a semiconductor substrate;
A passivation layer, which is a heat treatment product of the composition for forming a passivation layer according to any one of <1> to <5>, provided on the entire surface or a part of the semiconductor substrate;
A semiconductor substrate with a passivation layer.

<7> Forming a composition layer by applying the passivation layer forming composition according to any one of <1> to <5> to the entire surface or part of the semiconductor substrate;
Heat-treating the composition layer to form a passivation layer;
The manufacturing method of the semiconductor substrate with a passivation layer which has this.

<8> a semiconductor substrate in which a p-type layer and an n-type layer are pn-junction;
A passivation layer, which is a heat treatment product of the composition for forming a passivation layer according to any one of <1> to <5>, provided on the entire surface or a part of the semiconductor substrate;
An electrode disposed on one or more layers selected from the group consisting of the p-type layer and the n-type layer;
A solar cell element having

<9> A semiconductor substrate having a pn junction formed by joining a p-type layer and an n-type layer, and having an electrode on one or more layers selected from the group consisting of the p-type layer and the n-type layer. Forming a composition layer by applying the passivation layer forming composition according to any one of <1> to <5> on one or both of the surfaces having the electrodes;
Heat-treating the composition layer to form a passivation layer;
The manufacturing method of the solar cell element which has this.

<10> The solar cell element according to <8>,
A wiring material provided on the electrode of the solar cell element;
A solar cell having:

  ADVANTAGE OF THE INVENTION According to this invention, the passivation layer of a desired shape can be formed with a simple method, and the composition for formation of the passivation layer which is excellent in storage stability and excellent in coating-film uniformity can be provided. Further, according to the present invention, a semiconductor substrate with a passivation layer obtained using a composition for forming a passivation layer and having a passivation layer having an excellent passivation effect, a method for manufacturing a semiconductor substrate with a passivation layer, and excellent conversion efficiency are provided. A solar cell element, a method for manufacturing a solar cell element, and a solar cell can be provided.

It is sectional drawing which shows typically an example of the manufacturing method of the solar cell element which has a passivation layer concerning this embodiment. It is sectional drawing which shows typically another example of the manufacturing method of the solar cell element which has a passivation layer concerning this embodiment. It is sectional drawing which shows typically the back electrode type solar cell element which has a passivation layer concerning this embodiment. It is sectional drawing which showed the structure of the double-sided electrode type solar cell element. It is sectional drawing which shows the 1st structural example of the solar cell element which concerns on reference embodiment. It is sectional drawing which shows the 2nd structural example of the solar cell element which concerns on reference embodiment. It is sectional drawing which shows the 3rd structural example of the solar cell element which concerns on reference embodiment. It is sectional drawing which shows the 4th structural example of the solar cell element which concerns on reference embodiment. It is sectional drawing which shows another structural example of the solar cell element which concerns on reference embodiment.

  In this specification, the term “process” is not limited to an independent process, and is included in this term if the purpose of the process is achieved even when it cannot be clearly distinguished from other processes. In the present specification, a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. Further, in the present specification, the content of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition. Means. In addition, in the present specification, the term “layer” includes a configuration of a shape formed in part in addition to a configuration of a shape formed on the entire surface when observed as a plan view.

<Composition for forming a passivation layer>
The composition for forming a passivation layer of the present invention is a group consisting of a compound represented by the following general formula (I) (hereinafter also referred to as “compound of formula (I)”), a fatty acid amide, a polyalkylene glycol compound and an organic filler. And at least one selected from the following (hereinafter also referred to as “specific compound”). The composition for forming a passivation layer may further contain other components as necessary.

M (OR ¹ ) _m (I)

In the formula, M includes at least one metal element selected from the group consisting of Nb, Ta, V, Y, and Hf. R ¹ each independently represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms. m represents an integer of 1 to 5. When m is 2 or more, a plurality of groups represented by R ¹ may be the same or different.

A passivation layer having an excellent passivation effect can be formed into a desired shape by applying a composition for forming a passivation layer containing the above components to a semiconductor substrate and heat-treating (baking) the composition. In addition, the composition for forming a passivation layer contains the compound of formula (I), so that the occurrence of problems such as gelation is suppressed and the storage stability with time is excellent. Furthermore, the composition for forming a passivation layer is excellent in coating film uniformity by including a specific compound.
Moreover, the method using the composition for forming a passivation layer of the present invention is a simple and highly productive method that does not require a vapor deposition apparatus or the like. Further, the passivation layer can be formed in a desired shape without requiring a complicated process such as mask processing.

  In this specification, the passivation effect of a semiconductor substrate refers to an effective lifetime of minority carriers in a semiconductor substrate provided with a passivation layer by using a device such as Nippon Semilab Co., Ltd., WT-2000PVN, Sinton Instruments, WCT-120, etc. It can be evaluated by using the reflection microwave conductive attenuation method.

Here, the effective lifetime τ is expressed by the following equation (A) by the bulk lifetime τ _b inside the semiconductor substrate and the surface lifetime τ _s of the semiconductor substrate surface. When the surface state density on the surface of the semiconductor substrate is small, τ _s becomes long, resulting in a long effective lifetime τ. Further, even if defects such as dangling bonds in the semiconductor substrate are reduced, the bulk lifetime τ _b is increased and the effective lifetime τ is increased. That is, by measuring the effective lifetime τ, the interface characteristics between the passivation layer and the semiconductor substrate and the internal characteristics of the semiconductor substrate such as dangling bonds can be evaluated.

1 / τ = 1 / τ _b + 1 / τ _s (A)

  In addition, it shows that the recombination rate of a minority carrier is so slow that effective lifetime (tau) is long. Moreover, conversion efficiency improves by comprising a solar cell element using the semiconductor substrate with a long effective lifetime.

Moreover, the storage stability of the composition for forming a passivation layer can be evaluated by a change in viscosity over time. Specifically, the composition for forming a passivation layer immediately after preparation (within 12 hours) has a shear viscosity (η ⁰ ) at 25 ° C. and a shear rate of 1.0 s ⁻¹ and a passivation after storage at 25 ° C. for 30 days. Evaluation can be made by comparing the shear viscosity (η ³⁰ ) at 25 ° C. and a shear rate of 1.0 s ⁻¹ of the composition for layer formation, for example, by evaluating the rate of change in viscosity (%) over time. Can do. The rate of change in viscosity (%) over time is obtained by dividing the absolute value of the difference in shear viscosity immediately after preparation and 30 days later by the shear viscosity immediately after preparation, and is specifically calculated by the following equation. The viscosity change rate of the composition for forming a passivation layer is preferably 30% or less, more preferably 20% or less, and still more preferably 10% or less.
Viscosity change rate (%) = | η ³⁰ −η ⁰ | / η ⁰ × 100 (formula)

  Furthermore, the coating film uniformity of the composition for forming a passivation layer is determined by whether or not the composition for forming a passivation layer is present in the entire application portion on the semiconductor substrate when the composition for forming a passivation layer is applied to the semiconductor substrate. It is evaluated by what.

(Compound represented by formula (I))
The composition for forming a passivation layer contains at least one compound represented by the general formula (I). The compound of formula (I) is a compound called a metal alkoxide. The compound of formula (I) becomes a metal oxide of M in formula (I) by heat treatment (firing). When the composition for forming a passivation layer contains the compound of formula (I), a passivation layer having an excellent passivation effect can be formed. The reason for this can be considered as follows.

  The oxide formed by heat-treating (firing) the passivation layer-forming composition containing the compound of formula (I) is likely to be in an amorphous state, and defects such as metal atoms are generated and fixed near the interface with the semiconductor substrate. It is thought that it can have a charge. This negative fixed charge generates an electric field in the vicinity of the interface of the semiconductor substrate, so that the concentration of minority carriers can be reduced. As a result, the carrier recombination rate at the interface is suppressed, so that an excellent passivation effect is obtained. It is thought that it is played.

The fixed charge of the passivation layer can be evaluated by the CV method (Capacitance Voltage measurement). However, the surface state density of the passivation layer formed from the composition for forming a passivation layer of the present invention may be larger than that of a metal oxide layer formed by an ALD method or a CVD method. However passivation layer forming a passivation layer formed from the composition of the present invention, the concentration of electric field effect is increased minority carrier surface lifetime tau _s becomes longer decreases. Therefore, the surface state density is not a relative problem.

  In the general formula (I), M contains at least one metal element selected from the group consisting of Nb, Ta, V, Y and Hf. Among these, from the viewpoint of fixed charge and passivation effect, M preferably contains at least one metal element selected from the group consisting of Nb, Ta and Y, and more preferably contains Nb. From the viewpoint of making the fixed charge density of the passivation layer negative, M preferably contains at least one metal element selected from the group consisting of Nb, Ta, V, and Hf, and Nb, Ta, VO And at least one selected from the group consisting of Hf.

In the general formula (I), each R ¹ independently represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms, and when a plurality of R ¹ are present, each R ¹ is the same or different. May be. R ¹ is preferably an alkyl group having 1 to 8 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms.
The alkyl group represented by R ¹ may be linear or branched. Specific examples of the alkyl group represented by R ¹ include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, t-butyl group, hexyl group, octyl group, 2- An ethylhexyl group etc. can be mentioned.
Specific examples of the aryl group represented by R ¹ include a phenyl group.
The alkyl group and aryl group represented by R ¹ may have a substituent. Examples of the substituent for the alkyl group include a halogen atom, an amino group, a hydroxyl group, a carboxyl group, a sulfone group, and a nitro group. Examples of the substituent for the aryl group include a halogen atom, a methyl group, an ethyl group, an isopropyl group, an amino group, a hydroxyl group, a carboxyl group, a sulfone group, and a nitro group.
Among these, R ¹ is preferably an unsubstituted alkyl group having 1 to 8 carbon atoms, and more preferably an unsubstituted alkyl group having 1 to 4 carbon atoms, from the viewpoint of storage stability and a passivation effect.

  In general formula (I), m represents an integer of 1 to 5. From the viewpoint of storage stability, m is preferably 5 when M is Nb, m is preferably 5 when M is Ta, and M is VO. M is preferably 3, m is preferably 3 when M is Y, and m is preferably 4 when M is Hf.

The compound represented by the general formula (I) is composed of a compound in which m is 1 to 5 and R ¹ is independently an alkyl group having 1 to 4 carbon atoms from the viewpoint of storage stability and a passivation effect. It is preferably at least one selected from the group, m is 1 to 5, and R ¹ is at least one selected from the group consisting of compounds having an unsubstituted alkyl group having 1 to 4 carbon atoms. Is more preferable.

  Compounds represented by the general formula (I) are niobium methoxide, niobium ethoxide, niobium isopropoxide, niobium n-propoxide, niobium n-butoxide, niobium t-butoxide, niobium isobutoxide, tantalum methoxide, tantalum. Ethoxide, tantalum isopropoxide, tantalum n-propoxide, tantalum n-butoxide, tantalum t-butoxide, tantalum isobutoxide, yttrium methoxide, yttrium ethoxide, yttrium isopropoxide, yttrium n-propoxide, yttrium n- Butoxide, yttrium t-butoxide, yttrium isobutoxide, vanadium methoxide oxide, vanadium ethoxide oxide, vanadium isopropoxide oxide, vanadium n-propoxide oxide , Vanadium n-butoxide oxide, vanadium t-butoxide oxide, vanadium isobutoxide oxide, hafnium methoxide, hafnium ethoxide, hafnium isopropoxide, hafnium n-propoxide, hafnium n-butoxide, hafnium t-butoxide, hafnium isobutoxide Niobium ethoxide, niobium n-butoxide, tantalum ethoxide, tantalum n-butoxide, vanadium ethoxide oxide, yttrium ethoxide, and hafnium ethoxide are preferable. From the viewpoint of obtaining a negative fixed charge density, niobium ethoxide, niobium n-propoxide, niobium n-butoxide, tantalum ethoxide, tantalum n-propoxide, tantalum n-butoxide, vanadium ethoxide oxide, vanadium n-propoxy Preference is given to oxides, vanadium n-butoxide oxide, hafnium ethoxide, hafnium n-propoxide and hafnium n-butoxide.

  Moreover, the compound represented by general formula (I) may use what was prepared, or may use a commercial item. Commercially available products include, for example, pentamethoxyniobium, pentaethoxyniobium, penta-i-propoxyniobium, penta-n-propoxyniobium, penta-i-butoxyniobium, penta-n-butoxyniobium from High Purity Chemical Laboratory, Inc. , Penta-sec-butoxy niobium, pentamethoxy tantalum, pentaethoxy tantalum, penta-i-propoxy tantalum, penta-n-propoxy tantalum, penta-i-butoxy tantalum, penta-n-butoxy tantalum, penta-sec-butoxy tantalum , Penta-t-butoxytantalum, vanadium (V) trimethoxide oxide, vanadium (V) triethoxy oxide, vanadium (V) tri-i-propoxide oxide, vanadium (V) tri-n-propoxide oxide, vanadium (V Tri-i-butoxide oxide, vanadium (V) tri-n-butoxide oxide, vanadium (V) tri-sec-butoxide oxide, vanadium (V) tri-t-butoxide oxide, tri-i-propoxy yttrium, tri-n -Butoxy yttrium, tetramethoxy hafnium, tetraethoxy hafnium, tetra-i-propoxy hafnium, tetra-t-butoxy hafnium, pentaethoxyniobium, pentaethoxy tantalum, pentaboxy tantalum, yttrium-n-butoxide from Hokuko Chemical Co., Ltd. Hafnium-tert-butoxide, vanadium oxytriethoxide, vanadium oxytrinormal propoxide, vanadium oxytrinormal butoxide, vanadium oxy from Nichia Corporation Riisobutokishido, it can be mentioned vanadium oxy-tri secondary butoxide and the like.

  In the preparation of the compound represented by the general formula (I), a halide of a specific metal (M) and an alcohol are reacted in the presence of an inert organic solvent, and ammonia or an amine compound is used to further extract the halogen. Known methods such as a method of adding (JP-A 63-227593 and JP-A 3-291247) can be used.

  The compound represented by the general formula (I) may be used as a compound in which a chelate structure is formed by mixing with a compound having a specific structure having two carbonyl groups. In the compound having a chelate structure, at least a part of the alkoxide group of the compound of formula (I) is substituted with a compound having a specific structure to form a chelate structure. At this time, if necessary, a liquid medium may be present, or heat treatment, addition of a catalyst, and the like may be performed. By substituting at least part of the alkoxide structure with the chelate structure, the stability of the compound of formula (I) to hydrolysis and polymerization reaction is improved, and the storage stability of the composition for forming a passivation layer containing the compound is further improved. To do.

  The compound having a specific structure having two carbonyl groups is preferably at least one selected from the group consisting of a β-diketone compound, a β-ketoester compound and a malonic acid diester from the viewpoint of storage stability.

  Specific examples of the β-diketone compound include acetylacetone, 3-methyl-2,4-pentanedione, 2,3-pentanedione, 3-ethyl-2,4-pentanedione, and 3-butyl-2,4-pentane. Examples include dione, 2,2,6,6-tetramethyl-3,5-heptanedione, 2,6-dimethyl-3,5-heptanedione, 6-methyl-2,4-heptanedione, and the like.

  Specific examples of β-ketoester compounds include methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, isopropyl acetoacetate, isobutyl acetoacetate, butyl acetoacetate, t-butyl acetoacetate, pentyl acetoacetate, isopentyl acetoacetate, acetoacetic acid Hexyl, n-octyl acetoacetate, heptyl acetoacetate, 3-pentyl acetoacetate, ethyl 2-acetylheptanoate, ethyl 2-methylacetoacetate, ethyl 2-butylacetoacetate, ethyl hexylacetoacetate, 4,4-dimethyl-3- Ethyl oxovalerate, ethyl 4-methyl-3-oxovalerate, ethyl 2-ethylacetoacetate, methyl 4-methyl-3-oxovalerate, ethyl 3-oxohexanoate, ethyl 3-oxovalerate, 3-oxo Methyl valerate, 3-oxohexanoic acid Le, ethyl 3-oxo heptanoic acid, 3-oxo heptanoic acid methyl, can be mentioned 4,4-dimethyl-3-oxo-valerate, such as methyl.

  Specific examples of the malonic acid diester include dimethyl malonate, diethyl malonate, dipropyl malonate, diisopropyl malonate, dibutyl malonate, di-t-butyl malonate, dihexyl malonate, t-butylethyl malonate, methyl malonate Examples include diethyl, diethyl ethylmalonate, diethyl isopropylmalonate, diethyl butylmalonate, diethyl sec-butylmalonate, diethyl isobutylmalonate, diethyl 1-methylbutylmalonate, and the like.

When the compound of formula (I) has a chelate structure, the number of chelate structures is not particularly limited as long as it is 1 to 5. The number of carbonyl groups contributing to the chelate structure is not particularly limited, but when M is Nb, the number of carbonyl groups contributing to the chelate structure is preferably 1 to 5, and when M is Ta, the chelate structure It is preferable that the number of carbonyl groups contributing to 1 to 5 is preferable. When M is VO, the number of carbonyl groups contributing to the chelate structure is preferably 1 to 3, and when M is Y, the chelate structure is preferable. It is preferable that the number of carbonyl groups contributing to 1 is 1 to 3, and when M is Hf, the number of carbonyl groups contributing to the chelate structure is preferably 1 to 4.

  The number of chelate structures can be controlled, for example, by appropriately adjusting the ratio of mixing the compound of formula (I) with a compound capable of forming a chelate with a metal element. Moreover, you may select suitably the compound which has a desired structure from a commercially available metal chelate compound.

  The presence of a chelate structure in the compound of formula (I) can be confirmed by a commonly used analytical method. For example, it can be confirmed using an infrared spectrum, a nuclear magnetic resonance spectrum or a melting point.

  The state of the compound of formula (I) may be liquid or solid. From the viewpoint of the storage stability of the composition for forming a passivation layer and the miscibility in the case where a compound represented by the general formula (II) described later is used in combination, the compound represented by the general formula (I) is a normal temperature (25 C.) and is preferably liquid. When the compound of formula (I) is a solid, it is a compound having good solubility or dispersibility in a solvent from the viewpoint of the passivation effect of the formed passivation layer, the storage stability of the composition for forming a passivation layer, and the like. It is preferable that it is a compound that is stable when it is used as a solution or dispersion.

  The content of the compound of formula (I) contained in the composition for forming a passivation layer can be appropriately selected as necessary. The content of the compound of formula (I) can be set to 1% by mass to 80% by mass in the composition for forming a passivation layer from the viewpoint of storage stability and a passivation effect, and is 3% by mass to 70% by mass. It is preferably 5% by mass to 60% by mass, more preferably 10% by mass to 50% by mass.

(Compound represented by formula (II))
The composition for forming a passivation layer of the present invention preferably further contains at least one compound represented by the following general formula (II) (hereinafter sometimes referred to as “specific organoaluminum compound”).

Wherein, R ² each independently represent an alkyl group having 1 to 8 carbon atoms. n represents an integer of 0 to 3. X ² and X ³ each independently represent an oxygen atom or a methylene group. R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

The specific organoaluminum compound includes compounds called aluminum alkoxide, aluminum chelate and the like, and preferably has an aluminum chelate structure in addition to the aluminum alkoxide structure. Further, Nippon Seramikkusu Kyokai Gakuj u tsu Ronbunshi , vol.97, as described in pp369-399 (1989), the organoaluminum compound is an aluminum oxide by heat treatment _(sintering) (Al 2 _O 3). At this time, since the formed aluminum oxide tends to be in an amorphous state, a larger negative fixed charge can be obtained. As a result, it is considered that a passivation layer having an excellent passivation effect can be formed.

  In addition to the above, by combining the compound represented by the general formula (I) and the compound represented by the general formula (II), it is considered that the passivation effect is further enhanced by the respective effects in the passivation layer. Further, the metal (M) represented by the general formula (I) is heat-treated (fired) in a state where the compound represented by the general formula (I) and the compound represented by the general formula (II) coexist. As the composite metal alkoxide of aluminum and aluminum (Al), the physical properties such as reactivity and vapor pressure are improved, the denseness of the passivation layer as a heat-treated product (baked product) is improved, and as a result, the passivation effect becomes higher. Conceivable.

In general formula (II), R ² each independently represents an alkyl group having 1 to 8 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms. The alkyl group represented by R ² may be linear or branched. Specific examples of the alkyl group represented by R ² include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, t-butyl group, hexyl group, octyl group, 2- An ethylhexyl group etc. can be mentioned. Among them, the alkyl group represented by R ² is preferably an unsubstituted alkyl group having 1 to 8 carbon atoms from the viewpoint of storage stability and a passivation effect, and is an unsubstituted alkyl group having 1 to 4 carbon atoms. More preferably.

In general formula (II), n represents the integer of 0-3. From the viewpoint of storage stability, n is preferably an integer of 1 to 3, and more preferably 1 or 3. X ² and X ³ each independently represent an oxygen atom or a methylene group. From the viewpoint of storage stability, at least one of X ² and X ³ is preferably an oxygen atom.

R ³ , R ⁴ and R ⁵ in the general formula (II) each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. The alkyl group represented by R ³ , R ⁴ and R ⁵ may be linear or branched. The alkyl group represented by R ³ , R ⁴ and R ⁵ may have a substituent or may be unsubstituted, and is preferably unsubstituted. The alkyl group represented by R ³ , R ⁴ and R ⁵ is an alkyl group having 1 to 8 carbon atoms, and preferably an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group represented by R ³ , R ⁴ and R ⁵ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, and a hexyl group. Octyl group, ethylhexyl group and the like.

Among these, from the viewpoint of storage stability and a passivation effect, R ³ and R ⁴ in the general formula (II) are preferably each independently a hydrogen atom or an unsubstituted alkyl group having 1 to 8 carbon atoms. Or it is more preferable that it is a C1-C4 unsubstituted alkyl group.
R ⁵ in the general formula (II) is preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 8 carbon atoms from the viewpoint of storage stability and a passivation effect, and is a hydrogen atom or 1 to 4 carbon atoms. It is more preferably an unsubstituted alkyl group.

The compound represented by the general formula (II) is a compound in which n is 1 to 3 and R ⁵ is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms from the viewpoint of storage stability. Preferably there is.

The compound represented by the general formula (II) is a compound in which n is 0 and R ² is independently an alkyl group having 1 to 4 carbon atoms, and n, from the viewpoint of storage stability and a passivation effect. Is 1 to 3, R ² is independently an alkyl group having 1 to 4 carbon atoms, at least one of X ² and X ³ is an oxygen atom, and R ³ and R ⁴ are each independently hydrogen. It is preferably an atom or an alkyl group having 1 to 4 carbon atoms, and R ⁵ is at least one selected from the group consisting of a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
More preferably, in the compound represented by the general formula (II), n is 0, R ² is each independently an unsubstituted alkyl group having 1 to 4 carbon atoms, and n is 1 to 3 R ² is each independently an unsubstituted alkyl group having 1 to 4 carbon atoms, at least one of X ² and X ³ is an oxygen atom, and R ³ or R ⁴ bonded to the oxygen atom is A group consisting of a compound having an alkyl group having 1 to 4 carbon atoms and when X ² or X ³ is a methylene group, R ³ or R ⁴ bonded to the methylene group is a hydrogen atom, and R ⁵ is a hydrogen atom; It is at least 1 sort chosen from more.

  Specific examples of the specific organoaluminum compound (aluminum trialkoxide) in which n is 0 in formula (II) include trimethoxyaluminum, triethoxyaluminum, triisopropoxyaluminum, trisec-butoxyaluminum, monosec-butoxy- Examples thereof include diisopropoxyaluminum, tri-t-butoxyaluminum, and tri-n-butoxyaluminum.

Specific examples of the specific organoaluminum compound in which n is 1 to 3 in the general formula (II) include aluminum ethylacetoacetate diisopropylate [(ethylacetoacetate) aluminum isopropoxide ] , tris (ethylacetoacetate ) . ) Aluminum and the like can be mentioned.

  Moreover, what was prepared may be used for the specific organoaluminum compound whose n is 1-3 in General formula (II), or a commercial item may be used. Examples of commercially available products include Kawaken Fine Chemical Co., Ltd. trade names, ALCH, ALCH-50F, ALCH-75, ALCH-TR, ALCH-TR-20, and the like.

  The specific organoaluminum compound in which n is 1 to 3 in the general formula (II) can be prepared by mixing the aluminum trialkoxide and the compound having the specific structure having the two carbonyl groups described above.

  When an aluminum trialkoxide and a compound having a specific structure having two carbonyl groups are mixed, at least a part of the alkoxide group of the aluminum trialkoxide is substituted with the compound having the specific structure to form an aluminum chelate structure. At this time, if necessary, a liquid medium may be present, or heat treatment, addition of a catalyst, and the like may be performed. By replacing at least a part of the aluminum alkoxide structure with the aluminum chelate structure, the stability of the specific organoaluminum compound with respect to hydrolysis and polymerization reaction is improved, and the storage stability of the composition for forming a passivation layer containing this is further improved. improves.

  Examples of the compound having a specific structure having two carbonyl groups include the above-mentioned β-diketone compound, β-ketoester compound, malonic acid diester, and the like. From the viewpoint of storage stability, β-diketone compound, β-ketoester compound and It is preferably at least one selected from the group consisting of malonic acid diesters.

  When the specific organoaluminum compound has an aluminum chelate structure, the number of aluminum chelate structures is not particularly limited as long as it is 1 to 3. Among these, 1 or 3 is preferable from the viewpoint of storage stability, and 1 is more preferable from the viewpoint of solubility. The number of aluminum chelate structures can be controlled, for example, by appropriately adjusting the ratio of mixing aluminum trialkoxide and a compound having a specific structure having two carbonyl groups. Moreover, you may select suitably the compound which has a desired structure from a commercially available aluminum chelate compound.

  Among the compounds represented by the general formula (II), from the viewpoint of the passivation effect and the compatibility with the solvent contained as necessary, specifically, it consists of aluminum ethyl acetoacetate diisopropylate and triisopropoxyaluminum. It is preferable to use at least one selected from the group, and it is more preferable to use aluminum ethyl acetoacetate diisopropylate.

  The presence of the aluminum chelate structure in the specific organoaluminum compound can be confirmed by a commonly used analytical method, and can be confirmed using, for example, an infrared spectrum, a nuclear magnetic resonance spectrum, or a melting point.

  The specific organoaluminum compound may be liquid or solid and is not particularly limited. From the viewpoint of the passivation effect and storage stability, a specific organoaluminum compound having favorable stability at room temperature (25 ° C.) and good solubility or dispersibility is preferable, and the specific organoaluminum stable when used as a solution or dispersion A compound is preferred. By using such a specific organoaluminum compound, the homogeneity of the formed passivation layer is further improved, and a desired passivation effect tends to be stably obtained.

When the composition for forming a passivation layer contains a specific organoaluminum compound, the content of the specific organoaluminum compound is not particularly limited. Especially, it is preferable that the content rate of a specific organoaluminum compound when the total content rate of a compound of a formula (I) and a specific organoaluminum compound is 100 mass% is 0.5 to 80 mass%. The content is more preferably no less than 75% by mass and even more preferably no less than 2% by mass and no greater than 70% by mass, and particularly preferably no less than 3% by mass and no greater than 70% by mass.
By setting the content of the specific organoaluminum compound to 0.5% by mass or more, the storage stability of the composition for forming a passivation layer tends to be improved. Moreover, it exists in the tendency for the passivation effect to improve because the content rate of a specific organoaluminum compound shall be 80 mass% or less.

  When the composition for forming a passivation layer contains a specific organoaluminum compound, the content of the specific organoaluminum compound in the composition for forming a passivation layer can be appropriately selected as necessary. For example, from the viewpoint of storage stability and a passivation effect, the content of the specific organoaluminum compound can be 1% by mass to 70% by mass in the composition for forming a passivation layer, and 3% by mass to 60% by mass. It is preferably 5% by mass to 50% by mass, more preferably 10% by mass to 30% by mass.

(Specific compounds)
The composition for forming a passivation layer of the present invention contains at least one (specific compound) selected from the group consisting of a fatty acid amide, a polyalkylene glycol compound and an organic filler. The composition for forming a passivation layer of the present invention containing a specific compound has a reduced viscosity when applied to a semiconductor substrate, and an increased viscosity after being applied. Therefore, the passivation layer forming composition of the present invention can form a passivation layer having a desired shape by a simple method.

  Moreover, there exists a tendency for the composition layer which is a coating film of the composition for passivation layer formation to become more uniform by containing a specific compound. This is thought to be because entrainment of bubbles is suppressed by lowering the viscosity of the composition for forming a passivation layer when applying the composition for forming a passivation layer to a semiconductor substrate.

  The content of the specific compound contained in the composition for forming a passivation layer can be appropriately selected as necessary. For example, from the viewpoints of printability and passivation effect, the content of the specific compound can be 0.01% by mass to 70% by mass in the composition for forming a passivation layer, and 0.01% by mass to 60% by mass. It is preferable that it is 0.01 mass%-50 mass%.

[Polyalkylene glycol compound]
The polyalkylene glycol compound in the present invention may be liquid or solid and is not particularly limited. From the viewpoints of the passivation effect and printability, polyalkylene glycol compounds having good stability at room temperature (25 ° C.) and good solubility or dispersibility are preferred. By using such a polyalkylene glycol compound, the uniformity of the formed passivation layer is further improved, and a desired passivation effect tends to be stably obtained.

  The polyalkylene glycol compound preferably contains at least one selected from compounds represented by the following general formula (III).

In formula (III), R ⁶ and R ⁷ each independently represent a hydrogen atom or an alkyl group, and R ⁸ represents an alkylene group. n is an arbitrary integer of 3 or more. A plurality of R ⁸ may be the same or different.

  In general formula (III), n represents an integer of 3 or more. From the viewpoint of printability, n is preferably 5 to 23000, more preferably 10 to 11000, and still more preferably 20 to 2300. When n is 3 or more, it tends to be easily adjusted to a viscosity suitable for printing while suppressing the content of the compound represented by formula (III) in the composition for forming a passivation layer. Moreover, there exists a tendency to suppress that the viscosity of the composition for passivation layer formation becomes high too much that n is 23000 or less.

R ⁶ and R ⁷ in the general formula (III) each independently represent a hydrogen atom or an alkyl group. The alkyl group represented by R ⁶ and R ⁷ preferably has 1 to 10 carbon atoms, more preferably 1 to 5 and still more preferably 1 or 2.
Specifically, R ⁶ and R ⁷ are each independently a hydrogen atom, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, t-butyl group, hexyl group, octyl group And preferably an ethylhexyl group, more preferably a hydrogen atom, a methyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group or a t-butyl group, and a hydrogen atom, a methyl group or More preferably, it is an ethyl group.

R ⁸ in the general formula (III) represents an alkylene group. The alkylene group represented by R ⁸ preferably has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and still more preferably 1 to 3 carbon atoms.
Specifically, R ⁸ is preferably an ethylene group, a propylene group, a hexylene group, an octylene group, a dodecylene group or a hexadecylene group, more preferably an ethylene group, a propylene group, a hexylene group or an octylene group, More preferably, it is a group or a propylene group.

  Specific examples of the compound represented by the general formula (III) include polyethylene glycol, polypropylene glycol, polyethylene glycol monomethyl ether, poly (ethylene glycol-propylene glycol) copolymer, and the like. Among these, polyethylene glycol is preferable. By using polyethylene glycol, the printability of the composition for forming a passivation layer tends to be improved, and polyethylene glycol is easily available.

As a compound represented by general formula (III), 1 type may be used independently, or the compound represented by 2 or more types of general formula (III) from which a structure differs may be used together. Moreover, you may use the compound represented by general formula (III) by copolymerizing with another specific compound.
When two or more kinds of compounds represented by the general formula (III) having different structures are used in combination, the combination includes a combination of polyethylene glycol and polypropylene glycol, a combination of polyethylene glycol and polyethylene glycol monomethyl ether, and the like. .

  The compound represented by the general formula (III) may be liquid or solid. From the viewpoint of the passivation effect of the formed passivation layer and the printability of the composition for forming a passivation layer, when the compound represented by the general formula (III) is a solid, it dissolves in a solvent at room temperature (25 ° C.). It is preferable that the compound has good properties or dispersibility, and it is preferable that the compound is stable when it is used as a solution or dispersion. In the case of such a compound, the homogeneity of the formed passivation layer is further improved, and a desired passivation effect can be stably obtained.

When the compound represented by the general formula (III) has a glass transition temperature, the glass transition temperature is not particularly limited, and is preferably in the range of −100 ° C. to 100 ° C., and in the range of −50 ° C. to 25 ° C. It is more preferable that
The glass transition temperature of the compound in the present invention represented by the general formula (III), to examine was measured using shows differences thermal analyzer, differential scanning calorimetry (DSC, Differential scanning calorimetry) the mutation point of the curve Can be measured.

When the compound represented by the general formula (III) has a melting point, the melting point is not particularly limited and is preferably in the range of 20 ° C to 200 ° C, more preferably in the range of 40 ° C to 100 ° C. .
The melting point of the compound represented by the general formula (III) in the present invention was measured using a shows differences thermal analyzer can be measured by examining the melting peak.

The number average molecular weight of the compound represented by the general formula (III) is preferably 1,000 to 5,000,000, and more preferably 2,000 to 5,000,000. When the number average molecular weight is 1000 or more, the functionality as a thixotropic agent is sufficiently exhibited, and when it is 5,000,000 or less, the viscosity of the composition for forming a passivation layer can be prevented from becoming too high. Therefore, the printability becomes better. Moreover, there exists a tendency for printability to become further favorable that it is 2,000 or more.
The number average molecular weight can be measured using gel permeation chromatography (GPC method). In addition, the measurement conditions of the number average molecular weight by GPC method are as follows, for example.

Measuring device: Shodex GPC SYSTEM-11 (Showa Denko KK)
Eluent: CF3COONa 5 mmol / hexafluoroisopropyl alcohol (HFIP) (1 liter)
Column: Sample column HFIP-800P HFIP-80M × 2, Reference column HFIP-800R × 2 Column temperature: 40 ° C.
Flow rate: 1.0 ml / min Detector: Shodex RI STD: PMMA (Shodex STANDARD M-75)

[Fatty acid amide]
The fatty acid amide is at least selected from the group consisting of a compound represented by the following general formula (1), a compound represented by (2), a compound represented by (3), and a compound represented by (4) It is preferable that 1 type is included. In addition, fatty acid amide may be used individually by 1 type, or may use 2 or more types together.

R ⁹ CONH ₂ (1)
R ⁹ CONH-R ¹⁰ -NHCOR ⁹ (2)
R ⁹ NHCO-R ¹⁰ -CONHR ⁹ (3)
R ⁹ CONH—R ¹⁰ —N (R ¹¹ ) ₂ ... (4)

In the general formulas (1), (2), (3) and (4), R ⁹ and R ¹¹ each independently represent an alkyl group having 1 to 30 carbon atoms or an alkenyl group having 2 to 30 carbon atoms, and R ¹⁰ Represents an alkylene group having 1 to 10 carbon atoms. A plurality of R ¹¹ may be the same or different.

Formula (1), (2), (3) and (4), the alkyl groups each independently represented by ^{R 9} and ^{R 11,} 1 to 30 carbon atoms, in view of printability and passivation effect Therefore, it is preferable that it is C1-C25, and it is more preferable that it is C1-C20.
In the general formulas (1), (2), (3), and (4), the alkenyl groups represented by R ⁹ and R ¹¹ each independently have 2 to 30 carbon atoms, and have good printability and passivation effect. From a viewpoint, it is preferable that it is C2-C25, and it is more preferable that it is C2-C20.

The alkyl group and alkenyl group represented by R ⁹ and R ¹¹ may each independently be linear, branched or cyclic, and are preferably linear or branched.

The alkyl group and alkenyl group represented by R ⁹ and R ¹¹ may be unsubstituted or may have a substituent. Examples of such a substituent include a hydroxyl group, a chloro group, a bromo group, a fluoro group, an aldehyde group, a carbonyl group, a nitro group, an amine group, a sulfonic acid group, an alkoxy group, and an acyloxy group.

Specific examples of the alkyl group and alkenyl group represented by R ⁹ and R ¹¹ include a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, an isobutyl group, a decane group, a dodecane group, an octadecane group, and a hexadecenyl group. And henicosenyl group.

The alkyl group and alkenyl group represented by R ⁹ each independently preferably have 5 to 25 carbon atoms, more preferably 10 to 20 carbon atoms, and further preferably 15 to 18 carbon atoms. preferable.

The alkyl group represented by R ¹¹ is preferably independently of 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and still more preferably 1 to 3 carbon atoms. The alkenyl group represented by R ¹¹ preferably independently has 2 to 10 carbon atoms, more preferably 2 to 6 carbon atoms, and still more preferably 2 to 3 carbon atoms.

R ⁹ is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, still more preferably an alkyl group having 1 to 6 carbon atoms, Although it is a C1-C3 alkyl group, it is especially preferable.

In the general formulas (2), (3), and (4), the alkylene group represented by R ¹⁰ has 2 to 10 carbon atoms independently, and from the viewpoint of printability and passivation effect, 2 to 2 carbon atoms. 8 is preferable, C 2-6 is more preferable, and C 2-4 is still more preferable. The alkylene group represented by R ¹⁰ may be linear or branched. Specific examples of the alkylene group represented by R ⁸ include an ethylene group, a propylene group, a butylene group, and an octylene group.

  Specific examples of the fatty acid monoamide represented by the general formula (1) include lauric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, erucic acid amide and the like.

  Specific examples of the N-substituted fatty acid amide represented by the general formula (2) include N, N′-ethylenebislauric acid amide, N, N′-methylenebisstearic acid amide, N, N′-ethylenebis. Stearic acid amide, N, N′-ethylenebisoleic acid amide, N, N′-ethylenebisbehenic acid amide, N, N′-ethylenebis-12-hydroxystearic acid amide, N, N′-butylene bisstearic acid Examples include amide, N, N′-hexamethylene bisstearic acid amide, N, N′-hexamethylene bisoleic acid amide, N, N′-xylylene bisstearic acid amide, and the like.

  Specific examples of the N-substituted fatty acid amide represented by the general formula (3) include N, N′-dioleyl adipic acid amide, N, N′-distearyl adipic acid amide, N, N′-dioleyl. Examples include sebacic acid amide, N, N′-distearyl sebacic acid amide, N, N′-distearyl terephthalic acid amide, N, N′-distearyl isophthalic acid amide, and the like.

  Specific examples of the N-substituted fatty acid amidoamine represented by the general formula (4) include stearic acid dimethylaminopropylamide, stearic acid diethylaminoethylamide, lauric acid dimethylaminopropylamide, myristic acid dimethylaminopropylamide, palmitic acid. Dimethylaminopropylamide, stearic acid dimethylaminopropylamide, behenic acid dimethylaminopropylamide, oleic acid dimethylaminopropylamide, isostearic acid dimethylaminopropylamide, linoleic acid dimethylaminopropylamide, ricinoleic acid dimethylaminopropylamide, hydroxystearic acid Dimethylaminopropylamide, stearic acid N, N-dihydroxymethylaminopropylamide, lauric acid diethylamino ester Luamide, myristic acid diethylaminoethylamide, palmitic acid diethylaminoethylamide, stearic acid diethylaminoethylamide, behenic acid diethylaminoethylamide, oleic acid diethylaminoethylamide, linoleic acid diethylaminoethylamide, ricinoleic acid diethylaminoethylamide, isostearic acid diethylaminoethylamide, Hydroxy stearic acid diethylaminoethylamide, stearic acid N, N-dihydroxyethylaminoethylamide, lauric acid diethylaminopropylamide, myristic acid diethylaminopropylamide, palmitic acid diethylaminopropylamide, stearic acid diethylaminopropylamide, behenic acid diethylaminopropylamide, olein Diethylamino acid Ropiruamido, linoleic acid diethylaminopropylamide, ricinoleic acid diethylaminopropylamide, isostearic acid diethylaminopropylamide, hydroxystearic acid diethylaminopropylamide, stearic acid N, N-dihydroxyethyl-aminopropyl amide.

  Among these fatty acid amides, at least one selected from the group consisting of stearic acid amide, N, N′-methylenebisstearic acid amide and stearic acid dimethylaminopropylamide is used from the viewpoint of solubility in a dispersion medium. It is preferable.

  The fatty acid amide may be liquid or solid. From the viewpoint of the passivation effect and printability, when the fatty acid amide is a solid, it is preferably a compound that has good solubility or dispersibility at room temperature (25 ° C.) with respect to the solvent. Sometimes a stable compound is preferred. In the case of such a compound, the homogeneity of the formed passivation layer is further improved, and a desired passivation effect can be stably obtained.

  The fatty acid amide is desirably evaporated or decomposed at 30 to 400 ° C, more preferably evaporated or decomposed at 40 to 300 ° C, and further desirably evaporated or decomposed at 50 to 250 ° C or lower. It is preferable that the fatty acid amide evaporates or disperses at 400 ° C. or lower because it does not inhibit the formation of the passivation layer.

When using at least one selected from the group consisting of polyalkylene glycol compound and a fatty acid amide as the specific compound, suitable compounds, printability and solubility standpoint or these into the dispersion medium, polyethylene glycols, polypropylene glycols , Stearic acid amide, N, N′-methylenebisstearic acid amide and stearic acid dimethylaminopropylamide are preferably used, and at least one selected from polyethylene glycol and stearic acid amide is preferably used. It is more preferable.

[Organic filler]
The organic filler is preferably a particle or a fibrous material composed of an organic compound. Organic filler materials include urea formalin resin, phenol resin, polycarbonate resin, melamine resin, epoxy resin, unsaturated polyester resin, silicone resin, polyurethane resin, polyolefin resin, acrylic resin, fluorine resin, polystyrene resin, cellulose resin, formaldehyde Examples thereof include resins, coumarone indene resins, lignin resins, petroleum resins, amino resins, polyester resins, polyether sulfone resins, butadiene resins, and copolymers thereof. An organic filler is used individually by 1 type or in combination of 2 or more types.

  The material of the organic filler is preferably at least one selected from the group consisting of an acrylic resin, a cellulose resin, and a polystyrene resin, more preferably an acrylic resin, from the viewpoint of thermal decomposability.

  Monomers constituting the acrylic resin include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, and acrylic acid. n-butyl, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, sec-butyl acrylate, sec-butyl methacrylate, t-butyl acrylate, t-butyl methacrylate, pentyl acrylate, pentyl methacrylate, Hexyl acrylate, hexyl methacrylate, heptyl acrylate, heptyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, octyl acrylate, octyl methacrylate, nonyl acrylate, methacrylate Nonyl, decyl acrylate, decyl methacrylate, dodecyl acrylate, dodecyl methacrylate, tetradecyl acrylate, tetradecyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, eicosyl acrylate, eicosyl methacrylate , Docosyl acrylate, docosyl methacrylate, cyclopentyl acrylate, cyclopentyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, cycloheptyl acrylate, cycloheptyl methacrylate, benzyl acrylate, benzyl methacrylate, phenyl acrylate, phenyl methacrylate , Methoxyethyl acrylate, methoxyethyl methacrylate, dimethylaminoethyl acrylate, meta Dimethylaminoethyl acrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminopropyl acrylate, dimethylaminopropyl methacrylate, 2-chloroethyl acrylate, 2-chloroethyl methacrylate, 2-fluoroethyl acrylate, methacrylic acid 2 -Fluoroethyl, styrene, α-methylstyrene, cyclohexylmaleimide, dicyclopentanyl acrylate, dicyclopentanyl methacrylate, vinyl toluene, vinyl chloride, vinyl acetate, N-vinyl pyrrolidone, butadiene, isoprene, chloroprene, etc. It is done. These are used singly or in combination of two or more.

  The organic filler is solid in the liquid medium. From the viewpoint of the passivation effect and printability, the organic filler is preferably an organic filler that has good dispersibility at room temperature (25 ° C.) with respect to a liquid medium, and is preferably an organic filler that is stable when used as a dispersion. In the case of such an organic filler, the uniformity of the formed passivation layer is further improved, and a desired passivation effect can be stably obtained.

  The organic filler is preferably one that decomposes at 30 ° C to 400 ° C, more preferably the decomposition temperature is 40 ° C to 300 ° C, and still more preferably 50 ° C to 250 ° C. When the organic filler is decomposed at 400 ° C. or lower, a composition layer is formed from the composition for forming a passivation layer, and the composition layer is subjected to a heat treatment (firing) to form a passivation layer. Is preferable.

  The decomposition temperature can be measured by a thermogravimetric analyzer (Shimadzu Corporation, DTG-60H). Moreover, the decomposition temperature here means the temperature at which the substance begins to lose weight due to the influence of heat.

  When the organic filler has a particle shape, the volume average particle diameter is preferably 10 μm or less, more preferably 1 μm or less, and further preferably 0.1 μm or less. When the volume average particle size is 10 μm or less, there is a tendency that a greater thixotropy can be obtained with a small amount of addition. In addition, when a screen printing method is used as a method for applying the composition for forming a passivation layer, clogging of the mesh of the printing mask can be suppressed.

  Here, the volume average particle diameter of the organic filler can be measured by a laser diffraction scattering particle size distribution measuring apparatus (for example, Beckman Coulter LS13320), and the value obtained by calculating the median diameter from the obtained particle size distribution is defined as the average particle diameter. be able to. Moreover, an average particle diameter can also be calculated | required by observing using SEM (scanning electron microscope).

  The content of the specific compound contained in the composition for forming a passivation layer can be appropriately selected as necessary. For example, from the viewpoint of printability and a passivation effect, the composition for forming a passivation layer can be 0.01% by mass to 70% by mass, preferably 0.01% by mass to 60% by mass, More preferably, the content is 0.01% by mass to 50% by mass.

(resin)
The composition for forming a passivation layer may further contain at least one resin. By including the resin, the shape stability of the composition layer formed by applying the composition for forming the passivation layer on the semiconductor substrate is further improved, and the passivation layer is formed in a desired region in the region where the composition layer is formed. It can be selectively formed by shape.

The type of resin is not particularly limited. Among these, when the composition for forming a passivation layer is applied on a semiconductor substrate, a resin capable of adjusting the viscosity within a range in which a good pattern can be formed is preferable. Specific examples of the resin include polyvinyl alcohol, polyacrylamide, polyacrylamide derivatives, polyvinyl amide, polyvinyl amide derivatives, polyvinyl pyrrolidone, polyethylene oxide, polyethylene oxide derivatives, polysulfonic acid, acrylamide alkyl sulfonic acid, cellulose, cellulose derivatives (carboxymethyl cellulose, Hydroxyethyl cellulose, cellulose ethers such as ethyl cellulose), gelatin, gelatin derivatives, starch, starch derivatives, sodium alginate, sodium alginate derivatives, xanthan, xanthan derivatives, guar gum, guar gum derivatives, scleroglucan, scleroglucan derivatives, tragacanth, tragacanth Derivatives, dextrin, dextrin derivatives, (meth) ac Examples thereof include phosphoric acid resins, (meth) acrylic acid ester resins (alkyl (meth) acrylate resins, dimethylaminoethyl (meth) acrylate resins, etc.), butadiene resins, styrene resins, siloxane resins, and copolymers thereof. . These resins can be used alone or in combination of two or more.
In the present specification, “(meth) acrylic acid” means at least one of “acrylic acid” and “methacrylic acid”, and “(meth) acrylate” means at least one of “acrylate” and “methacrylate”. means.

Among these resins, from the viewpoint of storage stability and pattern formation, it is preferable to use a neutral resin having no acidic or basic functional group, and even when the content is small, viscosity and From the viewpoint of adjusting thixotropy, it is more preferable to use a cellulose derivative such as ethyl cellulose.
Further, the molecular weight of these resins is not particularly limited, and it is preferable to adjust appropriately in view of the desired viscosity as the composition for forming a passivation layer. The weight average molecular weight of the resin is preferably 100 to 10,000,000, more preferably 1,000 to 5,000,000, from the viewpoints of storage stability and pattern formation. In addition, the weight average molecular weight of resin is calculated | required by converting using the analytical curve of a standard polystyrene from the molecular weight distribution measured using GPC (gel permeation chromatography). The molecular weight of the resin is measured under the same measurement conditions as those for the compound represented by the general formula (III).

  When the composition for forming a passivation layer contains a resin, the content of the resin in the composition for forming a passivation layer can be appropriately selected as necessary. For example, when the composition for forming a passivation layer contains a resin, the content of the resin in the composition for forming a passivation layer is preferably 0.1% by mass to 50% by mass. From the viewpoint of expressing thixotropy that facilitates pattern formation, the content is more preferably 0.2% by mass to 25% by mass, and preferably 0.5% by mass to 20% by mass. More preferably, it is particularly preferably 0.5% by mass to 15% by mass.

  When the composition for forming a passivation layer contains a resin, the compound of formula (I) in the composition for forming a passivation layer (when further containing a specific organoaluminum compound, the total amount of the compound of formula (I) and the specific organoaluminum compound) ) And the content ratio (mass ratio) of the resin can be appropriately selected as necessary. Among these, from the viewpoint of pattern formation and storage stability, the content ratio of the resin to the compound of the formula (I) (resin / the compound of the formula (I)), and further containing the specific organoaluminum compound, the compound of the formula (I) The content ratio of the resin to the total amount of the specific organoaluminum compound [resin / (formula (I) compound + specific organoaluminum compound)] is preferably 0.001 to 1000, and preferably 0.01 to 100. More preferably, it is still more preferably 0.1-1.

(Liquid medium)
The composition for forming a passivation layer may further contain a liquid medium (solvent or dispersion medium). When the composition for forming a passivation layer contains a liquid medium, the viscosity can be easily adjusted, the impartability is further improved, and a more uniform passivation layer tends to be formed. It does not restrict | limit especially as a liquid medium, It can select suitably as needed. Among them, a liquid medium capable of obtaining a uniform solution or dispersion by dissolving the compound of formula (I) and the specific organoaluminum compound used as necessary, a resin or the like is preferable, and includes at least one organic solvent. Is more preferable.
In addition, some compounds of formula (I) readily undergo hydrolysis, polymerization reaction and the like to solidify as they are, but the reaction is suppressed by dissolving or dispersing the compound of formula (I) in a liquid medium. Therefore, the storage stability tends to be improved.

  Specific examples of the liquid medium include acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl isopropyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone, methyl n-hexyl ketone, diethyl ketone, Ketone solvents such as dipropyl ketone, diisobutyl ketone, trimethylnonanone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone; diethyl ether, methyl ethyl ether, methyl-n-propyl ether, diisopropyl Ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, dimethyldioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol Rudi-n-propyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl n-propyl ether, diethylene glycol methyl n-butyl ether, diethylene glycol di-n-propyl ether, diethylene glycol di- n-butyl ether, diethylene glycol methyl-n-hexyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol methyl-n-butyl ether, triethylene glycol di-n-butyl ether, triethylene Glycolme Ru-n-hexyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol methyl ethyl ether, tetraethylene glycol methyl n-butyl ether, tetraethylene glycol di-n-butyl ether, tetraethylene glycol methyl n- Hexyl ether, tetraethylene glycol di-n-butyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n-propyl ether, propylene glycol dibutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol methyl Ethyl ether, dipropylene glycol Cyl-n-butyl ether, dipropylene glycol di-n-propyl ether, dipropylene glycol di-n-butyl ether, dipropylene glycol methyl-n-hexyl ether, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, tripropylene glycol methyl Ethyl ether, tripropylene glycol methyl-n-butyl ether, tripropylene glycol di-n-butyl ether, tripropylene glycol methyl-n-hexyl ether, tetrapropylene glycol dimethyl ether, tetrapropylene glycol diethyl ether, tetrapropylene glycol methyl ethyl ether, tetra Propylene glycol methyl-n-butyl ether, tetrapropylene glycol Ether solvents such as alkyl di-n-butyl ether, tetrapropylene glycol methyl-n-hexyl ether, tetrapropylene glycol di-n-butyl ether; methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate Sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, 2- (2-butoxyethoxy) ethyl acetate, benzyl acetate, Cyclohexyl acetate, methyl cyclohexyl acetate, nonyl acetate, methyl acetoacetate, ethyl acetoacetate, diethylene glycol methyl ether acetate, diethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate Dipropylene glycol ethyl ether, glycol diacetate, methoxytriethylene glycol acetate, isoamyl acetate, ethyl propionate, n-butyl propionate, isoamyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, lactic acid Ethyl, n-butyl lactate, n-amyl lactate, ethylene glycol methyl ether propionate, ethylene glycol ethyl ether propionate, ethylene glycol methyl ether acetate, ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether Ester solvents such as acetate, propylene glycol propyl ether acetate, γ-butyrolactone, γ-valerolactone; Ril, N-methylpyrrolidinone, N-ethylpyrrolidinone, N-propylpyrrolidinone, N-butylpyrrolidinone, N-hexylpyrrolidinone, N-cyclohexylpyrrolidinone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, etc. Aprotic polar solvents; hydrophobic organic solvents such as methylene chloride, chloroform, dichloroethane, benzene, toluene, xylene, hexane, octane, ethylbenzene, 2-ethylhexanoic acid, methyl isobutyl ketone, methyl ethyl ketone; methanol, ethanol, n-propanol , Isopropanol, n-butanol, isobutanol, sec-butanol, t-butanol, n-pentanol, isopentanol, 2-methylbutanol, sec-pentanol , T-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n- Nonyl alcohol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, cyclohexanol, methylcyclohexanol, benzyl alcohol, ethylene glycol, 1,2-propylene glycol, 1 , 3-butylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, isobornyl cyclohexanol and other alcohol solvents Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-n-hexyl ether, ethoxytriglycol, tetraethylene glycol mono- Glycol monoether solvents such as n-butyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether; terpinene, terpineol, myrcene, alloocimene, limonene, dipentene, pinene, carvone, Osmen, Terpene solvents such as Erandoren; and water. These liquid media are used alone or in combination of two or more.

  Among these, the liquid medium preferably contains at least one selected from the group consisting of a terpene solvent, an ester solvent, and an alcohol solvent, and is selected from the group consisting of a terpene solvent, from the viewpoint of impartability to a semiconductor substrate and pattern formation. More preferably, at least one kind is included.

  A liquid medium having a high viscosity and a low boiling point (high viscosity, low boiling point solvent) may be used. The composition for forming a passivation layer containing a high-viscosity low-boiling solvent has a viscosity that can sufficiently maintain the shape of the composition layer formed by applying it to a semiconductor substrate, and volatilizes during the subsequent heat treatment (firing) step. There is an advantage that the influence of the residual solvent can be suppressed. Specific examples of the high-viscosity low-boiling solvent include isobornylcyclohexanol.

  Isobornylcyclohexanol is commercially available as “Telsolve MTPH” (Nippon Terpene Chemical Co., Ltd., trade name). Isobornylcyclohexanol has a high boiling point of 308 ° C. to 318 ° C. When it is removed from the composition layer, it does not need to be degreased by heat treatment (firing) like a resin, but is vaporized by heating. Can be eliminated. For this reason, most of the solvent and isobornyl cyclohexanol contained in the composition for forming a passivation layer as necessary can be removed in the drying step after application on the semiconductor substrate.

  When the composition for forming a passivation layer contains a high-viscosity low-boiling solvent, the content of the high-viscosity low-boiling solvent is preferably 3% by mass to 95% by mass in the total mass of the composition for forming a passivation layer. More preferably, it is 5 mass%-90 mass%, and it is especially preferable that it is 7 mass%-80 mass%.

  When the composition for forming a passivation layer includes a liquid medium, the content of the liquid medium is determined in consideration of the imparting property, the pattern forming property, and the storage stability. For example, the content of the liquid medium is preferably 5% by mass to 98% by mass in the composition for forming a passivation layer from the viewpoint of the impartability of the composition and the pattern forming property, and 10% by mass to 95% by mass. It is more preferable that

(Other additives)
The composition for forming a passivation layer may contain an acidic compound or a basic compound. When the composition for forming a passivation layer contains an acidic compound or a basic compound, from the viewpoint of storage stability, the content of the acidic compound and the basic compound is 1% by mass or less in the composition for forming a passivation layer, respectively. It is preferable that the content is 0.1% by mass or less.

  Examples of acidic compounds include Bronsted acid and Lewis acid. Specific examples include inorganic acids such as hydrochloric acid and nitric acid, and organic acids such as acetic acid. Examples of basic compounds include Bronsted bases and Lewis bases. Specifically, examples of basic compounds include inorganic bases such as alkali metal hydroxides and alkaline earth metal hydroxides, and trialkyls. Examples thereof include organic bases such as amine and pyridine.

The composition for forming a passivation layer may contain at least one oxide selected from the group consisting of Nb, Ta, V, Y, and Hf (hereinafter referred to as “specific oxide”). Since the specific oxide is an oxide generated by heat-treating (sintering) the compound of formula (I), the passivation layer formed from the composition for forming a passivation layer containing the specific oxide has an excellent passivation effect. Is expected to be played.
The composition for forming a passivation layer may further contain aluminum oxide (Al ₂ O ₃ ). Aluminum oxide is an oxide produced by heat-treating (firing) a compound represented by the formula (II). Therefore, the composition for forming a passivation layer containing the compound of formula (I) and aluminum oxide is expected to exhibit an excellent passivation effect.

(Physical property value)
The viscosity of the composition for forming a passivation layer is not particularly limited, and can be appropriately selected depending on a method for applying the composition to a semiconductor substrate. For example, the viscosity of the composition for forming a passivation layer can be 0.01 Pa · s to 10000 Pa · s. Among these, from the viewpoint of pattern formability, the viscosity of the composition for forming a passivation layer is preferably 0.1 Pa · s to 1000 Pa · s. The viscosity is measured at 25 ° C. and a shear rate of 1.0 s ⁻¹ using a rotary shear viscometer.

Moreover, the shear viscosity of the composition for forming a passivation layer is not particularly limited, and it is preferable that the composition for forming a passivation layer has thixotropy. Among them from the viewpoints of pattern formability, thixotropic ratio calculated by dividing the shear viscosity eta ₁ at shear viscosity eta ₂ at a shear rate of ^{10s -1} at a shear rate of ^{_{1.0s -1 (η 1 / η 2}} ) is 1. It is preferable that it is 05-100, and it is more preferable that it is 1.1-50. The shear viscosity is measured at a temperature of 25 ° C. using a rotary shear viscometer equipped with a cone plate (diameter 50 mm, cone angle 1 °).

  The components contained in the composition for forming a passivation layer and the content of each component are determined by thermal analysis such as differential thermal-thermogravimetric simultaneous measurement (TG / DTA), nuclear magnetic resonance (NMR), infrared spectroscopy ( It can be confirmed by spectral analysis such as IR), chromatographic analysis such as high performance liquid chromatography (HPLC), gel permeation chromatography (GPC) and the like.

(Method for producing a composition for forming a passivation layer)
There is no restriction | limiting in particular in the manufacturing method of the composition for formation of a passivation layer. For example, the compound represented by the general formula (I), at least one selected from fatty acid amides, polyalkylene glycol compounds and organic fillers, and a liquid medium or the like contained as needed are usually mixed. It can manufacture by mixing with. Alternatively, at least one selected from a fatty acid amide, a polyalkylene glycol compound and an organic filler may be dissolved in a liquid medium and then mixed with the compound represented by the general formula (I). .

  Furthermore, the compound represented by the general formula (I) may be prepared by mixing a metal alkoxide contained in the compound of the formula (I) with a compound capable of forming a chelate with the metal. At that time, a liquid medium may be used as necessary, or heat treatment may be performed. A composition for forming a passivation layer is produced by mixing the compound of formula (I) thus prepared and a solution or dispersion containing at least one selected from fatty acid amides, polyalkylene glycol compounds and organic fillers. May be.

<Semiconductor substrate with passivation layer>
The semiconductor substrate with a passivation layer of the present invention includes a semiconductor substrate and a passivation layer that is a heat treatment product (baked product) of the composition for forming a passivation layer provided on the entire surface or a part of the semiconductor substrate. The semiconductor substrate with a passivation layer exhibits an excellent passivation effect by having a passivation layer that is a heat-treated product layer (baked product layer) of the composition for forming a passivation layer.

The semiconductor substrate is not particularly limited, and can be appropriately selected from those usually used according to the purpose. Examples of the semiconductor substrate include those obtained by doping (diffusing) p-type impurities or n-type impurities into silicon, germanium, or the like. Of these, a silicon substrate is preferable. The semiconductor substrate may be a p-type semiconductor substrate or an n-type semiconductor substrate. Among these, from the viewpoint of the passivation effect, it is preferable that the surface on which the passivation layer is formed is a semiconductor substrate having a p-type layer. Even if the p-type layer on the semiconductor substrate is a p-type layer derived from the p-type semiconductor substrate, the p-type layer is formed on the n-type semiconductor substrate or the p-type semiconductor substrate as a p-type diffusion layer or a p ⁺ -type diffusion layer. It may be a thing.

  The thickness in particular of a semiconductor substrate is not restrict | limited, According to the objective, it can select suitably. For example, the thickness of the semiconductor substrate can be 50 μm to 1000 μm, and preferably 75 μm to 750 μm.

  The thickness of the passivation layer formed on the semiconductor substrate is not particularly limited and can be appropriately selected depending on the purpose. For example, the thickness of the passivation layer is preferably 5 nm to 50 μm, more preferably 10 nm to 30 μm, and still more preferably 15 nm to 20 μm.

  The semiconductor substrate with a passivation layer can be applied to a solar cell element, a light emitting diode element, or the like. For example, the solar cell element excellent in conversion efficiency can be obtained by applying to a solar cell element.

<Method for manufacturing semiconductor substrate with passivation layer>
The method for producing a semiconductor substrate with a passivation layer according to the present invention includes a step of forming the composition layer by applying the composition for forming a passivation layer on the entire surface or a part of the semiconductor substrate, and heat-treating the composition layer ( Firing) to form a passivation layer. The manufacturing method may further include other steps as necessary.
By using the composition for forming a passivation layer of the present invention, a passivation layer having an excellent passivation effect can be formed into a desired shape by a simple method.

  It is preferable that the manufacturing method of the semiconductor substrate with a passivation layer further has the process of providing aqueous alkali solution on a semiconductor substrate before the process of forming a composition layer. That is, it is preferable to wash the surface of the semiconductor substrate with an alkaline aqueous solution before applying the composition for forming a passivation layer on the semiconductor substrate. By washing with an alkaline aqueous solution, organic substances, particles, and the like present on the surface of the semiconductor substrate can be removed, and the passivation effect is further improved. As a method for cleaning with an alkaline aqueous solution, generally known RCA cleaning and the like can be exemplified. For example, the semiconductor substrate can be washed by immersing the semiconductor substrate in a mixed solution of aqueous ammonia and hydrogen peroxide and treating at 60 ° C. to 80 ° C. to remove organic substances and particles. The washing time is preferably 10 seconds to 10 minutes, and more preferably 30 seconds to 5 minutes.

  There is no restriction | limiting in particular in the method of providing the composition for passivation layer formation on a semiconductor substrate, and forming a composition layer. For example, a method for applying a composition for forming a passivation layer on a semiconductor substrate using a known application method or the like can be mentioned. Specific examples include immersion method, printing, dispenser method, spin coating method, brush coating, spraying method, doctor blade method, roll coating method, and ink jet method. Among these, from the viewpoint of pattern formability, various printing methods (for example, screen printing), inkjet methods, and the like are preferable. The composition for forming a passivation layer of the present invention is excellent in printability and coating film uniformity even when applied to a printing method.

  The application amount of the composition for forming a passivation layer can be appropriately selected according to the purpose. For example, the thickness of the passivation layer to be formed can be appropriately adjusted so as to be a desired thickness described later.

A passivation layer is formed on a semiconductor substrate by heat-treating (baking) the composition layer formed by the composition for forming a passivation layer to form a heat-treated material layer (baked material layer) derived from the composition layer. be able to.
The heat treatment (firing) condition of the composition layer is a heat treated product (firing product) of the compound represented by the formula (I) contained in the composition layer and the compound represented by the general formula (II) contained as necessary. There is no particular limitation as long as it can be converted into a metal oxide or composite oxide. Among these, the heat treatment (firing) conditions that can form an amorphous metal oxide layer are preferable. When the passivation layer is composed of an amorphous metal oxide layer, the passivation layer can effectively have a negative charge, and a more excellent passivation effect can be obtained. Specifically, the heat treatment (firing) temperature is preferably 400 ° C to 900 ° C, more preferably 450 ° C to 800 ° C. The heat treatment (firing) temperature here means the maximum temperature in the furnace used for the heat treatment (firing). The heat treatment (firing) time can be appropriately selected according to the heat treatment (firing) temperature and the like. For example, it can be within 10 hours, preferably within 5 hours. The heat treatment (firing) time here means the holding time at the maximum temperature.

  In addition, heat processing (baking) can be performed using a diffusion furnace (For example, ACCURON CQ-1200, DD-200P, all are Hitachi Kokusai Electric; 206A-M100, Koyo Thermosystem Co., Ltd., etc.) etc. The atmosphere in which the heat treatment (firing) is performed is not particularly limited, and can be performed in the air.

The thickness of the passivation layer produced by the method for producing a semiconductor substrate with a passivation layer is not particularly limited and can be appropriately selected according to the purpose. For example, the average thickness of the passivation layer is preferably 5 nm to 50 μm, more preferably 10 nm to 30 μm, and still more preferably 15 nm to 20 μm.
The average thickness of the formed passivation layer is calculated as the arithmetic average value by measuring the thickness at three points by a conventional method using a stylus type step / surface shape measuring device (for example, Ambios). .

  A method of manufacturing a semiconductor substrate with a passivation layer includes: a composition layer comprising a composition for forming a passivation layer, after the composition for forming a passivation layer is applied to the semiconductor substrate and before the step of forming the passivation layer by heat treatment (firing). You may further have the process of drying-processing. By having a step of drying the composition layer, a passivation layer having a more uniform passivation effect can be formed.

  The step of drying the composition layer is not particularly limited as long as at least a part of the liquid medium that may be contained in the passivation layer forming composition can be removed. The drying treatment can be, for example, a heat treatment at 30 ° C. to 250 ° C. for 1 minute to 60 minutes, and is preferably a heat treatment at 40 ° C. to 220 ° C. for 3 minutes to 40 minutes. The drying treatment may be performed under normal pressure or under reduced pressure.

  In the case where the composition for forming a passivation layer contains a resin, the method for producing a semiconductor substrate with a passivation layer includes the step of forming a passivation layer after applying the composition for forming a passivation layer and before forming the passivation layer by heat treatment (firing). You may further have the process of degreasing the composition layer which consists of a composition for formation. By having a step of degreasing the composition layer, a passivation layer having a more uniform passivation effect can be formed.

  The step of degreasing the composition layer is not particularly limited as long as at least part of the resin that may be contained in the composition for forming a passivation layer can be removed. The degreasing treatment can be, for example, a heat treatment at 250 to 450 ° C. for 10 to 120 minutes, preferably a heat treatment at 300 to 400 ° C. for 3 to 60 minutes. The degreasing treatment is preferably performed in the presence of oxygen, and more preferably performed in the air.

<Solar cell element>
The solar cell element of the present invention includes a semiconductor substrate in which a p-type layer and an n-type layer are pn-junction, and a heat treatment product (baked product) of the passivation layer forming composition provided on the entire surface or a part of the semiconductor substrate. ) And an electrode disposed on one or more layers selected from the group consisting of the p-type layer and the n-type layer. The solar cell element may further include other components as necessary.
A solar cell element is excellent in conversion efficiency by having the passivation layer formed from the composition for passivation layer formation of this invention.

  It does not restrict | limit especially as a semiconductor substrate which provides the composition for formation of a passivation layer, According to the objective, it can select suitably from what is normally used. As a semiconductor substrate, what was demonstrated by the semiconductor substrate with a passivation layer can be used, and the thing which can be used conveniently is also the same. The surface of the semiconductor substrate on which the passivation layer is provided is preferably a p-type layer.

The thickness of the passivation layer formed on the semiconductor substrate is not particularly limited and can be appropriately selected depending on the purpose. For example, the average thickness of the passivation layer is preferably 5 nm to 50 μm, more preferably 10 nm to 30 μm, and still more preferably 15 nm to 20 μm.
There is no restriction | limiting in the shape and magnitude | size of a solar cell element. For example, it is preferable that one side is a substantially square of 125 mm to 156 mm.

<Method for producing solar cell element>
The method for manufacturing a solar cell element of the present invention has a pn junction formed by joining a p-type layer and an n-type layer, and is on one or more layers selected from the group consisting of the p-type layer and the n-type layer A step of forming the composition layer by applying the composition for forming a passivation layer on one or both of the surfaces having the electrodes of a semiconductor substrate having electrodes on the substrate, and heat-treating (firing) the composition layer And a step of forming a passivation layer. The manufacturing method of the solar cell element may further include other steps as necessary.

  By using the composition for forming a passivation layer, a solar cell element having a passivation layer having an excellent passivation effect and excellent in conversion efficiency can be produced by a simple method. Further, a passivation layer can be formed on the semiconductor substrate on which the electrode is formed so as to have a desired shape, and the productivity of the solar cell element is excellent.

  A semiconductor substrate having a pn junction in which an electrode is disposed on at least one of a p-type layer and an n-type layer can be manufactured by a commonly used method. For example, it can be manufactured by applying an electrode forming paste such as a silver paste or an aluminum paste to a desired region of a semiconductor substrate and performing a heat treatment (firing) as necessary.

The surface of the semiconductor substrate on which the passivation layer is provided may be a p-type layer or an n-type layer. Among these, a p-type layer is preferable from the viewpoint of conversion efficiency.
The details of the method for forming a passivation layer using the composition for forming a passivation layer are the same as the method for manufacturing a semiconductor substrate with a passivation layer described above, and the preferred embodiments are also the same.

  The thickness of the passivation layer formed on the semiconductor substrate is not particularly limited and can be appropriately selected depending on the purpose. For example, the average thickness of the passivation layer is preferably 5 nm to 50 μm, more preferably 10 nm to 30 μm, and still more preferably 15 nm to 20 μm.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view schematically showing an example of a method for producing a solar cell element having a passivation layer according to this embodiment. However, this process diagram does not limit the present invention at all.

As shown in FIG. 1A, in a p-type semiconductor substrate 1, an n ⁺ -type diffusion layer 2 is formed in the vicinity of the surface, and an antireflection film 3 is formed on the outermost surface. Examples of the antireflection film 3 include a silicon nitride film and a titanium oxide film. A surface protective film (not shown) such as silicon oxide may further exist between the antireflection film 3 and the p-type semiconductor substrate 1. Moreover, you may use the passivation layer concerning this invention as a surface protective film.

Next, as shown in FIG. 1B, a material for forming the back electrode 5 such as an aluminum electrode paste is applied to a part of the back surface, and then heat-treated (fired) to form the back electrode 5, and p A p ⁺ type diffusion layer 4 is formed by diffusing aluminum atoms in the type semiconductor substrate 1.

Next, as shown in FIG. 1C, the electrode-forming paste is applied to the light-receiving surface side, and then heat-treated (fired) to form the light-receiving surface electrode 7. By using those containing glass powder having a fire-through property as an electrode forming paste, reaches through the antireflective film 3, as shown in FIG. 1 (c), on the n ⁺ -type diffusion layer 2, the light-receiving surface The electrode 7 can be formed to obtain an ohmic contact.

  And as shown in FIG.1 (d), the composition for passivation layer formation is provided by screen printing etc. on the p-type layer of the back surface other than the area | region in which the back electrode 5 was formed, and a composition layer is formed. . The passivation layer 6 is formed by heat-treating (baking) the composition layer formed on the p-type layer. By forming the passivation layer 6 formed from the composition for forming a passivation layer of the present invention on the p-type layer on the back surface, a solar cell element excellent in power generation efficiency can be manufactured.

  In the solar cell element manufactured by the manufacturing method including the manufacturing process shown in FIG. 1, the back electrode formed from aluminum or the like can have a point contact structure, and the warpage of the substrate can be reduced. Furthermore, by using the composition for forming a passivation layer, the passivation layer can be formed with excellent productivity at a specific position (specifically, on the p-type layer other than the region where the electrode is formed).

Further, FIG. 1D shows a method of forming a passivation layer only on the back surface portion. However, in addition to the back surface side of the p-type semiconductor substrate 1, a passivation layer forming composition is applied to the side surface, and this is subjected to heat treatment. The passivation layer 6 may be further formed on the side surface (edge) of the semiconductor substrate 1 by (baking) (not shown). Thereby, the solar cell element excellent in power generation efficiency can be manufactured.
Furthermore, the passivation layer 6 may be formed by forming the passivation layer forming composition of the present invention only on the side surface without forming the passivation layer on the back surface portion, and performing heat treatment (firing). When the composition for forming a passivation layer of the present invention is used in a portion having many crystal defects such as side surfaces, the effect is particularly great.

  Although the embodiment in which the passivation layer is formed after forming the electrode has been described with reference to FIG. 1, an electrode such as aluminum may be further formed in a desired region by vapor deposition or the like after the passivation layer is formed.

FIG. 2 is a cross-sectional view schematically showing another process example of a method for manufacturing a solar cell element having a passivation layer according to the present embodiment. Specifically, FIG. 2 shows the heat treatment of the aluminum electrode paste after forming the p ⁺ type diffusion layer using the aluminum electrode paste or the p type diffusion layer forming composition capable of forming the p ⁺ type diffusion layer by thermal diffusion treatment. The process drawing including the process of removing the heat-treated product of the product or the p ⁺ -type diffusion layer forming composition will be described as a cross-sectional view. Examples of the p-type diffusion layer forming composition include a composition containing an acceptor element-containing substance and a glass component.

As shown in FIG. 2A, an n ⁺ -type diffusion layer 2 is formed in the vicinity of the surface of the p-type semiconductor substrate 1, and an antireflection film 3 is formed on the surface. Examples of the antireflection film 3 include a silicon nitride film and a titanium oxide film.

Next, as shown in FIG. 2 (b), the p ⁺ -type diffusion layer 4 is formed by applying a p-type diffusion layer forming composition to a partial region of the back surface and then performing heat treatment. On the p ⁺ type diffusion layer 4, a heat treatment product 8 of a composition for forming a p type diffusion layer is formed.
Here, an aluminum electrode paste may be used instead of the p-type diffusion layer forming composition. When an aluminum electrode paste is used, an aluminum electrode 8 is formed on the p ⁺ type diffusion layer 4.

Next, as shown in FIG. 2C, the heat-treated product 8 or the aluminum electrode 8 of the p-type diffusion layer forming composition formed on the p ⁺ -type diffusion layer 4 is removed by a technique such as etching.

Next, as shown in FIG. 2 (d), the electrode forming paste is selectively applied to the light receiving surface (front surface) and a part of the back surface, and then heat-treated, and the light receiving surface electrode 7 is applied to the light receiving surface (front surface). The back electrode 5 is formed on the back surface. By using a paste containing a glass powder having fire-through property as an electrode forming paste to be applied to the light receiving surface side, as shown in FIG. 2C, the antireflection film 3 is penetrated to form an n ⁺ type diffusion layer. The light-receiving surface electrode 7 is formed on the surface 2 and an ohmic contact can be obtained.
Further, since the p ⁺ -type diffusion layer 4 is already formed in the region where the back electrode is formed, the electrode forming paste for forming the back electrode 5 is not limited to the aluminum electrode paste, but may be a silver electrode paste or the like. An electrode paste capable of forming a lower resistance electrode can also be used. As a result, the power generation efficiency can be further increased.

And as shown in FIG.2 (e), the composition for passivation layer formation is provided on the p-type layer of the back surface other than the area | region in which the back electrode 5 was formed, and a composition layer is formed. The application can be performed by a method such as screen printing. The passivation layer 6 is formed by heat-treating (firing) the composition layer formed on the p ⁺ -type diffusion layer 4. By forming the passivation layer 6 formed from the composition for forming a passivation layer of the present invention on the p-type layer on the back surface, a solar cell element excellent in power generation efficiency can be manufactured.

  Further, FIG. 2E shows a method of forming a passivation layer only on the back surface portion, but in addition to the back surface side of the p-type semiconductor substrate 1, a passivation layer material is also applied to the side surface and heat treatment (firing) is performed. Thus, a passivation layer may be further formed on the side surface (edge) of the p-type semiconductor substrate 1 (not shown). Thereby, the solar cell element which was further excellent in power generation efficiency can be manufactured.

  Furthermore, the passivation layer may be formed by applying the composition for forming a passivation layer of the present invention only to the side surface without forming the passivation layer on the back surface portion, and heat-treating (baking) the composition. When the composition for forming a passivation layer of the present invention is used in a portion having many crystal defects such as side surfaces, the effect is particularly great.

  In FIG. 2, the embodiment in which the passivation layer is formed after the electrode is formed has been described. However, after the passivation layer is formed, an electrode such as aluminum may be further formed in a desired region by vapor deposition or the like.

In the embodiment described above, the case where a p-type semiconductor substrate having an n ⁺ -type diffusion layer formed on the light-receiving surface has been described. However, an n-type semiconductor substrate having a p ⁺ -type diffusion layer formed on the light-receiving surface is described. Similarly, when used, a solar cell element can be produced. In this case, an n ⁺ type diffusion layer is formed on the back side.

Furthermore, the composition for forming a passivation layer can also be used to form a passivation layer 6 on the light receiving surface side or the back surface side of a back electrode type solar cell element in which an electrode is disposed only on the back surface side as shown in FIG.
As shown in a schematic cross-sectional view in FIG. 3, an n ⁺ -type diffusion layer 2 is formed in the vicinity of the surface on the light-receiving surface side of the p-type semiconductor substrate 1, and a passivation layer 6 and an antireflection film 3 are formed on the surface. ing. As the antireflection film 3, a silicon nitride film, a titanium oxide film, or the like is known. The passivation layer 6 is formed by applying the passivation layer forming composition of the present invention and heat-treating (firing) it.

On the back side of the p-type semiconductor substrate 1, a back electrode 5 is provided on each of the p ⁺ -type diffusion layer 4 and the n ⁺ -type diffusion layer 2, and a passivation layer 6 is provided in a region where no back-side electrode is formed. Is provided.
The p ⁺ -type diffusion layer 4 can be formed by applying a heat treatment after applying the p-type diffusion layer forming composition or the aluminum electrode paste to a desired region as described above. The n ⁺ -type diffusion layer 2 can be formed by, for example, applying a composition for forming an n-type diffusion layer capable of forming an n ⁺ -type diffusion layer to a desired region by heat diffusion treatment and then performing a heat treatment.
Examples of the composition for forming an n-type diffusion layer include a composition containing a donor element-containing material and a glass component.

The back electrode 5 provided on each of the p ⁺ type diffusion layer 4 and the n ⁺ type diffusion layer 2 can be formed using a commonly used electrode forming paste such as a silver electrode paste.
The back electrode 5 provided on the p ⁺ -type diffusion layer 4 may be an aluminum electrode formed with the p ⁺ -type diffusion layer 4 using aluminum electrode paste.
The passivation layer 6 provided on the back surface can be formed by applying a composition for forming a passivation layer to a region where the back electrode 5 is not provided and heat-treating (baking) the composition.
Further, the passivation layer 6 may be formed not only on the back surface of the p-type semiconductor substrate 1 but also on the side surface (not shown).

  In the back electrode type solar cell element as shown in FIG. 3, since there is no electrode on the light receiving surface side, the power generation efficiency is excellent. Furthermore, since the passivation layer is formed in the region where the back electrode is not formed, the conversion efficiency is further improved.

  Although the example which used the p-type semiconductor substrate as the semiconductor substrate was shown above, also when an n-type semiconductor substrate is used, the solar cell element which is excellent in conversion efficiency according to the above can be manufactured.

<Solar cell>
The solar cell includes the solar cell element and a wiring material provided on the electrode of the solar cell element. If necessary, the solar cell may be constituted by connecting a plurality of solar cell elements via a wiring material such as a tab wire and further sealing with a sealing material. The wiring material and the sealing material are not particularly limited, and can be appropriately selected from those usually used in the industry. There is no limit to the size of the solar cell. It is preferably 0.5m ² ~3m ^2.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

<Example 1>
(Preparation of composition 1 for forming a passivation layer)
A stearamide solution was prepared by mixing 5.0 g of stearamide and 45.0 g of terpineol and stirring at 130 ° C. for 1 hour. 10.01 g of ethyl cellulose and 90.02 g of terpineol were mixed and stirred at 150 ° C. for 1 hour to prepare an ethyl cellulose solution. Passivation layer: 2.22 g of niobium ethoxide, 2.23 g of (ethylacetoacetate) aluminum isopropoxide, 1.88 g of terpineol, 1.58 g of stearamide solution, and 7.92 g of ethylcellulose solution. A forming composition 1 was prepared. The content of stearamide in the composition 1 for forming a passivation layer was 1.0%, and the content of the compound of formula (I) was 14.0%.

(Evaluation of storage stability)
The shear viscosity of the composition 1 for forming a passivation layer prepared above was measured immediately after preparation (within 12 hours) and after storage at 25 ° C. for 30 days, respectively. The shear viscosity was measured by attaching a cone plate (diameter 50 nm, cone angle 1 °) to Anton Paar, MCR301, at a temperature of 25 ° C. and a shear rate of 1.0 s ⁻¹ . The shear viscosity at 25 ° C. was 28.2 Pa · s immediately after preparation, and 29.8 Pa · s after storage at 25 ° C. for 30 days.

(Formation of passivation layer)
As the semiconductor substrate, a single crystal p-type silicon substrate (SUMCO, 50 mm square, thickness: 770 μm) having a mirror-shaped surface was used. The composition 1 for forming a passivation layer obtained above was applied onto a silicon substrate using a screen printing method. The composition 1 for forming a passivation layer was applied in such an amount that the average thickness of the passivation layer obtained after heat treatment (firing) was 300 μm.
The above printing was performed 10 times continuously, and it was visually confirmed that no printing unevenness was found on all 10 sheets. The printing unevenness refers to a portion that is formed thinner than the surroundings because a part of the screen plate is poorly separated when the screen plate is separated from the silicon substrate.

Moreover, it was visually confirmed similarly that the coated film after printing was 9 out of 10 sheets. The state where the coating film is uniform means that the composition for forming a passivation layer is present on the entire printed portion on the silicon substrate. Thereafter, the silicon substrate provided with the passivation layer forming composition 1 was dried at 150 ° C. for 5 minutes. Next, the substrate was heat-treated (fired) at 700 ° C. for 10 minutes and then allowed to cool at room temperature to produce an evaluation substrate. Heat treatment (firing) is carried out using a diffusion furnace (horizontal diffusion furnace DD-200P, Hitachi Kokusai Electric Inc.) under atmospheric conditions (flow rate: 5 L / min), a maximum temperature of 700 ° C., and a holding time of 10 minutes. went.
The average thickness of the obtained passivation layer was calculated as an arithmetic average value by measuring the thickness at three points by a conventional method using a stylus type step / surface shape measuring device (Ambios).

(Measurement of effective lifetime)
The effective lifetime (μs) of the region where the passivation layer of the evaluation substrate obtained above is formed is quasi-stationary at room temperature (25 ° C.) using a lifetime measuring device (Sinton Instruments, WCT-120). Measured by state photoconductivity method. The effective lifetime was 880 μs.

<Example 2>
A polyethylene glycol solution was prepared by mixing 5.0 g of polyethylene glycol (number average molecular weight 4000) and 45.0 g of terpineol and stirring at 100 ° C. for 1 hour. Formation of a passivation layer by mixing 2.11 g of niobium ethoxide, 2.17 g of (ethylacetoacetato) aluminum isopropoxide, 1.75 g of terpineol, 1.51 g of polyethylene glycol solution, and 7.55 g of ethyl cellulose solution Composition 2 was prepared. The content of polyethylene glycol in the composition 2 for forming a passivation layer was 1.0%, and the content of the compound of formula (I) was 14.0%. The viscosity of the composition 2 for forming a passivation layer 2 was 35.5 Pa · s immediately after preparation and 37.8 Pa · s after storage at 25 ° C. for 30 days.

  A passivation layer was formed on a silicon substrate in the same manner as in Example 1 except that the composition 2 for forming a passivation layer prepared above was used, and evaluated in the same manner. Of the 10 screen prints, 9 had no printing unevenness. Of the 10 sheets, 7 were uniform. The effective lifetime was 801 μs.

<Example 3>
2.12 g of niobium ethoxide, 2.18 g of (ethylacetoacetate) aluminum isopropoxide, 1.80 g of terpineol, MR-2G (organic filler, Soken Chemical Co., Ltd., PMMA resin filler, volume average particle size 1 1.0 μm) and 7.61 g of ethyl cellulose solution were mixed to prepare a passivation layer forming composition 3. The content of MR-2G (denoted as MR in the table) in the composition 3 for forming a passivation layer of MR was 9.9%, and the content of the compound of formula (I) was 13.9%. The viscosity of the composition 3 for forming a passivation layer 3 was 28.2 Pa · s immediately after preparation and 32.3 Pa · s after storage at 25 ° C. for 30 days.

  A passivation layer was formed on a silicon substrate in the same manner as in Example 1 except that the composition 3 for forming a passivation layer prepared above was used, and evaluated in the same manner. Of the 10 screen prints, 10 had no printing unevenness. Of the 10 sheets, 10 were uniform. The effective lifetime was 627 μs.

<Comparative Example 1>
In Example 1, a substrate for evaluation was prepared, and the effective lifetime was measured and evaluated in the same manner as in Example 1 except that the composition 1 for forming a passivation layer 1 was not applied. The effective lifetime was 20 μs.

<Comparative example 2>
2.10 g of niobium ethoxide, 2.17 g of (ethylacetoaceto) aluminum isopropoxide, 3.31 g of terpineol, and 7.63 g of ethylcellulose solution were mixed to prepare composition C1. The viscosity of the composition C1 was 23.5 Pa · s immediately after preparation, and 24.8 Pa · s after storage at 25 ° C. for 30 days.

A passivation layer was formed on a silicon substrate in the same manner as in Example 1 except that the composition C1 prepared above was used, and evaluated in the same manner. Of the 10 screen prints, 4 had no printing unevenness. Of the 10 sheets, the number of the coated films was uniform. The effective lifetime was 1077 μs.

<Comparative Example 3>
0.80 g of stearamide solution and 7.81 g of ethylcellulose solution were mixed to prepare composition C2. The viscosity of the composition C2 was 27.2 Pa · s immediately after preparation and 28.0 Pa · s after storage at 25 ° C. for 30 days.

  A passivation layer was formed on a silicon substrate in the same manner as in Example 1 except that the composition C2 prepared above was used, and evaluated in the same manner. Of the 10 screen prints, 9 had no printing unevenness. Of the 10 sheets, 9 were uniform. The effective lifetime was 24 μs.

<Comparative Example 4>
2.13 g of niobium chloride, 2.14 g of (ethylacetoacetate) aluminum isopropoxide, 1.79 g of terpineol, 1.55 g of stearamide solution, and 7.84 g of ethylcellulose solution were mixed to obtain composition C3 Was prepared. The viscosity of the composition C1 was 28.6 Pa · s immediately after preparation, and 58.4 Pa · s after storage at 25 ° C. for 30 days.

The above results are summarized in the following table.
In the storage stability item in the table, the change rate of shear viscosity after storage for 30 days is less than 10%, A is 10% or more and less than 30%, B is 30% or more, and C is marked. To do. If evaluation is A and B, it is favorable as the storage stability of the composition for forming a passivation layer.
Also, in the printability item, 9 or more out of 10 sheets that did not cause printing unevenness during printing were A, 8 or less and 6 or more B, and 5 or less. Indicated as C.
In addition, in the item of coating film uniformity, when the coating film was visually uniform after printing, 9 out of 10 sheets were A, 8 sheets or less and 6 sheets or more were B, 5 sheets or less The thing is written as C.

  From the above, it can be seen that the composition for forming a passivation layer of the present invention is excellent in storage stability. Moreover, it turns out that the passivation layer which has the outstanding passivation effect can be formed by using the composition for passivation layer formation of this invention. Moreover, it turns out that a passivation layer can be formed in a desired shape by a simple process by using the composition for forming a passivation layer of the present invention. Furthermore, it turns out that the composition for formation of the passivation layer of Examples 1-3 is excellent in printability and a coating-film uniformity.

<Reference Embodiment 1>
The following are the passivation film, the coating material, the solar cell element, and the silicon substrate with the passivation film according to Reference Embodiment 1.

<1> A passivation film used for a solar cell element including aluminum oxide and niobium oxide and having a silicon substrate.

<2> The passivation film according to <1>, wherein a mass ratio (niobium oxide / aluminum oxide) between the niobium oxide and the aluminum oxide is 30/70 to 90/10.

<3> The passivation film according to <1> or <2>, wherein a total content of the niobium oxide and the aluminum oxide is 90% by mass or more.

<4> The passivation film according to any one of <1> to <3>, further including an organic component.

<5> The passivation film according to any one of <1> to <4>, which is a heat-treated product of a coating material containing an aluminum oxide precursor and a niobium oxide precursor.

<6> A coating-type material that includes an aluminum oxide precursor and a niobium oxide precursor and is used to form a passivation film for a solar cell element having a silicon substrate.

<7> A p-type silicon substrate made of single crystal silicon or polycrystalline silicon and having a light receiving surface and a back surface opposite to the light receiving surface;
An n-type impurity diffusion layer formed on the light-receiving surface side of the silicon substrate;
A first electrode formed on the surface of the n-type impurity diffusion layer on the light-receiving surface side of the silicon substrate;
A passivation film comprising aluminum oxide and niobium oxide formed on the back surface of the silicon substrate and having a plurality of openings;
A second electrode forming an electrical connection with the surface on the back side of the silicon substrate through the plurality of openings;
A solar cell element comprising:

<8> A p-type silicon substrate made of single crystal silicon or polycrystalline silicon and having a light receiving surface and a back surface opposite to the light receiving surface;
An n-type impurity diffusion layer formed on the light-receiving surface side of the silicon substrate;
A first electrode formed on the surface of the n-type impurity diffusion layer on the light-receiving surface side of the silicon substrate;
A p-type impurity diffusion layer formed on a part or all of the back side of the silicon substrate and doped with impurities at a higher concentration than the silicon substrate;
A passivation film comprising aluminum oxide and niobium oxide formed on the back surface of the silicon substrate and having a plurality of openings;
A second electrode that forms an electrical connection with the surface of the p-type impurity diffusion layer on the back side of the silicon substrate through the plurality of openings;
A solar cell element comprising:

<9> An n-type silicon substrate made of single crystal silicon or polycrystalline silicon and having a light receiving surface and a back surface opposite to the light receiving surface;
A p-type impurity diffusion layer formed on the light-receiving surface side of the silicon substrate;
A second electrode formed on the back side of the silicon substrate;
A passivation film formed on the light-receiving surface side surface of the silicon substrate and including a plurality of openings and containing aluminum oxide and niobium oxide;
A first electrode formed on the surface of the p-type impurity diffusion layer on the light-receiving surface side of the silicon substrate and forming an electrical connection with the surface on the light-receiving surface side of the silicon substrate through the plurality of openings; ,
A solar cell element comprising:

<10> The solar cell element according to any one of <7> to <9>, wherein the mass ratio of niobium oxide to aluminum oxide (niobium oxide / aluminum oxide) in the passivation film is 30/70 to 90/10.

<11> The solar cell element according to any one of <7> to <10>, wherein a total content of the niobium oxide and the aluminum oxide in the passivation film is 90% by mass or more.

<12> a silicon substrate;
The passivation film according to any one of <1> to <5> provided on the entire surface or a part of the silicon substrate;
A silicon substrate with a passivation film.

  According to the reference embodiment described above, a passivation film having a long silicon carrier lifetime and a negative fixed charge can be realized at a low cost. In addition, a coating type material for realizing the formation of the passivation film can be provided. In addition, a highly efficient solar cell element using the passivation film can be realized at low cost. In addition, a silicon substrate with a passivation film having a long carrier lifetime and a negative fixed charge can be realized at low cost.

  The passivation film of the present embodiment is a passivation film used for a silicon solar cell element, and includes aluminum oxide and niobium oxide.

  In this embodiment mode, the fixed charge amount of the film can be controlled by changing the composition of the passivation film.

  Further, it is more preferable that the mass ratio of niobium oxide and aluminum oxide is 30/70 to 80/20 from the viewpoint that the negative fixed charge can be stabilized. Further, the mass ratio of niobium oxide and aluminum oxide is more preferably 35/65 to 70/30 from the viewpoint that the negative fixed charge can be further stabilized. In addition, it is preferable that the mass ratio of niobium oxide and aluminum oxide is 50/50 to 90/10 from the viewpoint that both improvement of carrier lifetime and negative fixed charge can be achieved.

  The mass ratio of niobium oxide to aluminum oxide in the passivation film is measured by energy dispersive X-ray spectroscopy (EDX), secondary ion mass spectrometry (SIMS), and high frequency inductively coupled plasma mass spectrometry (ICP-MS). be able to. Specific measurement conditions are as follows. Dissolving the passivation film in acid or alkaline aqueous solution, atomizing this solution and introducing it into Ar plasma, measuring the wavelength and intensity by spectroscopically analyzing the light emitted when the excited element returns to the ground state, Element qualification is performed from the obtained wavelength, and quantification is performed from the obtained intensity.

  The total content of niobium oxide and aluminum oxide in the passivation film is preferably 80% by mass or more, and more preferably 90% by mass or more from the viewpoint of maintaining good characteristics. As the components of niobium oxide and aluminum oxide in the passivation film increase, the effect of negative fixed charges increases.

  The total content of niobium oxide and aluminum oxide in the passivation film can be measured by combining thermogravimetric analysis, fluorescent X-ray analysis, ICP-MS, and X-ray absorption spectroscopy. Specific measurement conditions are as follows. The ratio of inorganic components can be calculated by thermogravimetric analysis, the ratio of niobium and aluminum can be calculated by fluorescent X-ray or ICP-MS analysis, and the ratio of oxide can be examined by X-ray absorption spectroscopy.

  Further, the passivation film may contain components other than niobium oxide and aluminum oxide as organic components from the viewpoint of improving the film quality and adjusting the elastic modulus. The presence of the organic component in the passivation film can be confirmed by elemental analysis and measurement of the FT-IR of the film.

  The content of the organic component in the passivation film is more preferably less than 10% by mass, further preferably 5% by mass or less, and particularly preferably 1% by mass or less in the passivation film.

  The passivation film may be obtained as a heat-treated product of a coating type material containing an aluminum oxide precursor and a niobium oxide precursor. Details of the coating type material will be described next.

  The coating material of the present embodiment includes an aluminum oxide precursor and a niobium oxide precursor, and is used for forming a passivation film for a solar cell element having a silicon substrate.

The aluminum oxide precursor can be used without particular limitation as long as it produces aluminum oxide. As the aluminum oxide precursor, it is preferable to use an organic aluminum oxide precursor from the viewpoint of uniformly dispersing aluminum oxide on the silicon substrate and chemically stable. Examples of the organic aluminum oxide precursor include aluminum triisopropoxide (structural formula: Al (OCH (CH ₃ ) ₂ ) ₃ , High Purity Chemical Research Laboratory SYM-AL04, and the like.

The niobium oxide precursor can be used without particular limitation as long as it produces niobium oxide. As the niobium oxide precursor, it is preferable to use an organic niobium oxide precursor from the viewpoint of uniformly dispersing niobium oxide on the silicon substrate and chemically stable. Examples of organic niobium oxide precursors include niobium (V) ethoxide (structural formula: Nb (OC ₂ H ₅ ) ₅ , molecular weight: 318.21), High Purity Chemical Laboratory Nb-05, etc. be able to.

  A passivation film is formed by forming a coating type material containing an organic niobium oxide precursor and an organic aluminum oxide precursor using a coating method or a printing method, and then removing organic components by a subsequent heat treatment (firing). Can be obtained. Therefore, as a result, a passivation film containing an organic component may be used.

<Structure explanation of solar cell element>
The structure of the solar cell element of the present embodiment will be described with reference to FIGS. 5-8 is sectional drawing which shows the 1st-4th structural example of the solar cell element which used the passivation film for the back surface of this Embodiment.

  As the silicon substrate (crystalline silicon substrate, semiconductor substrate) 101 used in this embodiment mode, either single crystal silicon or polycrystalline silicon may be used. Further, as the silicon substrate 101, either p-type crystalline silicon or n-type crystalline silicon may be used. From the standpoint of exerting the effects of the present embodiment, p-type crystalline silicon is more suitable.

  5 to 8 below, an example in which p-type single crystal silicon is used as the silicon substrate 101 will be described. Note that single crystal silicon or polycrystalline silicon used for the silicon substrate 101 may be any material, but single crystal silicon or polycrystalline silicon having a resistivity of 0.5 Ω · cm to 10 Ω · cm is preferable.

  As shown in FIG. 5 (first configuration example), an n-type diffusion layer 102 doped with a group V element such as phosphorus on the light-receiving surface side (upper side, first surface in the figure) of a p-type silicon substrate 101. Is formed. A pn junction is formed between the silicon substrate 101 and the diffusion layer 102. On the surface of the diffusion layer 102, a light receiving surface antireflection film 103 such as a silicon nitride (SiN) film, and a first electrode 105 (light receiving surface side electrode, first surface electrode, upper surface electrode) using silver (Ag) or the like. , A light receiving surface electrode) is formed. The light receiving surface antireflection film 103 may also have a function as a light receiving surface passivation film. By using the SiN film, both functions of the light receiving surface antireflection film and the light receiving surface passivation film can be provided.

  Note that the solar cell element of the present embodiment may or may not have the light-receiving surface antireflection film 103. In addition, the light receiving surface of the solar cell element is preferably formed with a concavo-convex structure (texture structure) in order to reduce the reflectance on the surface, but the solar cell element of the present embodiment has a texture structure. It may or may not have.

  On the other hand, a BSF (Back Surface Field) layer 104, which is a layer doped with a group III element such as aluminum or boron, is formed on the back side (lower side, second side, back side in the figure) of the silicon substrate 101. . However, the solar cell element of this embodiment may or may not have the BSF layer 104.

  A second surface made of aluminum or the like is used on the back surface side of the silicon substrate 101 to make contact (electrical connection) with the BSF layer 104 (or the surface on the back surface side of the silicon substrate 101 when the BSF layer 104 is not provided). Electrodes 106 (back side electrode, second side electrode, back side electrode) are formed.

  Further, in FIG. 5 (first configuration example), a contact region (a surface on the back side of the silicon substrate 101 when the BSF layer 104 is not provided) and the second electrode 106 are electrically connected ( A passivation film (passivation layer) 107 containing aluminum oxide and niobium oxide is formed in a portion excluding the opening OA). The passivation film 107 of this embodiment can have a negative fixed charge. With this fixed charge, electrons which are minority carriers among the carriers generated in the silicon substrate 101 by light are bounced back to the surface side. For this reason, a short circuit current increases and it is anticipated that photoelectric conversion efficiency will improve.

  Next, a second configuration example shown in FIG. 6 will be described. In FIG. 5 (first configuration example), the second electrode 106 is formed on the entire surface of the contact region (opening OA) and the passivation film 107, but in FIG. 6 (second configuration example) The second electrode 106 is formed only in the region (opening OA). The second electrode 106 may be formed only in part on the contact region (opening OA) and the passivation film 107. Even with the solar cell element having the configuration shown in FIG. 6, the same effect as in FIG. 5 (first configuration example) can be obtained.

  Next, a third configuration example shown in FIG. 7 will be described. In the third configuration example shown in FIG. 7, the BSF layer 104 is formed only on a part of the back surface side including the contact region (opening OA portion) with the second electrode 106, and FIG. 5 (first configuration example). Thus, it is not formed on the entire back surface side. Even with the solar cell element having such a configuration (FIG. 7), the same effect as that of FIG. 5 (first configuration example) can be obtained. Further, according to the solar cell element of the third configuration example of FIG. 7, impurities are doped at a higher concentration than the silicon substrate 101 by doping the BSF layer 104, that is, a group III element such as aluminum or boron. Since the area is small, it is possible to obtain higher photoelectric conversion efficiency than that in FIG. 5 (first configuration example).

  Next, a fourth configuration example shown in FIG. 8 will be described. In FIG. 7 (third configuration example), the second electrode 106 is formed on the entire surface of the contact region (opening OA) and the passivation film 107, but in FIG. 8 (fourth configuration example), the contact is formed. The second electrode 106 is formed only in the region (opening OA). The second electrode 106 may be formed only in part on the contact region (opening OA) and the passivation film 107. Even with the solar cell element having the configuration shown in FIG. 8, the same effect as that of FIG. 7 (third configuration example) can be obtained.

  In addition, when the second electrode 106 is applied by a printing method and baked at a high temperature to form the entire surface on the back surface side, a convex warpage tends to occur in the temperature lowering process. Such warpage may cause damage to the solar cell element, which may reduce the yield. Further, the problem of warpage increases as the silicon substrate becomes thinner. The cause of this warp is that stress is generated because the thermal expansion coefficient of the second electrode 106 made of metal (for example, aluminum) is larger than that of the silicon substrate, and the shrinkage in the temperature lowering process is correspondingly large.

  From the above, when the second electrode 106 is not formed on the entire back surface side as shown in FIG. 6 (second configuration example) and FIG. 8 (fourth configuration example), the electrode structure tends to be symmetrical vertically. This is preferable because stress due to the difference in thermal expansion coefficient is unlikely to occur. However, in that case, it is preferable to provide a separate reflective layer.

<Description of manufacturing method of solar cell element>
Next, an example of a method for manufacturing the solar cell element (FIGS. 5 to 8) of the present embodiment having the above-described configuration will be described. However, the present embodiment is not limited to the solar cell element manufactured by the method described below.

  First, a texture structure is formed on the surface of the silicon substrate 101 shown in FIG. The texture structure may be formed on both sides of the silicon substrate 101 or only on one side (light receiving side). In order to form a texture structure, first, the damaged layer of the silicon substrate 101 is removed by immersing the silicon substrate 101 in a heated potassium hydroxide or sodium hydroxide solution. Then, a texture structure is formed on both surfaces or one surface (light receiving surface side) of the silicon substrate 101 by dipping in a solution containing potassium hydroxide and isopropyl alcohol as main components. In addition, as above-mentioned, since the solar cell element of this Embodiment does not have to have a texture structure, you may abbreviate | omit this process.

Subsequently, after the silicon substrate 101 is washed with a solution of hydrochloric acid, hydrofluoric acid, etc., a phosphorus diffusion layer (n ⁺ layer) is formed as the diffusion layer 102 by thermal diffusion of phosphorus oxychloride (POCl ₃ ) or the like on the silicon substrate 101. To do. The phosphorus diffusion layer can be formed, for example, by applying a coating-type doping material solution containing phosphorus to the silicon substrate 101 and performing heat treatment. After the heat treatment, the phosphorous glass layer formed on the surface is removed with an acid such as hydrofluoric acid, whereby a phosphorous diffusion layer (n ⁺ layer) is formed as the diffusion layer 102. The method for forming the phosphorus diffusion layer is not particularly limited. The phosphorus diffusion layer may be formed so that the depth from the surface of the silicon substrate 101 is in the range of 0.2 μm to 0.5 μm, and the sheet resistance is in the range of 40Ω / □ to 100Ω / □ (ohm / square). preferable.

Thereafter, a BSF layer 104 on the back surface side is formed by applying a coating-type doping material solution containing boron, aluminum or the like to the back surface side of the silicon substrate 101 and performing heat treatment. For the application, methods such as screen printing, inkjet, dispensing, spin coating and the like can be used. After the heat treatment, the BSF layer 104 is formed by removing a layer of boron glass, aluminum, or the like formed on the back surface with hydrofluoric acid, hydrochloric acid, or the like. The method for forming the BSF layer 104 is not particularly limited. Preferably, the BSF layer 104 is preferably formed such that the concentration range of boron, aluminum, or the like is 10 ¹⁸ cm ⁻³ to 10 ²² cm ^−3, and the BSF layer 104 is formed in a dot shape or a line shape It is preferable to do. Note that the solar cell element of the present embodiment may or may not have the BSF layer 104, and thus this step may be omitted.

Further, when the diffusion layer 102 on the light-receiving surface and the BSF layer 104 on the back surface are formed using a coating-type doping material solution, the above-described doping material solution is applied to both sides of the silicon substrate 101 to diffuse. The phosphorous diffusion layer (n ⁺ layer) and the BSF layer 104 as the layer 102 may be formed in a lump, and then phosphorous glass, boron glass, or the like formed on the surface may be removed all at once.

Thereafter, a silicon nitride film as the light-receiving surface antireflection film 103 is formed on the diffusion layer 102. The method for forming the light receiving surface antireflection film 103 is not particularly limited. The light-receiving surface antireflection film 103 is preferably formed to have a thickness in the range of 50 to 100 nm and a refractive index in the range of 1.9 to 2.2. The light-receiving surface antireflection film 103 is not limited to a silicon nitride film, and may be a silicon oxide film, an aluminum oxide film, a titanium oxide film, or the like. Receiving surface antireflection film 103 such as a nitride silicic Motomaku a plasma CVD, can be manufactured by a method such as thermal CVD, it is preferably prepared in a form capable of plasma CVD at a temperature range of 350 ° C. to 500 ° C..

  Next, a passivation film 107 is formed on the back side of the silicon substrate 101. The passivation film 107 contains aluminum oxide and niobium oxide. For example, an aluminum oxide precursor typified by an organometallic decomposition coating material from which aluminum oxide can be obtained by heat treatment (firing), and niobium oxide obtained by heat treatment (firing). It is formed by applying a material (passivation material) containing a niobium oxide precursor typified by a commercially available organometallic decomposition coating type material and heat-treating (firing).

  The formation of the passivation film 107 can be performed as follows, for example. The above coating material is spin-coated on one side of a 725 μm thick 8-inch (20.32 cm) p-type silicon substrate (8 Ωcm to 12 Ωcm) from which a natural oxide film has been previously removed with hydrofluoric acid having a concentration of 0.049% by mass. Then, pre-baking is performed on a hot plate at 120 ° C. for 3 minutes. Thereafter, heat treatment is performed at 650 ° C. for 1 hour in a nitrogen atmosphere. In this case, a passivation film containing aluminum oxide and niobium oxide is obtained. The thickness of the passivation film 107 formed by the above method is usually about several tens of nanometers as measured by an ellipsometer.

  The coating material is applied to a predetermined pattern including the contact region (opening OA) by a method such as screen printing, offset printing, ink jet printing, or dispenser printing. In addition, after apply | coating the said coating type material, after pre-baking in the range of 80 to 180 degreeC and evaporating a solvent, in nitrogen atmosphere or in air, it is 600 to 1000 degreeC, and 30 minutes to 3 hours. It is preferable to perform a degree of heat treatment (annealing) to form a passivation film 107 (oxide film).

  Furthermore, the opening (contact hole) OA is preferably formed on the BSF layer 104 in a dot shape or a line shape.

  As the passivation film 107 used for the above solar cell element, the mass ratio of niobium oxide to aluminum oxide (niobium oxide / aluminum oxide) is preferably 30/70 to 90/10, and 30/70 to 80/20. More preferably, it is more preferably 35/65 to 70/30. Thereby, the negative fixed charge can be stabilized. In addition, it is preferable that the mass ratio of niobium oxide and aluminum oxide is 50/50 to 90/10 from the viewpoint that both improvement of carrier lifetime and negative fixed charge can be achieved.

  Further, in the passivation film 107, the total content of niobium oxide and aluminum oxide is preferably 80% by mass or more, and more preferably 90% by mass or more.

  Next, the first electrode 105 which is an electrode on the light receiving surface side is formed. The first electrode 105 is formed by forming a paste mainly composed of silver (Ag) on the light-receiving surface antireflection film 103 by screen printing and performing a heat treatment (fire through). The shape of the 1st electrode 105 may be arbitrary shapes, for example, may be a known shape which consists of a finger electrode and a bus-bar electrode.

  And the 2nd electrode 106 which is an electrode of the back side is formed. The second electrode 106 can be formed by applying a paste containing aluminum as a main component using screen printing or a dispenser and heat-treating it. The shape of the second electrode 106 is preferably the same shape as the shape of the BSF layer 104, a shape covering the entire back surface, a comb shape, a lattice shape, or the like. The paste for forming the first electrode 105 and the second electrode 106, which are the electrodes on the light receiving surface side, is first printed, and then heat-treated (fire-through), whereby the first electrode 105 and the second electrode 106 are formed. The two electrodes 106 may be formed together.

  Further, by using a paste containing aluminum (Al) as a main component for forming the second electrode 106, aluminum diffuses as a dopant, and the BSF layer 104 is formed in a contact portion between the second electrode 106 and the silicon substrate 101 in a self-alignment manner. Is formed. As described above, the BSF layer 104 may be separately formed by applying a coating-type doping material solution containing boron, aluminum, or the like to the back side of the silicon substrate 101 and heat-treating it. .

  In the above description, a structural example and a manufacturing method example in which p-type silicon is used for the silicon substrate 101 are shown, but an n-type silicon substrate can also be used as the silicon substrate 101. In this case, the diffusion layer 102 is formed by a layer doped with a group III element such as boron, and the BSF layer 104 is formed by doping a group V element such as phosphorus. However, it should be noted that in this case, a leakage current flows through a portion where the inversion layer formed at the interface due to the negative fixed charge and the metal on the back surface are in contact with each other, and the conversion efficiency may be difficult to increase.

  When an n-type silicon substrate is used, a passivation film 107 containing niobium oxide and aluminum oxide can be used on the light receiving surface side as shown in FIG. FIG. 9 is a cross-sectional view illustrating a configuration example of a solar cell element using the light-receiving surface passivation film of the present embodiment.

  In this case, the diffusion layer 102 on the light receiving surface side is p-type doped with boron, and collects holes of the generated carriers on the light receiving surface side and electrons on the back surface side. For this reason, it is preferable that the passivation film 107 having a negative fixed charge is on the light receiving surface side.

  On the passivation film containing niobium oxide and aluminum oxide, an antireflection film made of SiN or the like may be further formed by CVD or the like.

  Hereafter, it demonstrates in detail, referring the reference Example and reference comparative example of this Embodiment.

[Reference Example 1-1]
3.0 g of a commercially available organometallic decomposition coating type material [High Purity Chemical Laboratory, Ltd. SYM-AL04, concentration 2.3 mass%] from which aluminum oxide (Al ₂ O ₃ ) can be obtained by heat treatment (firing), and heat treatment A commercially available organometallic decomposition coating-type material [High Purity Chemical Laboratory Nb-05, concentration 5% by mass] from which niobium oxide (Nb ₂ O ₅ ) is obtained by (baking) is mixed with 3.0 g, A passivation material (a-1) which is a coating type material was prepared.

The passivation material (a-1) was spin-coated on one side of a 725 μm-thick 8-inch p-type silicon substrate (8 Ωcm to 12 Ωcm) from which a natural oxide film was previously removed with hydrofluoric acid having a concentration of 0.049% by mass. Pre-baking was performed on the plate at 120 ° C. for 3 minutes. Thereafter, a heat treatment (firing) was performed at 650 ° C. for 1 hour in a nitrogen atmosphere to obtain a passivation film containing nitric oxide and niobium oxide [niobium oxide / aluminum oxide = 68/32 (mass ratio)]. It was 43 nm when the film thickness was measured with the ellipsometer. When the FT-IR of the passivation film was measured, a peak due to a very few alkyl groups was observed in the vicinity of 1200 cm ⁻¹ .

Next, a plurality of aluminum electrodes having a diameter of 1 mm were formed by vapor deposition on the passivation film through a metal mask, and a capacitor having a MIS (Metal-Insulator-Semiconductor) structure was produced. . The voltage dependence (CV characteristics) of the capacitance of this capacitor was measured with a commercially available prober and LCR meter (HP, 4275A). As a result, it was found that the flat band voltage (Vfb) shifted from an ideal value of −0.81 V to +0.32 V. From this shift amount, it was found that the passivation film obtained from the passivation material (a-1) showed a negative fixed charge with a fixed charge density (Nf) of −7.4 × 10 ¹¹ cm ⁻² .

  In the same manner as described above, the passivation material (a-1) is applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to heat treatment (baking) at 650 ° C. for 1 hour in a nitrogen atmosphere. A sample in which both surfaces of the substrate were covered with a passivation film was produced. The carrier lifetime of this sample was measured by a lifetime measuring device (Kobelco Research Institute, RTA-540). As a result, the carrier lifetime was 530 μs. For comparison, the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 μs.

  From the above, it was found that the passivation film obtained by heat-treating (sintering) the passivation material (a-1) exhibits a certain degree of passivation performance and a negative fixed charge.

[Reference Example 1-2]
As in Reference Example 1-1, a commercially available organometallic decomposition coating material from which aluminum oxide (Al ₂ O ₃ ) can be obtained by heat treatment (firing) [High Purity Chemical Laboratory, SYM-AL04, concentration 2. 3 mass%] and a commercially available organometallic decomposable coating material from which niobium oxide (Nb ₂ O ₅ ) is obtained by heat treatment (firing) [High Purity Chemical Laboratory, Nb-05, concentration 5 mass%] Then, the materials were mixed at different ratios to prepare passivation materials (a-2) to (a-7) shown in Table 2.

  Similarly to Reference Example 1-1, each of the passivation materials (a-2) to (a-7) was applied to one side of a p-type silicon substrate, and heat treatment (firing) was performed to produce a passivation film. The voltage dependence of the capacitance of the obtained passivation film was measured, and the fixed charge density was calculated therefrom.

  Further, in the same manner as in Reference Example 1-1, the carrier lifetime was measured using a sample obtained by applying a passivation material to both sides of a p-type silicon substrate and performing heat treatment (firing). The results obtained are summarized in Table 2.

Although the results are different depending on the ratio (mass ratio) of niobium oxide / aluminum oxide after heat treatment (firing), the passivation materials (a-2) to (a-7) also have a carrier lifetime after heat treatment (firing). Since it showed a certain value, it was suggested that it functions as a passivation film. It can be seen that the passivation films obtained from the passivation materials (a-2) to (a-7) all stably show negative fixed charges and can be suitably used as a passivation film for a p-type silicon substrate. It was.

[Reference Example 1-3]
3.18 g (0.010 mol) of commercially available niobium (V) ethoxide (structural formula: Nb (OC ₂ H ₅ ) ₅ , molecular weight: 318.21) and commercially available aluminum triisopropoxide (structural formula: Al ( A passivation material (c-1) having a concentration of 5% by mass was prepared by dissolving 1.02 g (0.005 mol) of OCH (CH ₃ ) ₂ ) ₃ , molecular weight: 204.25) in 80 g of cyclohexane.

The passivation material (c-1) is spin-coated on one side of a 725 μm-thick 8-inch p-type silicon substrate (8 Ωcm to 12 Ωcm) from which a natural oxide film has been previously removed with hydrofluoric acid having a concentration of 0.049% by mass. Pre-baking was performed at 120 ° C. for 3 minutes on the plate. Thereafter, heat treatment (baking) was performed at 600 ° C. for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and niobium oxide. When the film thickness was measured with an ellipsometer, it was 50 nm. As a result of elemental analysis, it was found that Nb / Al / C = 81/14/5 (mass%). When the FT-IR of the passivation film was measured, a peak due to a very few alkyl groups was observed in the vicinity of 1200 cm ⁻¹ .

Next, a plurality of aluminum electrodes having a diameter of 1 mm were formed by vapor deposition on the passivation film through a metal mask, and a capacitor having a MIS (Metal-Insulator-Semiconductor) structure was produced. . The voltage dependence (CV characteristics) of the capacitance of this capacitor was measured with a commercially available prober and LCR meter (HP, 4275A). As a result, it was found that the flat band voltage (Vfb) was shifted from an ideal value of −0.81 V to +4.7 V. From this shift amount, it was found that the passivation film obtained from the passivation material (c-1) had a fixed charge density (Nf) of −3.2 × 10 ¹² cm ⁻² and a negative fixed charge.

  In the same manner as above, the passivation material (c-1) is applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to heat treatment (baking) at 600 ° C. for 1 hour in a nitrogen atmosphere to obtain silicon. A sample in which both surfaces of the substrate were covered with a passivation film was produced. The carrier lifetime of this sample was measured by a lifetime measuring device (Kobelco Research Institute, RTA-540). As a result, the carrier lifetime was 330 μs. For comparison, the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 μs.

  From the above, it was found that the passivation film obtained by heat-treating (sintering) the passivation material (c-1) showed a certain degree of passivation performance and a negative fixed charge.

[Reference Example 1-4]
2.35 g (0.0075 mol) of commercially available niobium (V) ethoxide (structural formula: Nb (OC ₂ H ₅ ) ₅ , molecular weight: 318.21) and commercially available aluminum triisopropoxide (structural formula: Al ( 1.02 g (0.005 mol) of OCH (CH ₃ ) ₂ ) ₃ , molecular weight: 204.25) and 10 g of novolac resin were dissolved in 10 g of diethylene glycol monobutyl ether acetate and 10 g of cyclohexane to obtain a passivation material (c -2) was prepared.

The passivation material (c-2) is spin-coated on one side of a 725 μm-thick 8-inch p-type silicon substrate (8 Ωcm to 12 Ωcm) from which a natural oxide film has been removed in advance with a hydrofluoric acid having a concentration of 0.049% by mass. Pre-baking was performed at 120 ° C. for 3 minutes on the plate. Thereafter, heat treatment (baking) was performed at 600 ° C. for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and niobium oxide. When the film thickness was measured by an ellipsometer, it was 14 nm. As a result of elemental analysis, it was found that Nb / Al / C = 75/17/8 (mass%). When the FT-IR of the passivation film was measured, a peak due to a very few alkyl groups was observed in the vicinity of 1200 cm ⁻¹ .

Next, a plurality of 1 mm diameter aluminum electrodes are deposited on the passivation film through a metal mask to form a MIS (Metal-Insulator-Semiconductor) capacitor. did. The voltage dependence (CV characteristics) of the capacitance of this capacitor was measured with a commercially available prober and LCR meter (HP, 4275A). As a result, it was found that the flat band voltage (Vfb) shifted from an ideal value of −0.81 V to +0.10 V. From this shift amount, it was found that the passivation film obtained from the passivation material (c-2) showed a negative fixed charge with a fixed charge density (Nf) of −0.8 × 10 ¹¹ cm ⁻² .

In the same manner as described above, the passivation material (c-2) is applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to heat treatment (firing) at 600 ° C. for 1 hour in a nitrogen atmosphere to obtain silicon. A sample in which both surfaces of the substrate were covered with a passivation film was produced. The carrier lifetime of this sample was measured by a lifetime measuring device (Kobelco Research Institute , RTA-540). As a result, the carrier lifetime was 200 μs. For comparison, the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 μs.

  From the above, it was found that the passivation film obtained from the passivation material (c-2) exhibited a certain degree of passivation performance and a negative fixed charge.

[Reference Example 1-5 and Reference Comparative Example 1-1]
As in Reference Example 1-1, a commercially available organometallic decomposition coating material from which aluminum oxide (Al ₂ O ₃ ) can be obtained by heat treatment (calcination) [SYM-AL04, Purity Chemical Laboratory Co., Ltd., concentration 2.3]. % By mass] and a commercially available organometallic decomposable coating type material [High Purity Chemical Laboratory Nb-05, concentration 5% by mass] from which niobium oxide (Nb ₂ O ₅ ) can be obtained by heat treatment (firing) The material was changed and mixed to prepare passivation materials (b-1) to (b-7) shown in Table 3.

  As in Reference Example 1-1, each of the passivation materials (b-1) to (b-7) was applied to one side of a p-type silicon substrate, and heat treatment (firing) was performed to produce a passivation film. Using this, the voltage dependence of the capacitance was measured, and the fixed charge density was calculated therefrom.

  Furthermore, as in Reference Example 1-1, a carrier material was measured using a sample obtained by applying a passivation material (coating material) to both sides of a p-type silicon substrate and curing it. The results obtained are summarized in Table 3.

It was found that the passivation film obtained from the passivation materials (b-1) to (b-6) has a large carrier lifetime and has a function as a passivation. In addition, when the niobium oxide / aluminum oxide ratios were 10/90 and 20/80, the fixed charge density values varied greatly, and a negative fixed charge density could not be stably obtained. It was confirmed that a negative fixed charge density can be realized by using niobium oxide. When measured by the CV method using passivation materials with niobium oxide / aluminum oxide of 10/90 and 20/80, a negative fixed charge is stably generated because a passivation film showing a positive fixed charge is obtained in some cases. It turns out that it has not reached to show. Note that a passivation film exhibiting a fixed charge can be used as a passivation film for an n-type silicon substrate.
On the other hand, a negative fixed charge density could not be obtained with the passivation material (b-7) containing 100% by mass of aluminum oxide.

[Reference Comparative Example 1-2]
Commercially available organometallic decomposable coating material that can obtain titanium oxide (TiO ₂ ) by heat treatment (firing) as the passivation material (d-1) [High-Purity Chemical Laboratory Co., Ltd. Ti-03-P, concentration 3 mass%] As a passivation material (d-2), a commercially available organometallic decomposition coating type material [High Purity Chemical Research Institute BT-06, concentration 6 mass%] from which barium titanate (BaTiO ₃ ) is obtained by heat treatment (firing) As a passivation material (d-3), a commercially available organometallic decomposition coating material [High-Purity Chemical Laboratory Co., Ltd., Hf-05, concentration 5 mass%] from which hafnium oxide (HfO ₂ ) is obtained by heat treatment (firing) is used. Got ready.

  As in Reference Example 1-1, each of the passivation materials (d-1) to (d-3) is applied to one side of a p-type silicon substrate, and then heat-treated (fired) to produce a passivation film. Using this, the voltage dependence of the capacitance was measured, and the fixed charge density was calculated therefrom.

  Further, as in Reference Example 1-1, a passivation material was applied to both sides of a p-type silicon substrate, and a carrier lifetime was measured using a sample obtained by heat treatment (firing). The results obtained are summarized in Table 4.

  It was found that the passivation film obtained from the passivation materials (d-1) to (d-3) has a small carrier lifetime and an insufficient function as a passivation. It also showed a positive fixed charge. The passivation film obtained from the passivation material (d-3) had a negative fixed charge, but its value was small. It was also found that the carrier lifetime was relatively small and the function as a passivation was insufficient.

[Reference Example 1-6]
Using a single crystal silicon substrate doped with boron as the silicon substrate 101, a solar cell element having the structure shown in FIG. 7 was manufactured. After the surface of the silicon substrate 101 was textured, a coating type phosphorous diffusion material was applied to the light receiving surface side, and a diffusion layer 102 (phosphorus diffusion layer) was formed by heat treatment. Thereafter, the coating type phosphorus diffusing material was removed with dilute hydrofluoric acid.

Next, an SiN film produced by plasma CVD was formed as the light-receiving surface antireflection film 103 on the light-receiving surface side. Thereafter, the passivation material (a-1) prepared in Reference Example 1-1 was applied to the region excluding the contact region (opening OA) on the back surface side of the silicon substrate 101 by an inkjet method. Thereafter, heat treatment was performed to form a passivation film 107 having an opening OA.
In addition, a sample using the passivation material (c-1) prepared in Reference Example 1-3 was separately prepared as the passivation film 107.

  Next, on the light-receiving surface antireflection film 103 (SiN film) formed on the light-receiving surface side of the silicon substrate 101, a paste mainly composed of silver was screen-printed in the shape of predetermined finger electrodes and bus bar electrodes. On the back side, a paste mainly composed of aluminum was screen-printed on the entire surface. Thereafter, heat treatment (fire-through) is performed at 850 ° C. to form electrodes (first electrode 105 and second electrode 106), and aluminum is diffused into the opening OA on the back surface to form the BSF layer 104. Thus, a solar cell element having the structure shown in FIG. 7 was formed.

  In this case, regarding the silver electrode on the light receiving surface, the fire-through process in which the SiN film is not perforated is described, but the opening OA is first formed in the SiN film by etching or the like, and then the silver electrode is formed. You can also.

For comparison, the passivation film 107 is not formed in the above manufacturing process, aluminum paste is printed on the entire back surface, and the p ⁺ layer 114 corresponding to the BSF layer 104 and the electrode 116 corresponding to the second electrode. Was formed on the entire surface to form a solar cell element having the structure shown in FIG. About these solar cell elements, characteristic evaluation (a short circuit current, an open circuit voltage, a fill factor, and conversion efficiency) was performed. Characteristic evaluation was measured based on JIS-C-8913 (2005) and JIS-C-8914 (2005). The results are shown in Table 5.

  From Table 5, the solar cell element having the passivation film 107 including the niobium oxide and aluminum oxide layers has both increased short-circuit current and open-circuit voltage as compared with the solar cell element not having the passivation film 107, and the conversion efficiency ( It was found that the photoelectric conversion efficiency was improved by 1% at the maximum.

<Reference Embodiment 2>
The following are the passivation film, coating material, solar cell element, and silicon substrate with passivation film according to Reference Embodiment 2.

  <1> A passivation film for use in a solar cell element having a silicon substrate, comprising aluminum oxide and at least one oxide of vanadium group element selected from the group consisting of vanadium oxide and tantalum oxide.

  <2> The passivation film according to <1>, wherein a mass ratio of the vanadium group element oxide to the aluminum oxide (vanadium group element oxide / aluminum oxide) is 30/70 to 90/10.

  <3> The passivation film according to <1> or <2>, in which a total content of the oxide of the vanadium group element and the aluminum oxide is 90% or more.

  <4> The oxide of the vanadium group element includes any of oxides of two or three vanadium group elements selected from the group consisting of vanadium oxide, niobium oxide, and tantalum oxide. Any of <1> to <3> The passivation film according to claim 1.

  <5> Heat treatment of a coating-type material comprising: a precursor of aluminum oxide; and a precursor of an oxide of at least one vanadium group element selected from the group consisting of a precursor of vanadium oxide and a precursor of tantalum oxide. The passivation film according to any one of <1> to <4>, which is a product.

  <6> an aluminum oxide precursor, and at least one vanadium group element oxide precursor selected from the group consisting of a vanadium oxide precursor and a tantalum oxide precursor, and having a silicon substrate A coating type material used for forming a passivation film of a solar cell element.

<7> a p-type silicon substrate;
An n-type impurity diffusion layer formed on the first surface side which is the light-receiving surface side of the silicon substrate;
A first electrode formed on the impurity diffusion layer;
A passivation film formed on the second surface side opposite to the light receiving surface side of the silicon substrate and having an opening;
A second electrode formed on the second surface side of the silicon substrate and electrically connected to the second surface side of the silicon substrate through the opening of the passivation film;
The said passivation film is a solar cell element containing aluminum oxide and the oxide of the at least 1 sort (s) of vanadium group element selected from the group which consists of vanadium oxide and a tantalum oxide.

<8> A p-type impurity diffusion layer formed on part or all of the second surface side of the silicon substrate and doped with an impurity at a higher concentration than the silicon substrate,
The solar cell element according to <7>, wherein the second electrode is electrically connected to the p-type impurity diffusion layer through an opening of the passivation film.

<9> an n-type silicon substrate;
A p-type impurity diffusion layer formed on the first surface which is the light-receiving surface side of the silicon substrate;
A first electrode formed on the impurity diffusion layer;
A passivation film formed on the second surface side opposite to the light receiving surface side of the silicon substrate and having an opening;
A second electrode formed on the second surface side of the silicon substrate and electrically connected to the second surface side of the silicon substrate through the opening of the passivation film;
The said passivation film is a solar cell element containing aluminum oxide and the oxide of the at least 1 sort (s) of vanadium group element selected from the group which consists of vanadium oxide and a tantalum oxide.

<10> An n-type impurity diffusion layer formed on a part or all of the second surface side of the silicon substrate and doped with impurities at a higher concentration than the silicon substrate,
The solar cell element according to <9>, wherein the second electrode is electrically connected to the n-type impurity diffusion layer through an opening of the passivation film.

  <11> The solar cell element according to any one of <7> to <10>, wherein a mass ratio of the oxide of the vanadium group element and the aluminum oxide in the passivation film is 30/70 to 90/10. .

  <12> The solar cell element according to any one of <7> to <11>, wherein a total content of the oxide of the vanadium group element and the aluminum oxide in the passivation film is 90% or more.

  <13> The oxide of the vanadium group element includes oxides of two or three vanadium group elements selected from the group consisting of vanadium oxide, niobium oxide, and tantalum oxide, <7> to <12> The solar cell element according to any one of the above.

<14> a silicon substrate;
The passivation film for solar cell elements according to any one of <1> to <5>, provided on the entire surface or a part of the silicon substrate,
A silicon substrate with a passivation film.

  According to the reference embodiment described above, a passivation film having a long silicon carrier lifetime and a negative fixed charge can be realized at a low cost. In addition, a coating type material for realizing the formation of the passivation film can be provided. In addition, a low-cost and highly efficient solar cell element using the passivation film can be realized. In addition, a silicon substrate with a passivation film having a long carrier lifetime and a negative fixed charge can be realized at low cost.

  The passivation film of the present embodiment is a passivation film used for a silicon solar cell element, and includes aluminum oxide and an oxide of at least one vanadium group element selected from the group consisting of vanadium oxide and tantalum oxide. It is what was included.

  In this embodiment mode, the amount of fixed charges included in the passivation film can be controlled by changing the composition of the passivation film. Here, the vanadium group element is a Group 5 element in the periodic table, and is an element selected from vanadium, niobium, and tantalum.

  The mass ratio of the vanadium group element oxide to aluminum oxide is more preferably 35/65 to 90/10, from the viewpoint that the negative fixed charge can be stabilized, and is 50/50 to 90/10. More preferably.

  The mass ratio of vanadium group element oxide and aluminum oxide in the passivation film is determined by energy dispersive X-ray spectroscopy (EDX), secondary ion mass spectrometry (SIMS), and high frequency inductively coupled plasma mass spectrometry (ICP-MS). ) Can be measured. Specific measurement conditions are as follows in the case of ICP-MS, for example. Dissolving the passivation film in acid or alkaline aqueous solution, atomizing this solution and introducing it into Ar plasma, measuring the wavelength and intensity by spectroscopically analyzing the light emitted when the excited element returns to the ground state, Element qualification is performed from the obtained wavelength, and quantification is performed from the obtained intensity.

  The total content of vanadium group oxide and aluminum oxide in the passivation film is preferably 80% by mass or more, and more preferably 90% by mass or more from the viewpoint of maintaining good characteristics. When the components other than the oxide of vanadium group elements and aluminum oxide in the passivation film increase, the effect of negative fixed charges increases.

  Further, in the passivation film, components other than the oxide of vanadium group element and aluminum oxide may be contained as an organic component from the viewpoint of improving the film quality and adjusting the elastic modulus. The presence of the organic component in the passivation film can be confirmed by elemental analysis and measurement of the FT-IR of the film.

As the oxide of the vanadium group element, it is preferable to select vanadium oxide (V ₂ O ₅ ) from the viewpoint of obtaining a larger negative fixed charge.

  The passivation film may include an oxide of a vanadium group element selected from the group consisting of vanadium oxide, niobium oxide, and tantalum oxide as an oxide of a vanadium group element.

  The passivation film is preferably obtained by heat-treating a coating-type material, and can be obtained by forming a coating-type material using a coating method or a printing method, and then removing organic components by heat treatment. More preferred. That is, the passivation film may be obtained as a heat-treated product of a coating type material containing an aluminum oxide precursor and a vanadium group element oxide precursor. Details of the coating material will be described later.

The coating type material of the present embodiment is a coating type material used for a passivation film for a solar cell element having a silicon substrate, and includes a precursor of aluminum oxide, a precursor of vanadium oxide, and a precursor of tantalum oxide. And a precursor of an oxide of at least one vanadium group element selected from the group. As a precursor of the oxide of the vanadium group element contained in the coating material, a precursor of vanadium oxide (V ₂ O ₅ ) is selected from the viewpoint of the negative fixed charge of the passivation film formed from the coating material. It is preferable. The coating type material is composed of two or three vanadium group elements selected from the group consisting of vanadium oxide precursors, niobium oxide precursors and tantalum oxide precursors as vanadium group oxide precursors. An oxide precursor may also be included.

The aluminum oxide precursor can be used without particular limitation as long as it produces aluminum oxide. As the aluminum oxide precursor, it is preferable to use an organic aluminum oxide precursor from the viewpoint of uniformly dispersing aluminum oxide on the silicon substrate and a chemically stable viewpoint. Examples of the organic aluminum oxide precursor include aluminum triisopropoxide (structural formula: Al (OCH (CH ₃ ) ₂ ) ₃ , Kojundo Chemical Laboratory, SYM-AL04.

  The precursor of the oxide of the vanadium group element can be used without particular limitation as long as it generates an oxide of the vanadium group element. The vanadium group element oxide precursor is preferably an organic vanadium group oxide oxide precursor from the viewpoint of uniformly dispersing aluminum oxide on the silicon substrate and chemically stable. .

Examples of organic vanadium oxide precursors include vanadium (V) oxytriethoxide (structural formula: VO (OC ₂ H ₅ ) ₃ , molecular weight: 202.13), High Purity Chemical Laboratory, V-02 can be mentioned. Examples of organic tantalum oxide precursors include tantalum (V) methoxide (structural formula: Ta (OCH ₃ ) ₅ , molecular weight: 336.12), Kojundo Chemical Laboratory, Ta-10-P Can be mentioned. Examples of organic niobium oxide precursors include niobium (V) ethoxide (structural formula: Nb (OC ₂ H ₅ ) ₅ , molecular weight: 318.21), High Purity Chemical Laboratory, Nb-05. Can be mentioned.

  By forming a coating type material containing an organic vanadium group oxide precursor and an organic aluminum oxide precursor using a coating method or a printing method, and then removing the organic components by a heat treatment, A passivation film can be obtained. Therefore, as a result, a passivation film containing an organic component may be used. The content of the organic component in the passivation film is more preferably less than 10% by mass, still more preferably 5% by mass or less, and particularly preferably 1% by mass or less.

  The solar cell element (photoelectric conversion device) of the present embodiment includes the passivation film (insulating film, protective insulating film) described in the above embodiment in the vicinity of the photoelectric conversion interface of the silicon substrate, that is, aluminum oxide and vanadium oxide. And at least one oxide of a vanadium group element selected from the group consisting of tantalum oxide. By containing aluminum oxide and an oxide of at least one vanadium group element selected from the group consisting of vanadium oxide and tantalum oxide, the carrier lifetime of the silicon substrate can be extended and negative fixed charges can be obtained. And the characteristics (photoelectric conversion efficiency) of the solar cell element can be improved.

  For the description of the structure and the manufacturing method of the solar cell element according to the present embodiment, the description of the structure and the manufacturing method of the solar cell element according to Reference Embodiment 1 can be referred to.

  Hereafter, it demonstrates in detail, referring the reference Example and reference comparative example of this Embodiment.

<When vanadium oxide is used as the oxide of vanadium group element>
[Reference Example 2-1]
3.0 g of a commercially available organometallic thin film coating type material [High purity chemical research laboratory, SYM-AL04, concentration 2.3 mass%] from which aluminum oxide (Al ₂ O ₃ ) can be obtained by heat treatment (firing) And 6.0 g of a commercially available organometallic thin film coating material [Vitamin Purity Laboratory, V-02, concentration 2 mass%] from which vanadium oxide (V ₂ O ₅ ) can be obtained by heat treatment (firing). By mixing, a passivation material (a2-1) which is a coating type material was prepared.

Passivation of passivation material (a2-1) to one side of a 725 μm thick 8-inch p-type silicon substrate (8 Ω · cm to 12 Ω · cm) with natural oxide film removed beforehand with hydrofluoric acid at a concentration of 0.49% by mass It was applied and placed on a hot plate and prebaked at 120 ° C. for 3 minutes. Thereafter, a heat treatment (firing) was performed at 700 ° C. for 30 minutes in a nitrogen atmosphere to obtain a passivation film containing vanadium oxide and vanadium oxide [vanadium oxide / aluminum oxide = 63/37 (mass%)]. It was 51 nm when the film thickness was measured with the ellipsometer. When the FT-IR of the passivation film was measured, a peak due to a very few alkyl groups was observed in the vicinity of 1200 cm ⁻¹ .

Next, a plurality of aluminum electrodes having a diameter of 1 mm were formed on the above-described passivation film by vapor deposition through a metal mask, thereby manufacturing a capacitor having a MIS (metal-insulator-semiconductor) structure. . The voltage dependence (CV characteristics) of the capacitance of this capacitor was measured with a commercially available prober and LCR meter (HP, 4275A). As a result, it was found that the flat band voltage (Vfb) shifted from an ideal value of −0.81 V to +0.02 V. From this shift amount, it was found that the passivation film obtained from the passivation material (a2-1) showed a negative fixed charge with a fixed charge density (Nf) of −5.2 × 10 ¹¹ cm ⁻² .

  In the same manner as described above, the passivation material (a2-1) was applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to heat treatment (baking) at 650 ° C. for 1 hour in a nitrogen atmosphere. A sample in which both surfaces of the substrate were covered with a passivation film was produced. The carrier lifetime of this sample was measured with a lifetime measuring device (Kobelco Research Institute, RTA-540). As a result, the carrier lifetime was 400 μs. For comparison, the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 μs. Further, when the carrier lifetime was measured again 14 days after the preparation of the sample, the carrier lifetime was 380 μs. Thereby, it was found that the decrease in carrier lifetime (from 400 μs to 380 μs) was within −10%, and the decrease in carrier lifetime was small.

  From the above, it was found that the passivation film obtained by heat-treating (sintering) the passivation material (a2-1) exhibits a certain degree of passivation performance and a negative fixed charge.

[Reference Example 2-2]
Similar to Reference Example 2-1, a commercially available organometallic thin film coated material from which aluminum oxide (Al ₂ O ₃ ) can be obtained by heat treatment (firing) [High Purity Chemical Laboratory, SYM-AL04, concentration 2 .3 mass%] and a commercially available organic metal thin film coating type material [Vitamin Purity Laboratory, V-02, concentration 2 mass%] from which vanadium oxide (V ₂ O ₅ ) is obtained by heat treatment, Passivation materials (a2-2) to (a2-7) shown in Table 6 were prepared by changing the ratio.

  As in Reference Example 2-1, each of the passivation materials (a2-2) to (a2-7) was applied to one side of a p-type silicon substrate, and heat treatment (firing) was performed to produce a passivation film. The voltage dependence of the capacitance of the obtained passivation film was measured, and the fixed charge density was calculated therefrom.

  Further, in the same manner as in Reference Example 2-1, the carrier lifetime was measured using a sample obtained by applying a passivation material to both surfaces of a p-type silicon substrate and performing heat treatment (firing).

  The results obtained are summarized in Table 6. Further, when the carrier lifetime was measured again 14 days after the preparation of the sample, the decrease in the carrier lifetime was found in any of the passivation films using the passivation materials (a2-2) to (a2-7) shown in Table 6. It was within -10%, and it was found that the decrease in carrier lifetime was small.

Although the results are different depending on the ratio (mass ratio) of vanadium oxide / aluminum oxide after heat treatment (firing), the passivation materials (a2-2) to (a2-7) are all negative after heat treatment (firing). Since it showed a fixed charge and a certain carrier lifetime, it was suggested that it functions as a passivation film. It can be seen that the passivation films obtained from the passivation materials (a2-2) to (a2-7) all stably show negative fixed charges and can be suitably used as a passivation film for a p-type silicon substrate. It was.

[Reference Example 2-3]
As a compound for obtaining vanadium oxide (V ₂ O ₅ ) by heat treatment (firing), commercially available vanadium (V) oxytriethoxide (structural formula: VO (OC ₂ H ₅ ) ₃ , molecular weight: 202.13) is 1 0.02 g (0.010 mol) and a compound obtained from aluminum oxide (Al ₂ O ₃ ) by heat treatment (calcination), commercially available aluminum triisopropoxide (structure: Al (OCH (CH ₃ ) ₂ ) ₃ , A passivation material (b2-1) having a concentration of 5% by mass was prepared by dissolving 2.04 g (0.010 mol) of molecular weight: 204.25) in 60 g of cyclohexane.

Passivation of passivation material (b2-1) on one side of a 725 μm thick 8-inch p-type silicon substrate (8Ω · cm to 12Ω · cm) from which a natural oxide film was previously removed with hydrofluoric acid having a concentration of 0.49% by mass This was applied and prebaked at 120 ° C. for 3 minutes on a hot plate. Thereafter, a heat treatment (firing) was performed at 650 ° C. for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and vanadium oxide. When the film thickness was measured with an ellipsometer, it was 60 nm. As a result of elemental analysis, it was found that V / Al / C = 64/33/3 (mass%). When the FT-IR of the passivation film was measured, a peak due to a very few alkyl groups was observed in the vicinity of 1200 cm ⁻¹ .

Next, a plurality of aluminum electrodes having a diameter of 1 mm were formed on the above-described passivation film by vapor deposition through a metal mask, thereby manufacturing a capacitor having a MIS (metal-insulator-semiconductor) structure. . The voltage dependence (CV characteristics) of the capacitance of this capacitor was measured with a commercially available prober and LCR meter (HP, 4275A). As a result, it was found that the flat band voltage (Vfb) shifted from an ideal value of −0.81 V to +0.10 V. From this shift amount, it was found that the passivation film obtained from the passivation material (b2-1) showed a negative fixed charge with a fixed charge density (Nf) of −6.2 × 10 ¹¹ cm ⁻² .

  In the same manner as described above, the passivation material (b2-1) was applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to heat treatment (baking) at 600 ° C. for 1 hour in a nitrogen atmosphere. A sample in which both surfaces of the substrate were covered with a passivation film was produced. The carrier lifetime of this sample was measured by a lifetime measuring device (Kobelco Research Institute, RTA-540). As a result, the carrier lifetime was 400 μs. For comparison, the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 μs.

  From the above, it was found that the passivation film obtained by heat-treating (sintering) the passivation material (b2-1) exhibited a certain degree of passivation performance and a negative fixed charge.

[Reference Example 2-4]
1.52 g (0.0075 mol) of commercially available vanadium (V) oxytriethoxide (structural formula: VO (OC ₂ H ₅ ) ₃ , molecular weight: 202.13) and commercially available aluminum triisopropoxide (structural formula : Al (OCH (CH ₃ ) ₂ ) ₃ , molecular weight: 204.25), 1.02 g (0.005 mol) and 10 g of novolak resin were dissolved in 10 g of diethylene glycol monobutyl ether acetate and 10 g of cyclohexane to passivate. Material (b2-2) was prepared.

Passivation of passivation material (b2-2) on one side of a 725 μm thick 8-inch p-type silicon substrate (8 Ω · cm to 12 Ω · cm) with natural oxide film removed beforehand with hydrofluoric acid at a concentration of 0.49% by mass It was applied and placed on a hot plate and prebaked at 120 ° C. for 3 minutes. Thereafter, heating was performed at 650 ° C. for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and vanadium oxide. When the film thickness was measured with an ellipsometer, it was 22 nm. As a result of elemental analysis, it was found that V / Al / C = 71/22/7 (mass%). When the FT-IR of the passivation film was measured, a peak due to a very few alkyl groups was observed in the vicinity of 1200 cm ⁻¹ .

Next, a plurality of aluminum electrodes having a diameter of 1 mm were formed on the above-described passivation film by vapor deposition through a metal mask, thereby manufacturing a capacitor having a MIS (metal-insulator-semiconductor) structure. . The voltage dependence (CV characteristics) of the capacitance of this capacitor was measured with a commercially available prober and LCR meter (HP, 4275A). As a result, it was found that the flat band voltage (Vfb) shifted from the ideal value of −0.81 V to +0.03 V. From this shift amount, it was found that the passivation film obtained from the passivation material (b2-2) had a fixed charge density (Nf) of −2.0 × 10 ¹¹ cm ⁻² and a negative fixed charge.

  In the same manner as described above, the passivation material (b2-2) is applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to heat treatment (baking) at 600 ° C. for 1 hour in a nitrogen atmosphere to obtain silicon. A sample in which both surfaces of the substrate were covered with a passivation film was produced. The carrier lifetime of this sample was measured by a lifetime measuring device (Kobelco Research Institute, RTA-540). As a result, the carrier lifetime was 170 μs. For comparison, the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 μs.

  From the above, it was found that the passivation film obtained by curing the passivation material (b2-2) exhibited a certain degree of passivation performance and a negative fixed charge.

<When tantalum oxide is used as the oxide of vanadium group element>
[Reference Example 2-5]
Commercially available organometallic thin film coating type material [High Purity Chemical Laboratory, SYM-AL04, concentration 2.3 mass%] from which aluminum oxide (Al ₂ O ₃ ) can be obtained by heat treatment (firing) and oxidation by heat treatment A commercially available organometallic thin film coating type material [Tapuro Chemical Laboratory Co., Ltd., Ta-10-P, concentration 10% by mass] from which tantalum (Ta ₂ O ₅ ) can be obtained is mixed at different ratios. The passivation materials (c2-1) to (c2-6) shown in 7 were prepared.

  Each of the passivation materials (c2-1) to (c2-6) is a 725 μm thick 8-inch p-type silicon substrate (8Ω · cm to 12Ω) from which the natural oxide film has been removed in advance with hydrofluoric acid having a concentration of 0.49% by mass. (Cm) was spin-coated on one side, placed on a hot plate, and pre-baked at 120 ° C. for 3 minutes. Thereafter, a heat treatment (firing) was performed at 700 ° C. for 30 minutes in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and tantalum oxide. Using this passivation film, the voltage dependence of the capacitance was measured, and the fixed charge density was calculated therefrom.

  Next, each of the passivation materials (c2-1) to (c2-6) was applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and heat-treated (fired) at 650 ° C. for 1 hour in a nitrogen atmosphere. ) To prepare a sample in which both surfaces of the silicon substrate were covered with a passivation film. The carrier lifetime of this sample was measured by a lifetime measuring device (Kobelco Research Institute, RTA-540).

  The results obtained are summarized in Table 7. Further, when the carrier lifetime was measured again 14 days after the preparation of the sample, the decrease in the carrier lifetime was any of the passivation films using the passivation materials (c2-1) to (c2-6) shown in Table 7. It was within -10%, and it was found that the decrease in carrier lifetime was small.

  Although the results differ depending on the ratio (mass ratio) of tantalum oxide / aluminum oxide after heat treatment (firing), the passivation materials (c2-1) to (c2-6) are all negative after heat treatment (firing). Since it showed a fixed charge and a certain carrier lifetime, it was suggested that it functions as a passivation film.

[Reference Example 2-6]
As a compound from which tantalum oxide (Ta ₂ O ₅ ) can be obtained by heat treatment (firing), 1.18 g (0.002) of commercially available tantalum (V) methoxide (structural formula: Ta (OCH ₃ ) ₅ , molecular weight: 336.12) is obtained. As a compound from which aluminum oxide (Al ₂ O ₃ ) can be obtained by heat treatment (firing), commercially available aluminum triisopropoxide (structural formula: Al (OCH (CH ₃ ) ₂ ) ₃ , molecular weight: 204.25 2.04 g (0.010 mol) was dissolved in 60 g of cyclohexane to prepare a passivation material (d2-1) having a concentration of 5% by mass.

Passivation of passivation material (d2-1) to one side of a 725 μm thick 8-inch p-type silicon substrate (8 Ω · cm to 12 Ω · cm) with natural oxide film removed beforehand with hydrofluoric acid at a concentration of 0.49% by mass It was applied and placed on a hot plate and prebaked at 120 ° C. for 3 minutes. Thereafter, heating was performed at 700 ° C. for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and tantalum oxide. When the film thickness was measured with an ellipsometer, it was 40 nm. As a result of elemental analysis, it was found that Ta / Al / C = 75/22/3 (wt%). When the FT-IR of the passivation film was measured, a peak due to a very few alkyl groups was observed in the vicinity of 1200 cm ⁻¹ .

Next, a plurality of aluminum electrodes having a diameter of 1 mm were formed on the above-described passivation film by vapor deposition through a metal mask, thereby manufacturing a capacitor having a MIS (metal-insulator-semiconductor) structure. . The voltage dependence (CV characteristics) of the capacitance of this capacitor was measured with a commercially available prober and LCR meter (HP, 4275A). As a result, it was found that the flat band voltage (Vfb) was shifted from an ideal value of −0.81 V to −0.30 V. From this shift amount, it was found that the passivation film obtained from the passivation material (d2-1) showed a negative fixed charge at a fixed charge density (Nf) of −6.2 × 10 ¹⁰ cm ⁻² .

  In the same manner as described above, the passivation material (d2-1) was applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to heat treatment (baking) at 600 ° C. for 1 hour in a nitrogen atmosphere. A sample in which both surfaces of the substrate were covered with a passivation film was produced. The carrier lifetime of this sample was measured by a lifetime measuring device (Kobelco Research Institute, RTA-540). As a result, the carrier lifetime was 610 μs. For comparison, the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 μs.

  From the above, it was found that the passivation film obtained by heat-treating the passivation material (d2-1) exhibits a certain degree of passivation performance and a negative fixed charge.

[Reference Example 2-7]
As a compound for obtaining tantalum oxide (Ta ₂ O ₅ ) by heat treatment (firing), 1.18 g (0.005 mol) of commercially available tantalum (V) methoxide (structural formula: Ta (OCH ₃ ) ₅ , molecular weight: 336.12) ) And aluminum oxide (Al ₂ O ₃ ) obtained by heat treatment (firing), a commercially available aluminum triisopropoxide (structure: Al (OCH (CH ₃ ) ₂ ) ₃ , molecular weight: 204.25) 1.02 g (0.005 mol) and 10 g of novolak resin were dissolved in a mixture of 10 g of diethylene glycol monobutyl ether acetate and 10 g of cyclohexane to prepare a passivation material (d2-2).

Passivation of passivation material (d2-2) on one side of a 725 μm thick 8-inch p-type silicon substrate (8 Ω · cm to 12 Ω · cm) with natural oxide film removed beforehand with hydrofluoric acid at a concentration of 0.49% by mass This was applied and prebaked at 120 ° C. for 3 minutes on a hot plate. Thereafter, heating was performed at 650 ° C. for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and tantalum oxide. When the film thickness was measured with an ellipsometer, it was 18 nm. As a result of elemental analysis, it was found that Ta / Al / C = 72/20/8 (wt%). When the FT-IR of the passivation film was measured, a peak due to a very few alkyl groups was observed in the vicinity of 1200 cm ⁻¹ .

Next, a plurality of aluminum electrodes having a diameter of 1 mm were formed on the above-described passivation film by vapor deposition through a metal mask, thereby manufacturing a capacitor having a MIS (metal-insulator-semiconductor) structure. . The voltage dependence (CV characteristics) of the capacitance of this capacitor was measured with a commercially available prober and LCR meter (HP, 4275A). As a result, it was found that the flat band voltage (Vfb) shifted from an ideal value of −0.81 V to −0.43 V. From this shift amount, it was found that the passivation film obtained from the passivation material (d-2) had a fixed charge density (Nf) of −5.5 × 10 ¹⁰ cm ⁻² and a negative fixed charge.

  In the same manner as above, the passivation material (d2-2) was applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to heat treatment (baking) at 600 ° C. for 1 hour in a nitrogen atmosphere. A sample in which both surfaces of the substrate were covered with a passivation film was produced. The carrier lifetime of this sample was measured by a lifetime measuring device (Kobelco Research Institute, RTA-540). As a result, the carrier lifetime was 250 μs. For comparison, the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 μs.

  From the above, it was found that the passivation film obtained by heat-treating (sintering) the passivation material (d2-2) exhibited a certain degree of passivation performance and a negative fixed charge.

<When two or more vanadium group element oxides are used>
[Reference Example 2-8]
Commercially available organometallic thin film coating type material that can obtain aluminum oxide (Al ₂ O ₃ ) by heat treatment (firing) [High Purity Chemical Laboratory, SYM-AL04, concentration 2.3 mass%], heat treatment (firing) Commercially available organometallic thin film coating type material (VCO, Co., Ltd., V-02, concentration 2% by mass) from which vanadium oxide (V ₂ O ₅ ) can be obtained by heat treatment, and tantalum oxide (Ta ₂ O ₅ ), a commercially available organometallic thin film coating material [High Purity Chemical Laboratory, Ta-10-P, concentration 10% by mass] is mixed to form a passivation material (e2) that is a coating material. -1) was prepared (see Table 8).

By commercially available organometallic thin film coating type material [Coal Chemical Industries Ltd. SYM-AL04, concentration 2.3 mass%] from which aluminum oxide (Al ₂ O ₃ ) can be obtained by heat treatment (firing), heat treatment (firing) Niobium oxide (Nb ₂ O) by commercially available organometallic thin film coating type material (Vitamin Co., Ltd., V-02, concentration 2 mass%) from which vanadium oxide (V ₂ O ₅ ) is obtained, and heat treatment (firing) ₅ ) A commercially available organometallic thin film coating type material [Co., Ltd., High Purity Chemical Laboratory Co., Ltd., Nb-05, concentration 5 mass%] is mixed to obtain a passivation material (e2-2) which is a coating type material. Prepared (see Table 8).

By commercially available organometallic thin film coating type material [Coal Chemical Industries Ltd. SYM-AL04, concentration 2.3 mass%] from which aluminum oxide (Al ₂ O ₃ ) can be obtained by heat treatment (firing), heat treatment (firing) Niobium oxide (Nb) by commercially available organometallic thin film coating material [Tapuro Chemical Laboratories Ta-10-P, concentration 10% by mass] from which tantalum oxide (Ta ₂ O ₅ ) can be obtained, and heat treatment (firing) ₂ O ₅ ), a commercially available organometallic thin film coating material [High Purity Chemical Laboratory Nb-05, concentration 5 mass%] is mixed to form a passivation material (e2-3) that is a coating material. Was prepared (see Table 8).

By commercially available organometallic thin film coating type material [Coal Chemical Industries Ltd. SYM-AL04, concentration 2.3 mass%] from which aluminum oxide (Al ₂ O ₃ ) can be obtained by heat treatment (firing), heat treatment (firing) Tantalum oxide (Ta ₂ O ₅ ) by commercially available organic metal thin film coating type material [Co., Ltd., Purity Chemical Laboratory V-02, concentration 2 mass%] from which vanadium oxide (V ₂ O ₅ ) is obtained, and heat treatment (firing) Niobium oxide (Nb ₂ O ₅ ) can be obtained by a commercially available organometallic thin film coating type material [High purity chemical research laboratory Ta-10-P, concentration 10% by mass] and heat treatment (firing). Commercially available organic metal thin film coating type material [Co., Ltd. High Purity Chemical Laboratory Nb-05, concentration 5 mass%] was mixed to prepare a passivation material (e2-4) which is a coating type material (see Table 8). ).

  Each of the passivation materials (e2-1) to (e2-4) has a thickness of 725 μm and 8 inches, in which the natural oxide film is previously removed with hydrofluoric acid having a concentration of 0.49% by mass, as in Reference Example 2-1. A p-type silicon substrate (8 Ω · cm to 12 Ω · cm) was spin-coated on one side, placed on a hot plate, and pre-baked at 120 ° C. for 3 minutes. Thereafter, a heat treatment (firing) was performed at 650 ° C. for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and two or more vanadium group element oxides.

  Using the passivation film obtained above, the voltage dependence of the capacitance was measured, and the fixed charge density was calculated therefrom.

  Next, each of the passivation materials (e2-1) to (e2-4) is applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and heat-treated (fired) at 650 ° C. for 1 hour in a nitrogen atmosphere. ) To prepare a sample in which both surfaces of the silicon substrate were covered with a passivation film. The carrier lifetime of this sample was measured by a lifetime measuring device (Kobelco Research Institute, RTA-540).

  The results obtained are summarized in Table 8.

  Passivation using passivation materials (e2-1) to (e2-4), depending on the ratio (mass ratio) of the oxide of two or more vanadium group elements and the aluminum oxide after heat treatment (firing). Regarding the films, all showed negative fixed charges after heat treatment (firing), and the carrier lifetime also showed a certain value, suggesting that it functions as a passivation film.

[Reference Example 2-9]
Similar to Reference Example 2-1, a commercially available organometallic thin film coated material from which aluminum oxide (Al ₂ O ₃ ) can be obtained by heat treatment (firing) [High Purity Chemical Laboratory, SYM-AL04, concentration 2 .3 mass%] and a commercially available organic metal thin film coating type material that can be obtained by heat treatment (firing) vanadium oxide (V ₂ O ₅ ) [High Purity Chemical Laboratory, V-02, concentration 2 mass%] Or a commercially available organic metal thin film coating type material [Tapuro Chemical Laboratory Co., Ltd., Ta-10-P, concentration 10% by mass] from which tantalum oxide (Ta ₂ O ₅ ) can be obtained by heat treatment (firing). Then, passivation materials (f2-1) to (f2-8), which are coating-type materials, were prepared (see Table 9).

  Moreover, the passivation material (f2-9) which used aluminum oxide independently was prepared (refer Table 9).

  As in Reference Example 2-1, each of the passivation materials (f2-1) to (f2-9) was applied to one side of a p-type silicon substrate, and then heat treatment (firing) was performed to form a passivation film. This was used to measure the voltage dependence of the capacitance, and the fixed charge density was calculated therefrom.

  Further, as in Reference Example 2-1, samples obtained by applying each of the passivation materials (f2-1) to (f2-9) to both sides of a p-type silicon substrate and heat-treating (firing) were obtained. Used to measure the carrier lifetime. The results obtained are summarized in Table 9.

  As shown in Table 9, when the aluminum oxide / vanadium oxide or tantalum oxide in the passivation material is 90/10 and 80/20, the fixed charge density varies greatly, and the negative fixed charge density is stable. However, it was confirmed that a negative fixed charge density can be realized by using aluminum oxide and niobium oxide. When measured by the CV method using a passivation material in which aluminum oxide / vanadium oxide or tantalum oxide is 90/10 and 80/20, a passivation film showing a positive fixed charge is obtained in some cases. It turns out that it has not reached to show stably. Note that a passivation film exhibiting a positive fixed charge can be used as a passivation film for an n-type silicon substrate. On the other hand, in the passivation material (f2-9) in which aluminum oxide is 100% by mass, a negative fixed charge density could not be obtained.

[Reference Example 2-10]
Using a single crystal silicon substrate with boron as a dopant as the silicon substrate 101, a solar cell element having the structure shown in FIG. 7 was manufactured. After the surface of the silicon substrate 101 was textured, a coating type phosphorous diffusion material was applied only to the light receiving surface side, and a diffusion layer 102 (phosphorus diffusion layer) was formed by heat treatment. Thereafter, the coating type phosphorus diffusing material was removed with dilute hydrofluoric acid.

  Next, a SiN film was formed on the light receiving surface side by plasma CVD as the light receiving surface antireflection film 103. Thereafter, the passivation material (a2-1) prepared in Reference Example 2-1 was applied to the region excluding the contact region (opening OA) on the back surface side of the silicon substrate 101 by an inkjet method. Thereafter, heat treatment was performed to form a passivation film 107 having an opening OA. In addition, a sample using the passivation material (c2-1) prepared in Reference Example 2-5 was separately prepared as the passivation film 107.

  Next, on the light-receiving surface antireflection film 103 (SiN film) formed on the light-receiving surface side of the silicon substrate 101, a paste mainly composed of silver was screen-printed in the shape of predetermined finger electrodes and bus bar electrodes. On the back side, a paste mainly composed of aluminum was screen-printed on the entire surface. Thereafter, heat treatment (fire-through) is performed at 850 ° C. to form electrodes (first electrode 105 and second electrode 106), and aluminum is diffused into the opening OA on the back surface to form the BSF layer 104. Thus, a solar cell element having the structure shown in FIG. 7 was formed.

  In this case, regarding the formation of the silver electrode on the light receiving surface, the fire-through process in which the SiN film is not perforated is described. However, the opening OA is first formed in the SiN film by etching or the like, and then the silver electrode is formed. You can also

For comparison, the passivation film 107 is not formed in the above manufacturing process, aluminum paste is printed on the entire back surface, and the p ⁺ layer 114 corresponding to the BSF layer 104 and the electrode 116 corresponding to the second electrode. Was formed on the entire surface to form a solar cell element having the structure of FIG. About these solar cell elements, characteristic evaluation (a short circuit current, an open circuit voltage, a fill factor, and conversion efficiency) was performed. Characteristic evaluation was measured based on JIS-C-8913 (2005) and JIS-C-8914 (2005). The results are shown in Table 10.

From Table 10, the solar cell element having a passivation layer 107 is different from the solar cells elements having no passivation film 107 has increased short-circuit current and open circuit voltage are both conversion efficiency (photoelectric conversion efficiency) at the maximum It was found to improve by 0.6%.

  The disclosures of Japanese Patent Application Nos. 2012-160336, 2012-218389, 2013-011934, 2013-040153, and 2013-103571 are incorporated herein by reference in their entirety. All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.

Claims (10)

A composition for forming a field effect passivation layer comprising a compound represented by the following general formula (I) and at least one selected from the group consisting of a fatty acid amide, a polyalkylene glycol compound and an organic filler.
M (OR ¹ ) _m (I)
[Wherein M includes at least one metal element selected from the group consisting of Nb, Ta, V, Y, and Hf. R ¹ each independently represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms. m represents an integer of 1 to 5. ] Furthermore, the composition for field effect type | mold passivation layer formation of Claim 1 containing the compound represented with the following general formula (II).


Wherein, R ² each independently represent an alkyl group having 1 to 8 carbon atoms. n represents an integer of 0 to 3. X ² and X ³ each independently represent an oxygen atom or a methylene group. R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. ] The field effect type passivation layer according to claim 1 or 2, comprising the polyalkylene glycol compound, wherein the polyalkylene glycol compound comprises at least one selected from compounds represented by the following general formula (III): Forming composition.

[In Formula (III), R ⁶ and R ⁷ each independently represent a hydrogen atom or an alkyl group, and R ⁸ represents an alkylene group. n is an integer of 3 or more. A plurality of R ⁸ may be the same or different. ] The fatty acid amide comprising the compound represented by the following general formula (1), the compound represented by (2), the compound represented by (3) and the compound represented by (4) The composition for forming a field effect passivation layer according to any one of claims 1 to 3, comprising at least one selected from the group consisting of:
R ⁹ CONH ₂ (1)
R ⁹ CONH-R ¹⁰ -NHCOR ⁹ (2)
R ⁹ NHCO-R ¹⁰ -CONHR ⁹ (3)
R ⁹ CONH—R ¹⁰ —N (R ¹¹ ) ₂ ... (4)
[In General Formulas (1), (2), (3) and (4), R ⁹ and R ¹¹ each independently represent an alkyl group having 1 to 30 carbon atoms or an alkenyl group having 2 to 30 carbon atoms, R ¹⁰ represents an alkylene group having 1 to ¹⁰ carbon atoms. A plurality of R ¹¹ may be the same or different. ] The field effect type according to any one of claims 1 to 4, comprising the organic filler, wherein the organic filler comprises at least one selected from the group consisting of an acrylic resin, a cellulose resin, and a polystyrene resin. A composition for forming a passivation layer. A semiconductor substrate;
A field effect passivation layer that is a heat-treated product of the field effect passivation layer forming composition according to any one of claims 1 to 5, which is provided on the entire surface or a part of the semiconductor substrate.
A semiconductor substrate with a field effect passivation layer, comprising: A step of forming a composition layer by applying the field-effect passivation layer forming composition according to any one of claims 1 to 5 to the entire surface or a part of the semiconductor substrate;
Heat-treating the composition layer to form a field effect passivation layer;
A method for manufacturing a semiconductor substrate with a field-effect passivation layer comprising: a semiconductor substrate in which a p-type layer and an n-type layer are pn-junction;
A field effect passivation layer that is a heat-treated product of the field effect passivation layer forming composition according to any one of claims 1 to 5, which is provided on the entire surface or a part of the semiconductor substrate.
An electrode disposed on one or more layers selected from the group consisting of the p-type layer and the n-type layer;
A solar cell element having a semiconductor substrate having a pn junction formed by joining a p-type layer and an n-type layer and having an electrode on one or more layers selected from the group consisting of the p-type layer and the n-type layer; A step of forming the composition layer by applying the field-effect passivation layer forming composition according to any one of claims 1 to 5 on one or both of the surfaces having:
Heat-treating the composition layer to form a field effect passivation layer;
The manufacturing method of the solar cell element which has this. A solar cell element according to claim 8,
A wiring material provided on the electrode of the solar cell element;
A solar cell having: