TW201738249A - Composition for forming passivation layer, semiconductor substrate with passivation layer, method for producing the same, solar cell element, method for producing the same, and solar cell - Google Patents

Abstract

A composition for forming a passivation layer, wherein the composition comprises: a compound represented by M(OR1)m, wherein M represents at least one selected from the group consisting of Al, Nb, Ta, VO, Y and Hf, R1 independently represents an alkyl group or an aryl group, and m represents an integer from 1 to 5; and water, wherein the composition is applied to a semiconductor substrate by a printing method and becomes a passivation layer having a thickness of 200 nm or less after thermal treatment.

Description

Composition for forming passivation layer, semiconductor substrate with passivation layer, method for producing the same, solar cell element, method for producing the same, and solar cell

The present invention relates to a composition for forming a passivation layer, a semiconductor substrate with a passivation layer, a method for producing the same, a solar cell element, a method for producing the same, and a solar cell.

The manufacturing steps of the prior 矽 solar cell element will be described. First, in order to promote the high efficiency of the optical confinement effect, a p-type germanium substrate having a texture structure is formed, followed by a mixed gas environment of phosphorus oxychloride (POCl ₃ ), nitrogen and oxygen. In the middle, the treatment was carried out at 800 ° C to 900 ° C for several tens of minutes to form an n-type diffusion layer in the same manner. In this prior method, since the diffusion of phosphorus is performed using a mixed gas, an n-type diffusion layer is formed not only on the surface but also on the side surface and the back surface. Therefore, side etching for removing the n-type diffusion layer formed on the side surface is performed. Further, it is necessary to convert the n-type diffusion layer formed on the back surface into a p ⁺ -type diffusion layer. Therefore, an aluminum paste containing aluminum powder and a binder is applied to the entire back surface, and heat-treated (calcined) to convert the n-type diffusion layer into a p ⁺ -type diffusion layer, thereby forming an aluminum electrode. Obtain an ohmic contact.

However, the aluminum electrode formed of the aluminum paste has a low electrical conductivity. In order to lower the sheet resistance, the aluminum electrode usually formed on the entire back surface must have a thickness of about 10 μm to 20 μm after heat treatment (calcination). Further, since the thermal expansion coefficient of bismuth and aluminum is greatly different, in the ruthenium substrate on which the aluminum electrode is formed, a large internal stress is generated in the ruthenium substrate during the heat treatment (calcination) and cooling, and becomes a grain boundary. Damage, growth of crystal defects and causes of warpage.

In order to solve this problem, there is a method of reducing the coating amount of the aluminum paste to reduce the thickness of the back electrode layer. However, when the coating amount of the aluminum paste is reduced, the amount of aluminum diffused from the surface of the p-type germanium semiconductor substrate is insufficient. As a result, there is a problem in that the desired back surface field (BSF) effect (the effect of improving the collection efficiency of the carrier by the presence of the p ⁺ -type diffusion layer) cannot be achieved, and thus the characteristics of the solar cell are lowered.

As described above, there has been proposed a method of partially forming a point contact between a p ⁺ -type diffusion layer and an aluminum electrode by applying an aluminum paste to a part of the surface of the substrate (see, for example, Patent Document 1). In the case of such a solar cell having a point contact structure on a surface opposite to the light receiving surface (hereinafter also referred to as "back surface"), it is necessary to suppress the recombination speed of a small number of carriers on the surface of a portion other than the aluminum electrode. A SiO ₂ film or the like is proposed as a passivation layer for the back surface used in the above case (see, for example, Patent Document 2). The passivation effect of the formation of the SiO ₂ film is an effect of reducing the surface level density which causes the recombination due to the unbonded bond of the ruthenium atoms in the surface layer portion of the back surface of the ruthenium substrate.

Further, as another method of suppressing recombination of a minority carrier, there is a method of reducing the density of a minority carrier by an electric field generated by a fixed charge in the passivation layer. Such a passivation effect is generally referred to as an electric field effect, and an aluminum oxide (Al ₂ O ₃ ) film or the like is proposed as a material having a negative fixed charge (for example, refer to Patent Document 3). Such a passivation layer is usually formed by a method such as an atomic layer deposition (ALD) method or a chemical vapor deposition (CVD) method (see, for example, Non-Patent Document 1). In addition, a method using a sol-gel method as a simple method for forming an aluminum oxide film on a semiconductor substrate has been proposed (for example, refer to Non-Patent Document 2 and Non-Patent Document 3). [Prior Art Document] [Patent Literature]

[Patent Document 1] Japanese Patent No. 3107287 [Patent Document 2] Japanese Patent Laid-Open Publication No. 2004-6565 [Patent Document 3] Japanese Patent No. 4767110 [Non-Patent Document]

[Non-Patent Document 1] "Journal of Applied Physics", 104 (2008), 113703-1 to 113703-7 [Non-Patent Document 2] "Thin Solid Films", 517 (2009) ), 6327-6330 [Non-Patent Document 3] "Chinese Physics Letters", 26 (2009), 088102-1 to 088102-4

[Problems to be Solved by the Invention] The method described in Non-Patent Document 1 includes complicated manufacturing steps such as vapor deposition, and thus it may be difficult to improve productivity. In addition, since the composition for forming a passivation layer used in the methods described in Non-Patent Document 2 and Non-Patent Document 3 includes a spin coating method in the production step, it may be difficult to form a target pattern in a small number of steps.

An embodiment of the present invention has been made in view of the above-described prior art, and an object of the present invention is to provide a passivation layer-forming composition which can form a passivation layer which is excellent in film quality, excellent in pattern formation property, and excellent in passivation effect by a simple method. . Moreover, an object of an embodiment of the present invention is to provide a semiconductor substrate with a passivation layer having a passivation layer having excellent film quality and excellent pattern formation property, a method for producing the same, and a solar cell having excellent conversion efficiency. A component and a method of manufacturing the same, and a solar cell having excellent conversion efficiency. [Means for solving the problem]

The specific means for achieving the problem are as follows. <1> A composition for forming a passivation layer, comprising a compound represented by the following formula (I) and water, and applied to a semiconductor substrate by a printing method to form a passivation having an average thickness of 200 nm or less after heat treatment. Floor. M(OR ¹ ) _m (I) [In the formula (I), M represents at least one selected from the group consisting of Al, Nb, Ta, VO, Y, and Hf; and R ¹ independently represents an alkyl group Or aryl; m represents an integer from 1 to 5]

The composition for forming a passivation layer according to the above <1>, which comprises a hydrolyzate of the compound represented by the above formula (I).

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

[Chemical 1]

[In the formula (II), R ² each independently represents an alkyl group; n represents an integer of 1 to 3; and X ² and X ³ each independently represent an oxygen atom or a methylene group; and R ³ , R ⁴ and R ⁵ respectively Independently representing a hydrogen atom or an alkyl group]

<4> A semiconductor substrate with a passivation layer, comprising: a semiconductor substrate; and a passivation layer provided on at least a portion of at least one surface of the semiconductor substrate, and is any one of items <1> to <3> The heat treatment of the composition for forming a passivation layer.

The semiconductor substrate with a passivation layer according to the item <4>, wherein the passivation layer has an average thickness of 200 nm or less.

<6> A method of producing a semiconductor substrate with a passivation layer, comprising: forming a passivation layer forming composition according to any one of the items <1> to <3>, wherein at least one of the at least one surface of the semiconductor substrate is provided a step of forming a composition layer; and a step of heat-treating the composition layer to form a passivation layer.

The method for producing a semiconductor substrate with a passivation layer according to the above aspect, wherein the step of forming the composition for forming the passivation layer to form a composition layer includes a screen printing method.

<8> A solar cell element comprising: a semiconductor substrate having a pn junction portion in which a p-type layer and an n-type layer are pn-bonded; and a passivation layer provided on at least a part of at least one surface of the semiconductor substrate; The heat-treated product of the composition for forming a passivation layer according to any one of the items <1>, wherein the electrode is disposed on at least one of the p-type layer and the n-type layer.

The solar cell element according to the item <8>, wherein the passivation layer has an average thickness of 200 nm or less.

<10> A method of manufacturing a solar cell element, comprising: providing at least a part of at least one surface of a semiconductor substrate having a pn junction portion in which a p-type layer and an n-type layer are pn-bonded, as given in item <1> to item <3> The step of forming a composition layer by the composition for forming a passivation layer according to any one of the preceding claims; the step of heat-treating the composition layer to form a passivation layer; and the p-type layer and the n The step of arranging electrodes on at least one of the layers of the layer.

The method for producing a solar cell element according to the above aspect, wherein the step of forming the composition for forming the passivation layer to form a composition layer includes a screen printing method.

<12> A solar cell comprising: the solar cell element according to the item <8> or <9>; and a wiring material disposed on the electrode of the solar cell element. [Effects of the Invention]

According to an embodiment of the present invention, it is possible to provide a composition for forming a passivation layer of a passivation layer which is excellent in film quality, excellent in pattern formation property, and excellent in passivation effect by a simple method. Moreover, according to one embodiment of the present invention, it is possible to provide a semiconductor substrate with a passivation layer having a passivation layer having excellent film quality and excellent pattern formation property, a method for producing the same, and a solar cell having excellent conversion efficiency. A component and a method of manufacturing the same, and a solar cell having excellent conversion efficiency.

Hereinafter, the composition for forming a passivation layer of the present invention, a semiconductor substrate with a passivation layer, a method for producing the same, a solar cell element, a method for producing the same, and a form for carrying out a solar cell will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including the element steps and the like) are not necessarily required unless otherwise specified, and considered to be essential in principle. The same is true for the numerical values and ranges thereof, and does not limit the invention. In the present specification, the term "step" is not only an independent step, but even if it cannot be clearly distinguished from other steps, it is included in the term as long as the purpose of the step can be achieved. In addition, the numerical range represented by "~" indicates the range in which the numerical values described before and after "~" are respectively the minimum value and the maximum value. Further, when a plurality of substances corresponding to the respective components are present in the composition in the content of each component in the composition, unless otherwise specified, the total amount of the plurality of substances present in the composition is referred to. In addition, in the present specification, the term "layer" is a plan view, and includes a configuration in which a shape is formed in addition to a shape formed on the entire surface. In addition, in this specification, a "layer" may be called "film."

<The composition for forming a passivation layer> The composition for forming a passivation layer of the present embodiment is a composition for forming a passivation layer, which comprises a compound represented by the following formula (I) (hereinafter also referred to as a compound of the formula (I) And water is applied to the semiconductor substrate by a printing method to form a passivation layer having an average thickness of 200 nm or less after the heat treatment.

M(OR ¹ ) _m (I)

In the formula (I), M represents at least one selected from the group consisting of Al, Nb, Ta, VO, Y, and Hf. R ¹ each independently represents an alkyl group or an aryl group. m represents an integer of 1 to 5.

The passivation layer having an average thickness of 200 nm or less can be formed by a printing method, whereby a passivation layer excellent in pattern formability and excellent in passivation effect can be formed by a simple method.

The composition for forming a passivation layer of the present embodiment contains the compound of the formula (I) and water. Further, the composition for forming a passivation layer of the present embodiment may further contain a hydrolyzate of the compound of the formula (I). The composition for forming a passivation layer of the present embodiment may further contain other components as needed. In the composition for forming a passivation layer of the present embodiment, the passivation layer having excellent pattern formation property and excellent passivation effect can be formed by a simple method.

The inventors of the present invention conducted diligent research and found that although the mechanism is not clear, the thixotropy of the composition is improved by allowing water to act on the compound of the formula (I). The composition for forming a passivation layer of the present embodiment contains a compound of the formula (I) and water, and a high shear rate and a low shear rate of the composition for forming a passivation layer by allowing water to act on the compound of the formula (I). The viscosity ratio at that time is increased as the thixotropic ratio. As a result, it is presumed that the composition for forming a passivation layer of the present embodiment is excellent in pattern formability. The composition for forming a passivation layer of the present embodiment is improved in thixotropy by applying water to the compound of the formula (I), and the composition of the composition layer formed by imparting the composition for forming a passivation layer onto the semiconductor substrate is stable. Further, the passivation layer can be formed in a desired shape in a region where the composition layer is formed. Therefore, in the composition for forming a passivation layer of the present embodiment, at least one of a thixotropic agent and a resin to be described later is not required in order to exhibit desired thixotropy (hereinafter, a thixotropic agent and a resin may be used in some cases). At least one of them is called a thixotropic agent or the like, or even if a thixotropic agent or the like is used, the amount of addition can be reduced as compared with the composition for forming a passivation layer. When a passivation layer is formed using a composition for forming a passivation layer containing a thixotropic agent or the like composed of an organic substance, the thixotropic agent or the like is thermally decomposed and scattered from the passivation layer by a step of degreasing treatment. However, even in the step of the degreasing treatment, a thermal decomposition product such as a thixotropic agent remains in the passivation layer as an impurity, and a thermal decomposition product such as a thixotropic agent remaining may cause deterioration of characteristics of the passivation layer. Happening. On the other hand, in the case where a passivation layer is formed using a composition for forming a passivation layer containing a thixotropic agent composed of an inorganic material, even if a heat treatment (calcination) step is performed, the thixotropic agent does not scatter and remains in passivation. In the layer. The residual thixotropic agent causes deterioration of the characteristics of the passivation layer. On the other hand, in the composition for forming a passivation layer of the present embodiment, water is allowed to act on the compound of the formula (I), and water or a hydrolyzate of the compound of the formula (I) acts as a thixotropic agent. In the case where the passivation layer forming composition is used to form the passivation layer, water is more likely to scatter from the passivation layer than the previous thixotropic agent or the like in the heat treatment (calcination) step or the like to be performed. Therefore, it is difficult to cause a decrease in the passivation effect of the passivation layer due to the presence of the residue in the passivation layer. Further, it is easy to achieve a desired average thickness of 200 nm or less by reducing the amount of the remaining matter.

In order to achieve a desired passivation layer having an average thickness of 200 nm or less using a composition for forming a passivation layer, the following method can be mentioned. One method is to reduce the content of components remaining after heat treatment (calcination) of the composition for forming a passivation layer. It is easy to achieve a desired average thickness of 200 nm or less by reducing the amount of residual matter.

Further, another method is to reduce the amount of the composition for forming a passivation layer imparted on the semiconductor substrate. By reducing the amount of the composition for forming a passivation layer to be applied, the amount of the substance remaining in the passivation layer is reduced, and the desired average thickness of 200 nm or less is easily achieved.

In the present specification, the passivation effect of the semiconductor substrate can be evaluated by using a device such as WT-2000PVN manufactured by SEMILAB Co., Ltd., by means of a reflected microwave photoconductive attenuation method. The lifetime of a few carriers within the semiconductor substrate of the passivation layer.

Here, the effective life τ is expressed by the following formula (A) by the block life τ _b inside the semiconductor substrate and the surface life τ _{s of the} surface of the semiconductor substrate. When the surface level density of the surface of the semiconductor substrate is small, τ _s becomes long, and as a result, the effective lifetime τ becomes long. Further, even if defects such as dangling bonds in the semiconductor substrate are reduced, the block life τ _b becomes long and the effective life τ becomes long. That is, the interface characteristics of the passivation layer and the semiconductor substrate and the internal characteristics of the semiconductor substrate such as dangling bonds can be evaluated by measuring the effective lifetime τ.

1/τ=1/τ _b +1/τ _s (A)

Furthermore, the longer the effective life, the slower the recombination speed of a few carriers. Further, by using a semiconductor substrate having a long effective life to form a solar cell element, conversion efficiency is improved.

(Compound represented by the formula (I) and a hydrolyzate thereof) The composition for forming a passivation layer of the present embodiment contains at least one of the compounds of the formula (I). Further, the composition for forming a passivation layer of the present embodiment may further contain a hydrolyzate of at least one of the compounds of the formula (I). The passivation layer-forming composition of the present embodiment contains at least one of the compounds of the formula (I), and a passivation layer having an excellent passivation effect can be formed. The reason can be considered as follows.

It is considered that a metal oxide formed by heat-treating (calcining) a composition for forming a passivation layer containing a compound of the formula (I) or a hydrolyzate thereof has a defect of a metal atom or an oxygen atom, and a fixed charge is easily generated. By generating charges in the vicinity of the interface of the semiconductor substrate by the fixed charges, the concentration of a small number of carriers can be lowered, and as a result, it is considered that the carrier recombination speed at the interface is suppressed and an excellent passivation effect is obtained.

Here, the state of the passivation layer which generates a fixed charge on the semiconductor substrate can be evaluated by using the electron energy of a scanning transmission electron microscope (STEM) for the cross section of the semiconductor substrate. Analysis of the Electron Energy Loss Spectroscopy (EELS) to study the binding mode. Further, by measuring the X-ray diffraction spectrum (XRD), the crystal phase in the vicinity of the interface of the passivation layer was confirmed. Further, the fixed charge of the passivation layer can be evaluated by Capacitance Voltage Measurement (CV).

In the formula (I), M is at least one selected from the group consisting of Al, Nb, Ta, VO, Y, and Hf, and the passivation effect, pattern formation property of the passivation layer-forming composition, and preparation passivation From the viewpoint of operability in forming a composition for a layer, it is preferable that M is at least one selected from the group consisting of Al, Nb, Ta, and Y, and the thixotropy of the composition for forming a passivation layer is preferable. In terms of opinion, it is better to be Nb.

In the formula (I), R ¹ each independently represents an alkyl group or an aryl group, preferably an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms, more preferably 1 to 8 carbon atoms. The alkyl group is 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 a methyl group, an ethyl group, a n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a second butyl group, a tert-butyl group, a hexyl group, and a octyl group. Base, ethylhexyl and the like. Specific examples of the aryl group represented by R ¹ include a phenyl group. The alkyl group and the aryl group represented by R ¹ may have a substituent. The substituent of the alkyl group may, for example, be an amine group, a hydroxyl group, a carboxyl group, a sulfo group or a nitro group. Examples of the substituent of the aryl group include a methyl group, an ethyl group, an isopropyl group, an amine group, a hydroxyl group, a carboxyl group, a sulfo group, and a nitro group. Among them, from the viewpoint of reactivity with water and a passivation effect, R ^{1 is} preferably an unsubstituted alkyl group having 1 to 8 carbon atoms, more preferably an unsubstituted alkyl group having 1 to 4 carbon atoms.

In the formula (I), m represents an integer of 1 to 5. Here, from the viewpoint of reactivity with water, when M is Al, m is preferably 3, and when M is Nb, m is preferably 5, and when M is Ta, m is preferably 5, and when M is VO, m is preferably 3, and when M is Y, m is preferably 3, and when M is Hf, m is preferably 4.

As the compound of the formula (I), it is preferred that M is at least one selected from the group consisting of Al, Nb, Ta and Y, and R ¹ is an unsubstituted alkyl group having 1 to 4 carbon atoms, and m It is an integer of 1 to 5.

The state of the compound of formula (I) may be a solid at 25 ° C or a liquid. The compound of the formula (I) is preferably a viewpoint of the storage stability of the composition for forming a passivation layer of the present embodiment, the miscibility with water, and the mixing property of the compound represented by the following formula (II). It is a liquid at 25 °C.

Specific examples of the compound of the formula (I) include aluminum oxide, acetyl alumina, isopropyl alumina, n-propane aluminum oxide, n-butyl alumina, third butadiene alumina, isobutyl alumina, and ruthenium oxyhydroxide. , niobium ethoxide, bismuth oxyhydroxide, bismuth oxyhydroxide, bismuth ruthenium oxychloride, ruthenium tributoxide, ruthenium ruthenium oxide, ruthenium oxyhydroxide, ruthenium ethoxide, bismuth isopropoxide, n-propyl Cerium oxide, n-butyl cerium oxide, cerium tributyl cerium oxide, cerium ytterbium oxide, cerium oxyhydroxide, cerium oxide, cerium isopropoxide, cerium oxynide, cerium n-butyl cerium oxide, cerium tributyl cerium oxide, cerium Cerium oxide, methoxy vanadium oxide, ethoxylated vanadium oxide, isopropoxy vanadium oxide, n-propoxy vanadium oxide, n-butoxy vanadium oxide, third butoxy vanadium oxide, isobutoxy vanadium oxide , cerium oxide, cerium oxide, cerium isopropoxide, cerium oxynide, cerium n-butyl cerium oxide, cerium tributyl cerium oxide, cerium isobutyl cerium oxide, etc., among which, acetyl alumina, isopropyl alumina, Butadiene alumina, yttrium oxide, n-propoxide, n-butyl ruthenium oxide, ruthenium oxyhydroxide, n-propoxide Antimony, n-butyl cerium oxide, cerium isopropoxide and n-butyl cerium oxide.

Further, the compound of the formula (I) can be used as it is, and a commercially available product can also be used. As a commercial item, for example, pentamethoxy hydrazine, pentaethoxy hydrazine, pentaisopropoxy fluorene, penta-n-propoxy fluorene, and penta-isobutoxy fluorene of High Purity Chemical Research Institute Co., Ltd. , penta-n-butoxy fluorene, penta-butoxy fluorene, pentamethoxy fluorene, pentaethoxy hydrazine, pentaisopropoxy hydrazine, penta-n-propoxy fluorene, penta-isobutoxy fluorene, five n-Butoxy fluorene, penta-butoxy quinone, penta-butoxy fluorene, trimethyl oxide vanadium oxide (V), triethoxy vanadium oxide (V), triisopropoxide vanadium oxide (V) ), tri-n-propoxide vanadium oxide (V), tri-isobutyl oxide vanadium oxide (V), tri-n-butoxide oxide vanadium (V), three second butoxide oxide vanadium (V), three third Butane oxide vanadium oxide (V), triisopropoxy ruthenium, tri-n-butoxy ruthenium, tetramethoxy ruthenium, tetraethoxy ruthenium, tetraisopropoxy ruthenium, tetra-tert-butoxy ruthenium, Tetraethoxy ruthenium, pentaethoxy ruthenium, pentabutoxy ruthenium, n-butyl ruthenium oxide, ruthenium ruthenium oxide, and triethoxy oxidation of Nichia Chemical Industry Co., Ltd. , Tri-n-propoxy, vanadium oxide, vanadium oxide tri-n-butoxy, isobutoxy three vanadium oxide, tri-butoxy vanadium oxide.

In the preparation of the compound of the formula (I), a known method can be employed in which a specific metal (M) halide is reacted with an alcohol in the presence of an inert organic solvent, and ammonia or an amine is added for the purpose of extracting halogen. A method of the type is disclosed in Japanese Laid-Open Patent Publication No. SHO63-227593, and Japanese Patent Application Laid-Open No. Hei No. 3-291247.

A part of the compound of the formula (I) may be contained in the composition for forming a passivation layer of the present embodiment in the form of a compound having a chelate structure by mixing with a compound having a specific structure having two carbonyl groups described later.

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

The content of the compound of the formula (I) contained in the composition for forming a passivation layer of the present embodiment can be appropriately selected as needed. The content of the compound of the formula (I) is from 0.1% by mass to 80% by mass, preferably from 0.5% by mass to 70%, based on the reactivity of the water and the passivation effect. The mass% is more preferably from 1% by mass to 60% by mass, still more preferably from 1% by mass to 50% by mass.

The content rate of the hydrolyzate of the compound of the formula (I) which may be contained in the composition for forming a passivation layer of the present embodiment is appropriately selected as needed. From the viewpoint of the passivation effect, the content of the hydrolyzate of the compound of the formula (I) can be 0.1% by mass to 80% by mass, preferably 0.5% by mass, based on the composition for forming a passivation layer of the present embodiment. 70% by mass, more preferably 1% by mass to 60% by mass, still more preferably 1% by mass to 50% by mass. Further, in the present embodiment, the hydrolyzate of the compound of the formula (I) means a decomposition product of hydrolysis of the compound of the formula (I) obtained by adding water to the compound of the formula (I).

(Water) The composition for forming a passivation layer of the present embodiment contains water. The composition for forming a passivation layer of the present embodiment contains water to form a composition for forming a passivation layer having excellent pattern formation properties. The reason can be considered as follows.

In the composition for forming a passivation layer of the present embodiment, at least a part of the compound of the formula (I) is reacted with at least a part of water. It is considered that the metal compound formed by the reaction of water with the compound of the formula (I), that is, the hydrolyzate of the compound of the formula (I), forms a network with each other by using a metal compound. In addition, it is considered that the network is easily deformed when the composition for forming a passivation layer flows, and is formed again when the composition for forming a passivation layer is again in a stationary state. This network enhances the viscosity when the composition for forming a passivation layer is stationary, and lowers the viscosity when the composition for forming a passivation layer flows. As a result, it is considered that the composition for forming a passivation layer exhibits a desired thixotropy in terms of pattern formability.

A passivation layer of a desired shape can be formed by using a composition for forming a passivation layer having excellent pattern formability. Therefore, an excellent semiconductor substrate with a passivation layer, a solar cell element, and a solar cell can be manufactured.

The state of the water can be solid or liquid. From the viewpoint of the miscibility with the compound of the formula (I), the water is preferably a liquid.

The content ratio of water contained in the composition for forming a passivation layer of the present embodiment can be appropriately selected as needed. In view of the thixotropy of the composition for forming a passivation layer of the present embodiment, the water content of the composition for forming a passivation layer of the present embodiment is 0.01% by mass or more, preferably 0.03% by mass. The above is more preferably 0.05% by mass or more, and still more preferably 0.1% by mass or more. In addition, the water content of the composition for forming a passivation layer of the present embodiment is 0.01% by mass to 80% by mass, preferably 0.03% by mass to 70%, from the viewpoint of the patterning property and the passivation effect. The mass% is more preferably 0.05% by mass to 60% by mass, still more preferably 0.1% by mass to 50% by mass.

In the composition for forming a passivation layer, the amount of water acting on the compound of the formula (I) can be calculated from the amount of the free alcohol in the compound of the formula (I). When water acts on the compound of formula (I), the alcohol, R ¹ OH, is freed from the compound of formula (I). The amount of free alcohol is proportional to the amount of functional groups of the compound of formula (I) to which water acts. Thus, by measuring the amount of free alcohol, the amount of water acting on the compound of formula (I) can be calculated. The amount of free alcohol can be confirmed, for example, by Gas Chromatography-Mass Spectrometry (GC-MS).

In the case where cerium oxide is selected from the compound of the formula (I), ethanol is released when water acts. Among alcohols, ethanol is less toxic to humans. Therefore, a material having less adverse effects on the human body is formed by selecting cerium oxide in the compound of the formula (I).

The content of the free R ¹ OH contained in the alcohol contained in the composition for forming a passivation layer is preferably 0.5% by mass to 70% by mass, more preferably 1% by mass to 60% by mass, still more preferably 1% by mass. ~ 50% by mass.

(Compound represented by the formula (II)) The passivation layer-forming composition of the present embodiment may contain at least one of the compounds represented by the following formula (II) (hereinafter referred to as "organoaluminum compound").

[Chemical 2]

In the formula (II), R ² each independently represents an alkyl group. n represents an integer of 1 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.

According to the composition for forming a passivation layer of the present embodiment, the organic aluminum compound is contained, and the passivation effect can be further improved. It can be considered in the form as described below.

The organoaluminum compound preferably contains a compound referred to as an alkane alumina, an aluminum chelate or the like, and has an aluminum chelate structure in addition to the alkoxylated alumina structure. In addition, as described in "Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi", vol. 97, pp369-399 (1989), an organoaluminum compound is formed by heat treatment (calcination) to form alumina ( Al ₂ O ₃ ). At this time, since the formed alumina is likely to be in an amorphous state, it is considered that the 4-coordinated alumina layer is easily formed in the vicinity of the interface with the semiconductor substrate, and may have a large negative fixed charge due to the 4-coordinate alumina. At this time, it is considered that by combining with a compound of the formula (I) having a fixed charge or an oxide derived from the hydrolyzate thereof, a passivation layer having an excellent passivation effect can be formed as a result.

In addition to the above, it is also considered that by combining the compound of the formula (I) with an organoaluminum compound as in the present embodiment, the effect of each in the passivation layer is utilized, and the passivation effect becomes higher. Further, it is considered that the composite metal alkane oxidation of the metal (M) and aluminum (Al) contained in the compound of the formula (I) is carried out by heat treatment (calcination) in a state in which the compound of the formula (I) and the organoaluminum compound are mixed. The physical properties such as the reactivity of the substance and the vapor pressure are improved, and the denseness of the passivation layer as the heat-treated product (calcined product) is improved, and as a result, the passivation effect is further improved.

In the formula (II), R ² each independently represents an alkyl group, preferably an alkyl group having 1 to 8 carbon atoms, more 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 a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a second butyl group, a tert-butyl group, a hexyl group, and a octyl group. Base, ethylhexyl and the like. Among them, from the viewpoint of storage stability and passivation effect, the alkyl group represented by R ² is preferably an unsubstituted alkyl group having 1 to 8 carbon atoms, more preferably an unsubstituted carbon group having 1 to 4 carbon atoms. alkyl.

In the formula (II), n represents an integer of 1 to 3. From the viewpoint of storage stability, n is preferably 1 or 3, and more preferably 1 in terms of solubility. Further, 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 formula (II) each independently represent a hydrogen atom or an alkyl group. 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 is preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms. Specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a second butyl group, a tert-butyl group, a hexyl group, an octyl group, an ethylhexyl group and the like.

In view of the storage stability and the passivation effect, R ³ and R ⁴ are each independently preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 8 carbon atoms, more preferably a hydrogen atom or a carbon number of 1. ～4 unsubstituted alkyl group. Further, from the viewpoint of storage stability and passivation effect, R ^{5 is} preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 8 carbon atoms, more preferably a hydrogen atom or an unsubstituted carbon number of 1 to 4. Alkyl.

From the viewpoint of storage stability, the organoaluminum compound is preferably a compound wherein n is an integer of 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 and passivation effect, the organoaluminum compound is preferably a compound wherein n is an integer of 1 to 3, and R ^{2 is} independently an alkyl group having 1 to 4 carbon atoms, X ² and X ³ . At least one of them is an oxygen atom, and each of R ³ and R ^{4 is} independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ⁵ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The organoaluminum compound is more preferably a compound wherein n is an integer of 1 to 3, R ^{2 is} independently an unsubstituted alkyl group having 1 to 4 carbon atoms, and at least one of X ² and X ³ is an oxygen atom or a bond. R ³ or R ^{4 which} is bonded to the oxygen atom is 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.

In addition, specific examples of the organoaluminum compound in which n is an integer of from 1 to 3 represented by the formula (II) include ethyl acetate ethyl diisopropylate and aluminum tris(ethyl acetate) aluminum.

Further, the organoaluminum compound in which n is an integer of 1 to 3 represented by the formula (II) can be used as it is, and a commercially available product can also be used. As a commercial item, the brand name ALCH, ALCH-50F, ALCH-75, ALCH-TR, ALCH-TR-20, etc. of the Fine Chemicals Co., Ltd. are mentioned, for example.

Further, the organoaluminum compound in which n is an integer of 1 to 3 represented by the formula (II) can be produced by mixing a triall alumina with a compound having a specific structure having two carbonyl groups described below. Further, a commercially available aluminum chelate compound can also be used. When the trioxane alumina is mixed with a compound having a specific structure of two carbonyl groups, at least a part of the alkoxide group of the triane alumina is substituted with a compound of a specific structure to form an aluminum chelate structure. At this time, a liquid medium may be present as needed, and heat treatment, addition of a catalyst, or the like may be performed. When at least a part of the alkoxide structure is substituted with an aluminum chelate structure, the stability of the organoaluminum compound to hydrolysis and polymerization is improved, and the storage stability of the composition for forming a passivation layer containing the organoaluminum compound is further improved.

From the viewpoint of reactivity and storage stability, a compound having a specific structure of two carbonyl groups is preferably selected from the group consisting of a β-diketone compound, a β-ketoester compound, and a malonic acid diester. At least one of them. Specific examples of the compound having two specific structures of a carbonyl group include acetamidineacetone, 3-methyl-2,4-pentanedione, 2,3-pentanedione, and 3-ethyl-2,4. -pentanedione, 3-butyl-2,4-pentanedione, 2,2,6,6-tetramethyl-3,5-heptanedione, 2,6-dimethyl-3,5- a β-diketone compound such as heptanedione or 6-methyl-2,4-heptanedione, methyl ethyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, and Isobutyl phthalate acetate, n-butyl acetate, n-butyl acetate, n-butyl acetate, n-amyl acetate, isoamyl acetate, n-hexyl acetate, n-octyl acetate, acetamidine N-heptyl acetate, 3-pentyl acetate, ethyl 2-acetate, ethyl 2-methylacetate, ethyl 2-butylacetate, ethyl hexylacetate, 4 , 4-dimethyl-3-oxopentanoate ethyl ester, 4-methyl-3-oxopentanoate ethyl ester, 2-ethylacetic acid ethyl acetate, 4-methyl-3-oxo-pentane Methyl ester, ethyl 3-oxohexanoate, ethyl 3-oxopentanoate, methyl 3-oxopentanoate, methyl 3-oxohexanoate, ethyl 3-oxoheptanoate, 3 - Methyl oxoheptanoate, 4,4-dimethyl-3-oxo a β-ketoester compound such as methyl valerate, dimethyl malonate, diethyl malonate, di-n-propyl malonate, diisopropyl malonate, di-n-butyl malonate, C Di-tert-butyl diacid, dihexyl malonate, tert-butyl ethyl malonate, diethyl methyl malonate, diethyl ethyl malonate, isopropyl malonate Ethyl malonate, diethyl butyl butyl malonate, diethyl butyl dimethyl malonate, diethyl isobutyl malonate, diethyl 1-methylbutyl malonate Diester and the like.

The amount of the aluminum chelate structure can be controlled, for example, by appropriately adjusting the ratio of mixing the trioxane alumina with a compound having a specific structure of two carbonyl groups. Further, a compound having a desired structure can be suitably selected from commercially available aluminum chelate compounds.

In the organoaluminum compound, from the viewpoint of the passivation effect and compatibility with a solvent contained as necessary, it is particularly preferred to use an ethyl aluminum diisopropylate and a triisopropoxy group selected from ethyl acetate. At least one of the groups consisting of aluminum is more preferably ethylacetate ethylaluminum diisopropoxide.

The presence of the aluminum chelate structure in the organoaluminum compound can be confirmed by an analytical method generally used. For example, it can be confirmed using an infrared spectroscopic spectrum, a nuclear magnetic resonance spectrum, a melting point, or the like.

The organoaluminum compound may be in a liquid state or a solid, and is not particularly limited. From the viewpoint of the passivation effect and the storage stability, the homogeneity of the formed passivation layer is further improved by using the stability at normal temperature (25 ° C) and the organoaluminum compound having good solubility or dispersibility. The desired passivation effect is stably obtained.

When the composition for forming a passivation layer of the present embodiment contains an organoaluminum compound, the content of the organoaluminum compound is not particularly limited. In particular, the content of the organoaluminum compound when the total content of the hydrolyzate of the compound of the formula (I) and the organoaluminum compound contained in the compound of the formula (I) and the organoaluminum compound is 100% by mass is preferably 0.5% by mass. ～80% by mass, more preferably 1% by mass to 75% by mass, still more preferably 2% by mass to 70% by mass, particularly preferably 3% by mass to 70% by mass. When the content of the organoaluminum compound is 0.5% by mass or more, the passivation effect tends to be improved. In addition, when the amount of the organoaluminum compound is 80% by mass or less, the storage stability of the composition for forming a passivation layer tends to be improved.

In the case where the composition for forming a passivation layer of the present embodiment contains an organoaluminum compound, the content of the organoaluminum compound in the composition for forming a passivation layer can be appropriately selected as needed. The content of the organoaluminum compound can be 0.1% by mass to 60% by mass, preferably 0.5% by mass to 55% by mass, more preferably 0.5% by mass to 55% by mass, based on the storage stability and the passivation effect. It is preferably from 1% by mass to 50% by mass, and more preferably from 1% by mass to 45% by mass.

(Liquid Medium) The composition for forming a passivation layer of the present embodiment may contain a liquid medium (solvent or dispersion medium). Since the composition for forming a passivation layer contains a liquid medium, the adjustment of the viscosity becomes easier, the impartability is further improved, and a more uniform passivation layer can be formed. The liquid medium is not particularly limited and may be appropriately selected as needed. Among them, a liquid medium in which a compound of the formula (I) and an organoaluminum compound to be added as needed are dissolved to form a uniform solution is preferred, and at least one of organic solvents is more preferred. The liquid medium refers to a medium in a state of being liquid at room temperature (25 ° C).

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, and methyl n-pentyl Ketone, methyl n-hexyl ketone, diethyl ketone, di-n-acetone, diisobutyl ketone, trimethyl fluorenone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2,4-pentanedione, Ketone solvent such as acetone-acetone, diethyl ether, methyl ethyl ether, methyl n-propyl ether, diisopropyl ether, tetrahydrofuran, methyl tetrahydrofuran, dioxane, dimethyl dioxane, ethylene glycol Ether, ethylene glycol diethyl ether, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, two Ethylene 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, three Ethylene 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 glycol methyl n-Hexyl ether, tetraethylene glycol dimethyl ether, four Ethylene 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, propylene glycol dimethyl ether , propylene glycol diethyl ether, propylene glycol di-n-propyl ether, propylene glycol di-n-butyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol methyl ethyl ether, dipropylene glycol methyl 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, tetrapropylene glycol methyl n-butyl ether, tetrapropylene glycol methyl n-hexyl ether, tetrapropylene glycol di-n-butyl Ether solvent such as butyl ether, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, dibutyl acetate, n-amyl acetate, diamyl acetate , 3-methoxybutyl acetate, methyl amyl acetate, B 2-ethylbutyl ester, 2-ethylhexyl acetate, 2-(2-butoxyethoxy)ethyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, decyl acetate , ethyl acetate methyl acetate, ethyl acetate, diethylene glycol methyl ether, diethylene glycol monoethyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, diacetin, acetic acid methoxy Triethylene glycol ester, isoamyl acetate, ethyl propionate, n-butyl propionate, isoamyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate Ester, 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 ether Ester ester solvents such as acetate, propylene glycol propyl ether acetate, γ-butyrolactone, γ-valerolactone, acetonitrile, N-methylpyrrolidone, N-ethylpyrrolidone, N-n-propylpyrrole Iridone, N-n-butyl pyrrolidone, N-n-hexyl pyrrolidone, N-cyclohexyl pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, Aprotic benzoquinone Polar solvent, hydrophobic organic solvent such as methylene chloride, chloroform, dichloroethane, benzene, toluene, xylene, hexane, octane, ethylbenzene or 2-ethylhexane acid, methanol , ethanol, n-propanol, isopropanol, n-butanol, isobutanol, second butanol, third butanol, n-pentanol, isoamyl alcohol, 2-methylbutanol, second pentanol, Triamyl alcohol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, second hexanol, 2-ethylbutanol, second heptanol, n-octanol, 2-ethylhexanol, Second octanol, n-nonanol, n-nonanol, second-undecyl alcohol, trimethyl decyl alcohol, second-tetradecanol, second heptadecyl alcohol, cyclohexanol, methyl ring An alcohol solvent such as hexanol, benzyl alcohol, ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol or tripropylene glycol, 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, ethoxy triglyceride Alcohol, tetraethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, dipropylene glycol a glycol monoether solvent such as methyl ether, dipropylene glycol monoethyl ether or tripropylene glycol monomethyl ether, terpinene, terpineol, myrcene, allolocene, limonene, dipentene, terpene, fragrant celery a terpene solvent such as carvone, ocimene or phellandrene. These liquid mediums may be used alone or in combination of two or more.

In view of the impartability and pattern formation property of the semiconductor substrate, 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 more preferably contains a liquid. At least one of the group consisting of free terpene solvents.

When the composition for forming a passivation layer contains a liquid medium, the content of the liquid medium is determined in consideration of impartability, pattern formation property, and storage stability. For example, the content of the liquid medium is preferably from 5% by mass to 98% by mass, more preferably 10% by mass based on the total mass of the composition for forming a passivation layer, from the viewpoint of the impartability of the composition and the pattern formation property. % to 95% by mass.

(Resin) The composition for forming a passivation layer of the present embodiment may further contain at least one of resins. By including the resin, the shape stability of the composition layer formed by imparting the composition for forming a passivation layer of the present embodiment to the semiconductor substrate is further improved, and the passivation layer can be formed in a desired shape in the formation of the composition layer. In the area.

The kind of the resin is not particularly limited. When the composition for forming a passivation layer of the present embodiment is applied to a semiconductor substrate, the resin can be adjusted to have a viscosity within a range in which a favorable pattern can be formed. Specific examples of the resin include polyvinyl alcohol, polypropylene decylamine, polypropylene decylamine derivative, polyvinyl decylamine, polyvinyl decylamine derivative, polyvinylpyrrolidone, and polyethylene oxide. Alkane, polyethylene oxide derivatives, polysulfonic acid, polypropylene decylalkylsulfonic acid, cellulose, cellulose derivatives (carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose, etc. Ether, etc.), gelatin, gelatin derivatives, starch, starch derivatives, sodium alginate, sodium alginate derivatives, Xanthan, Sanxian gum derivatives, guar gum, guar gum derivatives, hard Dextran, scleroglucan derivative, tragacanth, xanthan gum derivative, dextrin, dextrin derivative, (meth)acrylic resin, (meth) acrylate resin ((meth) acrylate A base resin, a dimethylaminoethyl (meth)acrylate resin, etc.), a butadiene resin, a styrene resin, a decyl alkane resin, a copolymer of these, and the like. These resins may be used alone or in combination of two or more. Further, in the present embodiment, (meth)acrylic acid means acrylic acid or methacrylic acid, and (meth)acrylic acid ester means acrylate or methacrylate.

Among these resins, from the viewpoint of storage stability and pattern formation, it is preferred to use a neutral resin having no acidic or basic functional groups, and it is easy to adjust even when the content is small. From the viewpoint of viscosity and thixotropy, it is more preferred to use a cellulose derivative. Further, the molecular weight of the resins is not particularly limited, and is preferably adjusted in view of the desired viscosity as a composition for forming a passivation layer. The weight average molecular weight of the resin is preferably from 1,000 to 10,000,000, more preferably from 1,000 to 5,000,000, from the viewpoint of storage stability and pattern formability. Further, the weight average molecular weight of the resin was determined by conversion using a calibration curve of standard polystyrene based on a molecular weight distribution measured by Gel Permeation Chromatography (GPC).

In the case where the composition for forming a passivation layer of the present embodiment contains a resin, the content of the resin in the composition for forming a passivation layer can be appropriately selected as needed. For example, the content of the resin is preferably from 0.1% by mass to 50% by mass based on the total mass of the composition for forming a passivation layer. From the viewpoint of exhibiting thixotropy such as pattern formation more easily, the content of the resin is more preferably 0.2% by mass to 25% by mass, still more preferably 0.5% by mass to 20% by mass, particularly preferably 0.5% by mass. ～15% by mass. Further, since the composition for forming a passivation layer of the present embodiment is excellent in thixotropic properties, the necessity of further exhibiting thixotropy of the resin is not high. Therefore, the content of the resin contained in the composition for forming a passivation layer of the present embodiment is preferably 0.5% by mass or less, more preferably 0.2% by mass or less, still more preferably 0.1% by mass or less, and particularly preferably substantially Resin free.

(Other components) In addition to the above components, the composition for forming a passivation layer of the present embodiment may further contain other components generally used in the field, as needed. The composition for forming a passivation layer of the present embodiment 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, the content of the acidic compound or the basic compound is preferably 1 in the composition for forming a passivation layer from the viewpoint of storage stability. The mass% or less is more preferably 0.1% by mass or less. Examples of the acidic compound include Bronsted acid and Lewis acid. Specific examples thereof include inorganic acids such as hydrochloric acid and nitric acid, and organic acids such as acetic acid. Further, examples of the basic compound include a Bruce base and a Lewis base. Specifically, examples of the basic compound include inorganic bases such as an alkali metal hydroxide and an alkaline earth metal hydroxide; and an organic base such as a trialkylamine or a pyridine.

Further, examples of the other component include a plasticizer, a dispersant, a surfactant, a thixotropic agent, other metal alkoxide compounds, and a high-boiling material. Among them, it is preferred to contain at least one selected from the group consisting of thixotropic agents. The shape stability of the composition layer formed by imparting the composition for forming a passivation layer of the present embodiment to the semiconductor substrate is further improved by including at least one selected from the group consisting of a thixotropic agent, and the passivation layer can be desired The shape is formed in a region where the composition layer is formed.

Examples of the thixotropic agent include a fatty acid guanamine, a polyalkylene glycol compound, an organic filler, and an inorganic filler. The polyalkylene glycol compound may, for example, be a compound represented by the following formula (III).

R ⁶ -(OR ⁸ ) _n -OR ⁷ 1⁄4(III)

In the 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. Further, R ⁸ in a plurality of (OR ⁸ ) may be the same or different.

Examples of the fatty acid guanamine include compounds represented by the following general formula (1), formula (2), formula (3), and formula (4).

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

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

Examples of the organic filler include an acrylic resin, a cellulose resin, and a polystyrene resin.

Examples of the inorganic filler include particles such as cerium oxide, aluminum hydroxide, aluminum nitride, cerium nitride, aluminum oxide, zirconium oxide, cerium carbide, and glass.

The volume average particle diameter of the organic filler or the inorganic filler is preferably from 0.01 μm to 50 μm. In the present embodiment, the volume average particle diameter of the filler can be measured by a laser diffraction scattering method.

Examples of the other metal alkoxide compound include a titanium alkoxide, a zirconium alkoxide, and a ruthenium alkoxide.

(High-boiling material) In the composition for forming a passivation layer of the present embodiment, a high-boiling material may be used as a material together with or in place of the resin. The high boiling point material is preferably a compound which is easily vaporized upon heating without requiring degreasing treatment. Further, the high-boiling material is particularly preferably a high-boiling high-boiling material which can maintain a printed shape after printing and coating. As a material satisfying these, for example, isobornylcyclohexanol can be mentioned.

Isobornylcyclohexanol is commercially available in the form of "Terusolve MTPH" (Japanese Terpene Chemical Co., Ltd., trade name). Isobornylcyclohexanol has a high boiling point of 308 ° C to 318 ° C. Further, when it is removed from the composition layer, it is not required to be subjected to heat treatment (calcination) degreasing treatment as a resin, and it can be vaporized by heating. This makes it disappear. Therefore, in the drying step after being applied to the semiconductor substrate, most of the solvent contained in the composition for forming a passivation layer and the isobornylcyclohexanol can be removed.

When the composition for forming a passivation layer of the present embodiment contains a high boiling point material, the content of the high boiling point material is preferably from 3% by mass to 95% by mass based on the total mass of the composition for forming a passivation layer. It is 5 mass% to 90 mass%, and more preferably 7 mass% to 80 mass%.

In addition, the composition for forming a passivation layer of the present embodiment may contain at least one oxide selected from the group consisting of Al, Nb, Ta, V, Y, and Hf (hereinafter referred to as "specific oxide"). . Since the specific oxide is an oxide formed by heat-treating (calcining) the compound of the formula (I), it is expected that the passivation layer formed of the composition for forming a passivation layer containing a specific oxide exhibits an excellent passivation effect.

The viscosity of the composition for forming a passivation layer of the present embodiment is not particularly limited, and can be appropriately selected depending on the method of applying the semiconductor substrate or the like. For example, the viscosity of the composition for forming a passivation layer can be set to 0.01 Pa·s to 100,000 Pa·s. Among them, the viscosity of the composition for forming a passivation layer is preferably from 0.1 Pa·s to 10,000 Pa·s in terms of pattern formability. Further, the viscosity was measured using a rotary shear viscometer at 25 ° C at a shear rate of 1.0 s ^-1 .

The method for producing the composition for forming a passivation layer of the present embodiment is not particularly limited. For example, it can be produced by mixing a compound of the formula (I), water, and optionally an organoaluminum compound, a liquid medium, a resin, or the like by a mixing method generally used. In addition, the content of each component and the content of each component in the composition for forming a passivation layer of the present embodiment can be thermally analyzed by thermogravimetry (TG)/differential thermal analysis (DTA) or nuclear magnetic resonance. (Nuclear Magnetic Resonance, NMR), infrared (Infrared Ray, IR) and other spectral analysis, high performance liquid chromatography (HPLC), GPC and other chromatographic analysis.

<Semiconductor Substrate with Passivation Layer> The semiconductor substrate with a passivation layer of the present embodiment includes a semiconductor substrate and a passivation layer, and the passivation layer is provided on at least a part of at least one surface of the semiconductor substrate, and is passivated in the present embodiment. A heat-treated product of the composition for layer formation. The semiconductor substrate with a passivation layer of the present embodiment exhibits an excellent passivation effect by providing a passivation layer which is a heat-treated product of the composition for forming a passivation layer of the present embodiment.

The semiconductor substrate is not particularly limited and may be appropriately selected from usual users depending on the purpose. Examples of the semiconductor substrate include a p-type impurity or an n-type impurity which is doped (diffused) in ruthenium, osmium or the like. Among them, a tantalum substrate is preferred. Further, the semiconductor substrate may be a p-type semiconductor substrate or an n-type semiconductor substrate. Among them, from the viewpoint of the passivation effect, a semiconductor substrate in which the surface on which the passivation layer is formed is a p-type layer is preferable. The p-type layer on the semiconductor substrate may be a p-type layer derived from a p-type semiconductor substrate, or may be formed on an n-type semiconductor substrate or a p-type semiconductor substrate in the form of a p-type diffusion layer or a p ⁺ -type diffusion layer.

Further, the thickness of the semiconductor substrate is not particularly limited and may be appropriately selected depending on the purpose. For example, the thickness of the semiconductor substrate can be set to 50 μm to 1000 μm, preferably 75 μm to 750 μm.

The average thickness of the passivation layer formed on the semiconductor substrate can be set to 200 nm or less. By setting the average thickness of the passivation layer to 200 nm or less, the thermal stress difference between the semiconductor substrate and the passivation layer which occurs when the semiconductor substrate with a passivation layer is sintered can be alleviated. By mitigating the thermal stress difference, cracking of the passivation layer can be prevented. When the number of cracks is small, deformation from a desired pattern shape is suppressed, and good pattern formability is obtained. Further, since the surface where the semiconductor substrate and the passivation layer are in contact with each other can be sufficiently ensured, good passivation characteristics are obtained.

The average thickness of the passivation layer formed on the semiconductor substrate may be 200 nm or less, preferably 5 nm to 200 nm, more preferably 10 nm to 190 nm, and still more preferably 15 nm to 180 nm. Furthermore, the average thickness of the passivation layer formed is determined by a conventional method using an automatic ellipsometer (for example, Five Labs, MARY-102) to determine the thickness of 9 points, and the arithmetic average thereof The form of the value is calculated.

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

<Manufacturing Method of Semiconductor Substrate with Passivation Layer> The method for producing a semiconductor substrate with a passivation layer according to the present embodiment includes forming a composition for forming a passivation layer of the present embodiment on at least a part of at least one surface of the semiconductor substrate. a step of constituting the layer; and a step of subjecting the composition layer to heat treatment (calcination) to form a passivation layer. The manufacturing method may also include other steps as needed. By using the composition for forming a passivation layer of the present embodiment, a passivation layer having excellent pattern formability and excellent passivation effect can be formed by a simple method.

The method for producing a semiconductor substrate with a passivation layer according to the present embodiment is preferably a step of providing an alkaline aqueous solution on a semiconductor substrate before the step of forming a composition layer. In other words, it is preferable to clean the surface of the semiconductor substrate with an alkaline aqueous solution before the composition for forming a passivation layer of the present embodiment is applied to the semiconductor substrate. By washing with an alkaline aqueous solution, organic substances, particles, and the like existing on the surface of the semiconductor substrate can be removed, and the passivation effect can be further improved. As a method of washing with an alkaline aqueous solution, a cleaning method using a commonly known RCA cleaning or the like can be exemplified. For example, the semiconductor substrate can be immersed in a mixed solution of aqueous ammonia-hydrogen peroxide water and treated at 60 to 80° C., whereby the organic matter and the particles are removed and washed. The cleaning time is preferably from 10 seconds to 10 minutes, more preferably from 30 seconds to 5 minutes.

In the step of forming the composition layer by applying the composition for forming a passivation layer of the present embodiment to the semiconductor substrate, it is preferable to include a printing method. Specific examples thereof include a screen printing method, an inkjet method, a dispenser method, a spin coating method, a brush coating method, a spray method, a doctor blade method, and a roll coating method. Among these, from the viewpoint of pattern formation property and productivity, a screen printing method, an inkjet method, and the like are preferable, and a screen printing method is more preferable.

The amount of the passivation layer-forming composition of the present embodiment can be appropriately selected in the range of the average thickness of the passivation layer to be 200 nm or less, depending on the purpose. The amount of the composition for forming the passivation layer is small, and the desired average thickness of 200 nm or less is easily achieved.

The composition layer formed of the composition for forming a passivation layer is subjected to heat treatment (calcination) to form a heat-treated material layer (calcined material layer) derived from the composition layer, whereby a passivation layer can be formed on the semiconductor substrate. The heat treatment (calcination) condition of the composition layer is such that the compound of the formula (I) contained in the composition layer and the organoaluminum compound contained as necessary can be converted into the heat-treated product (calcined product), that is, metal oxide or composite. The oxide is not particularly limited. In order to obtain a more excellent passivation effect by effectively forming a fixed charge in the passivation layer, specifically, the heat treatment (calcination) temperature is preferably from 300 ° C to 900 ° C, more preferably from 450 ° C to 800 ° C. Further, the heat treatment (calcination) time can be appropriately selected depending on the heat treatment (calcination) temperature and the like. For example, it can be set to 0.1 hour to 10 hours, preferably 0.2 hour to 5 hours.

In the method for producing a semiconductor substrate with a passivation layer of the present embodiment, the passivation layer forming composition of the present embodiment may be applied to the semiconductor substrate, and then the step of forming a passivation layer by heat treatment (calcination) may further include The step of drying the composition layer containing the composition for forming a passivation layer. By including a step of drying the composition layer, a more uniform passivation layer having a 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 water contained in the composition for forming a passivation layer and at least a part of the liquid medium which can be contained in the composition for forming a passivation layer can be removed. . The drying treatment may be, for example, heat treatment at 30 ° C to 250 ° C for 1 minute to 60 minutes, preferably at 40 ° C to 220 ° C for 3 minutes to 40 minutes. Further, the drying treatment can be carried out under normal pressure or under reduced pressure.

When the composition for forming a passivation layer contains a resin, the method for producing a semiconductor substrate with a passivation layer of the present embodiment may be a step of forming a passivation layer by heat treatment (calcination) after providing a composition for forming a passivation layer. Further, a step of degreasing the composition layer containing the composition for forming a passivation layer is further included. By including a step of degreasing the composition layer, a more uniform passivation layer having a passivation effect can be formed.

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

<Solar cell element> The solar cell element of the present embodiment includes a semiconductor substrate having a pn junction portion in which a p-type layer and an n-type layer are pn-bonded, and a passivation layer provided on at least one surface of the semiconductor substrate A part of the heat-treated product of the composition for forming a passivation layer of the present embodiment; and an electrode disposed on at least one of the p-type layer and the n-type layer. The solar cell element of the present embodiment may have other components as needed. The solar cell element of the present embodiment is excellent in conversion efficiency by having a passivation layer formed of the composition for forming a passivation layer of the present embodiment.

The semiconductor substrate to which the composition for forming a passivation layer of the present embodiment is applied is not particularly limited, and may be appropriately selected from ordinary users depending on the purpose. As the semiconductor substrate, the one described in the item of the semiconductor substrate with a passivation layer of the present embodiment can be used, and the user can be preferably the same. The surface of the semiconductor substrate provided with the passivation layer of the present embodiment is preferably the back surface of the solar cell element.

Further, the average thickness of the passivation layer formed on the semiconductor substrate can be appropriately selected in the range of 200 nm or less depending on the purpose. For example, the average thickness of the passivation layer is preferably from 5 nm to 200 nm, more preferably from 10 nm to 190 nm, and even more preferably from 15 nm to 180 nm. The shape and size of the solar cell element of the present embodiment are not limited. For example, it is preferably a substantially square having a side of 125 mm to 156 mm.

<Manufacturing Method of Solar Cell Element> The method of manufacturing a solar cell element according to the present embodiment includes: providing at least a part of at least one surface of a semiconductor substrate having a pn junction portion in which a p-type layer and an n-type layer are pn-bonded a step of forming a composition layer by the composition for forming a passivation layer of the present embodiment; a step of forming a passivation layer by heat-treating (calcining) the composition layer; and forming a passivation layer on the p-type layer and the n-type layer The step of arranging the electrodes on at least one of the layers. The method of manufacturing the solar cell element of the present embodiment may further include other steps as needed.

By using the composition for forming a passivation layer of the present embodiment, a solar cell element having excellent conversion efficiency can be produced by a simple method.

As a method of arranging the electrodes on at least one of the p-type layer and the n-type layer in the semiconductor substrate, a method generally used can be employed. For example, an electrode can be produced by applying a paste for forming an electrode such as a silver paste or an aluminum paste to a desired region of a semiconductor substrate, and performing heat treatment (calcination) as necessary.

The surface of the semiconductor substrate provided with the passivation layer of the present embodiment may be a p-type layer or an n-type layer. Among them, from the viewpoint of conversion efficiency, a p-type layer is preferred. The details of the method of forming the passivation layer using the composition for forming a passivation layer of the present embodiment are the same as those of the method for producing a semiconductor substrate with a passivation layer described above, and the preferred embodiment is also the same.

Next, a method of manufacturing a solar cell element of the present embodiment will be described with reference to the drawings. (1) to (9) of FIG. 1 are a cross-sectional view showing a step of an example of a method of manufacturing a solar cell element having a passivation layer according to the present embodiment. However, this step chart does not limit the invention in any way. Further, the size of the members in the respective drawings is conceptual, and the relative relationship between the sizes of the members is not limited thereto. In addition, in the case of a member having a common function, the same reference numerals are attached to all the drawings, and overlapping descriptions may be omitted.

In (1) of FIG. 1, the p-type semiconductor substrate 1 is cleaned with an alkaline aqueous solution, and organic substances, particles, and the like on the surface of the p-type semiconductor substrate 1 are removed. Thereby, the passivation effect is further improved. As a washing method using an alkaline aqueous solution, a method of using conventionally known RCA cleaning or the like can be mentioned.

Then, as shown in (2) of FIG. 1, the surface of the p-type semiconductor substrate 1 is subjected to alkali etching or the like to form irregularities (also referred to as textures) on the surface. Thereby, reflection of sunlight can be suppressed on the light receiving surface side. Further, in the alkali etching, an etching solution containing NaOH and Isopropyl Alcohol (IPA) can be used.

Then, as shown in (3) of FIG. 1, the n ⁺ -type diffusion layer 2 is formed in a thickness of a submicron order by thermally diffusing phosphorus or the like on the surface of the p-type semiconductor substrate 1, and A pn junction is formed with a boundary of the p-type bulk portion.

As a method for diffusing phosphorus, for example, a method of performing treatment at 800 ° C to 1000 ° C for several tens of minutes in a mixed gas atmosphere of phosphorus oxychloride (POCl ₃ ), nitrogen, and oxygen is exemplified. In this method, since phosphorus is diffused by using a mixed gas, as shown in (3) of FIG. 1, n ⁺ type diffusion is formed on the back surface and the side surface (not shown) in addition to the light receiving surface (surface). Layer 2. Further, on the n ⁺ -type diffusion layer 2, a Phosphosilicate Glass (PSG) layer 3 is formed. Therefore, side etching is performed, and the PSG layer 3 and the n ⁺ -type diffusion layer 2 on the side are removed.

Thereafter, as shown in (4) of FIG. 1, the PSG layer 3 on the light receiving surface and the back surface is removed using an etching solution such as hydrofluoric acid. Further, regarding the back surface, as shown in (5) of FIG. 1, an etching treatment is additionally performed to remove the n ⁺ -type diffusion layer 2 on the back surface.

Then, as shown in (6) of FIG. 1, an anti-reflection film 4 such as tantalum nitride is provided in a thickness of 90 nm by a plasma enhanced chemical vapor deposition (PECVD) method or the like. The light receiving surface is on the n ⁺ type diffusion layer 2 .

Then, as shown in (7) of FIG. 1, the composition for forming a passivation layer of the present embodiment is applied to a part of the back surface by screen printing or the like, and after drying, at 300 ° C to 900 ° C. The heat treatment (calcination) is performed at a temperature to form the passivation layer 5.

An example of the formation pattern of the passivation layer in the back surface is shown in a schematic plan view in FIG. Fig. 7 is a schematic plan view showing an enlarged portion A of Fig. 5; Fig. 8 is a schematic plan view showing an enlarged portion B of Fig. 5; In the case of forming a pattern of the passivation layer shown in FIG. 5, it can also be seen from FIGS. 7 and 8 that the passivation layer 5 on the back side is formed by a pattern in which the back side output is removed in addition to the subsequent steps. The p-type semiconductor substrate 1 is exposed in a dot shape in addition to the portion of the electrode 7. The pattern of the dot-shaped opening portion is preferably defined by a spot diameter (L _a ) and a dot interval (L _b ) and regularly arranged in a regular manner. The spot diameter (L _a) and the dot pitch (L _b) can be arbitrarily set, but in view of the passivation effect, and inhibition of recombination of minority carriers, the L _a is preferably 5 μm ~ 2 mm is 10 μm and L _b ～3 mm, more preferably L _a is 10 μm to 1.5 mm and L _b is 20 μm to 2.5 mm, more preferably L _a is 20 μm to 1.3 mm and L _b is 30 μm to 2 mm.

When the composition for forming a passivation layer has excellent pattern formability, the dot diameter (L _a ) and the dot pitch (L _b ) of the pattern of the dot-shaped opening portion are further regularly and accurately arranged. Therefore, it is possible to form a pattern of dot-like openings which are better in suppressing the recombination of a small number of carriers, and the power generation efficiency of the solar cell element is improved.

Here, as described above, the passivation layer forming composition is applied to a portion where the passivation layer is to be formed (portion other than the dot-shaped opening portion), and heat treatment (calcination) is performed to form a passivation layer having a desired shape. . On the other hand, a composition for forming a passivation layer is applied to the entire surface including the dot-shaped opening, and after heat treatment (baking), it is also possible to selectively remove dots by laser, photolithography or the like. a passivation layer of the opening. In addition, a portion for forming a composition for forming a passivation layer may be selectively applied by partially covering a portion of the composition for forming a passivation layer, such as a dot-shaped opening, by using a mask.

Then, as shown in (8) of FIG. 1, a silver electrode paste containing glass particles is applied to the light receiving surface by screen printing or the like. 4 is a schematic plan view showing an example of a light receiving surface of a solar cell element. As shown in FIG. 4, the light receiving surface electrode includes a light receiving surface collecting electrode 8 and a light receiving surface output extracting electrode 9. In order to secure the light receiving area, it is necessary to suppress the formation area of the light receiving surface electrodes to be small. Further, from the viewpoint of the electrical resistivity and productivity of the light-receiving surface electrode, it is preferable that the light-receiving surface current collecting electrode 8 has a width of 10 μm to 250 μm and the light-receiving surface output extraction electrode 9 has a width of 100 μm. ~2 mm. In addition, in FIG. 4, two light-receiving surface output extraction electrodes 9 are provided, but the number of the light-receiving surface output extraction electrodes 9 may be set to three from the viewpoint of the extraction efficiency (power generation efficiency) of a few carriers. Or four.

On the other hand, as shown in (8) of FIG. 1, an aluminum electrode paste containing glass powder and a silver electrode paste containing glass particles are applied on the back surface by screen printing or the like. 9 is a schematic plan view showing an example of a back surface of a solar cell element. The width of the back surface output extraction electrode 7 is not particularly limited, but the width of the back surface output extraction electrode 7 is preferably 100 μm to 10 mm from the viewpoint of the connectivity of the wiring material in the subsequent solar cell manufacturing step.

After applying the electrode paste to the light receiving surface and the back surface, after drying, the light receiving surface and the back surface are heat-treated (calcined) in the air at a temperature of about 450 ° C to 900 ° C to form a light-receiving surface. The light-receiving surface current collecting electrode 8 and the light-receiving surface output extraction electrode 9 form a back surface current collecting aluminum electrode 6 and a back surface output extraction electrode 7 on the back surface.

After the heat treatment (calcination), as shown in (9) of FIG. 1, the glass particles contained in the silver electrode paste forming the light-receiving surface electrode react with the anti-reflection film 4 on the light-receiving surface (fire through). The light receiving surface electrode (the light receiving surface collecting electrode 8 and the light receiving surface output extracting electrode 9) is electrically connected (ohmic contact) to the n ⁺ -type diffusion layer 2 . On the other hand, in the back surface where the semiconductor substrate 1 is exposed in a dot shape (the portion where the passivation layer 5 is not formed), aluminum in the aluminum electrode paste is diffused in the semiconductor substrate 1 by heat treatment (calcination), thereby forming The p ⁺ type diffusion layer 10 . By using the composition for forming a passivation layer of the present embodiment which is excellent in pattern formation property, a passivation layer having excellent passivation effect can be formed by a simple method, and a solar cell element excellent in power generation performance can be produced.

(10) to (18) of FIG. 2 are step diagrams showing a step view showing another example of a method of manufacturing a solar cell element having a passivation layer according to the present embodiment, except that etching is performed. After the n ⁺ -type diffusion layer 2 on the back surface is removed, the back surface is further flattened, and a solar cell element can be produced in the same manner as in Fig. 1 . At the time of planarization, a method of immersing the back surface of the semiconductor substrate in a mixed solution of nitric acid, hydrofluoric acid, and acetic acid or a potassium hydroxide solution may be used.

(19) to (29) of FIG. 3 are step diagrams showing a still further example of a method of manufacturing a solar cell element having a passivation layer according to the present embodiment. In this method, the steps of forming the texture structure, the n ⁺ -type diffusion layer 2, and the anti-reflection film 4 on the semiconductor substrate 1 ((19) to (24) of FIG. 3) are the same as those of the method of FIG.

After the antireflection film 4 is formed, as shown in (25) of FIG. 3, a composition for forming a passivation layer is applied, and after drying, heat treatment (baking) is performed at 300 to 900 ° C to form a passivation layer 5. An example of a formation pattern of a passivation layer in the back surface is shown in a schematic plan view in FIG. In the formation pattern of the passivation layer shown in FIG. 6, the dot-shaped opening portion is arranged on the entire surface of the back surface, and the dot-shaped opening portion is also arranged in the portion where the back surface output extraction electrode is formed in the subsequent step.

Thereafter, as shown in (26) of FIG. 3, a portion where boron or aluminum is exposed in a dot shape from the semiconductor substrate 1 (a portion where the passivation layer 5 is not formed) is diffused on the back surface, and a p ⁺ -type diffusion layer 10 is formed. . When the p ⁺ -type diffusion layer 10 is formed, in the case of diffusing boron, a method of treating at a temperature of around 1000 ° C in a gas containing boron trichloride (BCl ₃ ) can be used. However, since the gas diffusion method is performed in the same manner as in the case of using phosphorus oxychloride, the p ⁺ -type diffusion layer 10 is formed on the light receiving surface, the back surface, and the side surface of the substrate. Therefore, in order to suppress this, it is necessary to point to the point. The portion other than the opening portion is shielded, and measures such as diffusion of boron to an unnecessary portion of the p-type semiconductor substrate 1 are prevented.

Further, when the p ⁺ -type diffusion layer 10 is formed, when aluminum is diffused, a method in which an aluminum paste is applied to a dot-shaped opening portion at a temperature of 450 ° C to 900 ° C can be used. The heat treatment (calcination) is performed to diffuse aluminum from the dot-shaped opening portion to form the p ⁺ -type diffusion layer 10, and thereafter, the heat-treated layer (calcined layer) containing the aluminum paste on the p ⁺ -type diffusion layer 10 is treated with hydrochloric acid or the like. ) etching is performed.

Then, as shown in (27) of FIG. 3, the aluminum electrode 11 for back surface current collection is formed by physically vapor-depositing aluminum on the entire surface of the back surface.

Then, as shown in (28) of FIG. 3, a silver electrode paste containing glass particles is applied to the light receiving surface by screen printing or the like, and the glass is coated on the back surface by screen printing or the like. Silver electrode paste for particles. The silver electrode paste on the light receiving surface is provided in a pattern shape in combination with the shape of the light receiving surface electrode shown in FIG. 4, and the silver electrode paste on the back surface is provided in a pattern shape in combination with the shape of the back surface electrode shown in FIG.

After applying the electrode paste to the light receiving surface and the back surface, after drying, the light receiving surface and the back surface are heat-treated (calcined) in the atmosphere at a temperature of about 450 ° C to 900 ° C, as shown in FIG. 3 . As shown in (29), the light receiving surface collecting electrode 8 and the light receiving surface output extracting electrode 9 are formed on the light receiving surface, and the back surface output extraction electrode 7 is formed on the back surface. At this time, on the light receiving surface, the light receiving surface electrode is electrically connected to the n ⁺ -type diffusion layer 2, and the back surface current collecting aluminum electrode 11 formed by vapor deposition is electrically connected to the back surface output extraction electrode 7 on the back surface.

<Solar battery> The solar cell of the present embodiment includes at least one solar cell element of the present embodiment, and the wiring material is disposed on the electrode of the solar cell element. In other words, the solar cell of the present embodiment includes the solar cell element of the present embodiment and a wiring material disposed on the electrode of the solar cell element. The solar cell of the present embodiment is configured by connecting a plurality of solar cell elements via a wiring material as needed, and sealing them with a sealing material. The wiring material and the sealing material are not particularly limited, and can be appropriately selected from those generally used in the technical field. [Examples]

Hereinafter, the present invention will be specifically described by way of examples, but the invention is not limited to the examples. In addition, "%" is a quality standard unless otherwise specified.

<Example 1> (Preparation of composition 1 for passivation layer formation) 3.6627 g of pentaethoxy ruthenium (Beixing Chemical Industry Co., Ltd., structural formula: Nb(OC ₂ H ₅ ) ₅ , molecular weight: 318.2), 3.6652 g of ethyl acetate ethyl diisopropylaluminate (Kawasaki Fine Chemical Co., Ltd., trade name: ALCH), 11.1073 g of terpineol (Japan Terpene Chemical Co., Ltd., sometimes referred to as TPO), 28.6389 g of isobornylcyclohexanol (Nippon Terpene Chemical Co., Ltd., sometimes referred to as Terusolve) was mixed and mixed for 5 minutes, then 1.3497 g of pure water was added, and further kneaded for 5 minutes to prepare passivation. Composition 1 for layer formation.

(Measurement of Thickness of Passivation Layer) For a single crystal p-type ruthenium substrate having a mirror shape (50 mm square, thickness 770 μm, hereinafter referred to as ruthenium substrate A), the prepared passivation layer was formed by screen printing. Composition 1 is printed on the entire surface. Then, the crucible substrate A to which the composition 1 for passivation layer formation was applied was heated at 150 ° C for 5 minutes to evaporate the liquid medium, and dried. Thereafter, the other side of the substrate A is also printed and dried. Then, the tantalum substrate A was heat-treated (calcined) at a temperature of 700 ° C for 10 minutes, and then left to stand at room temperature (25 ° C) for cooling. The heat treatment (calcination) was carried out under the conditions of a diffusion furnace (ACCURON CQ-1200, Hitachi International Electric Co., Ltd.) under an atmospheric environment at a maximum temperature of 700 ° C for a holding time of 10 minutes.

To the obtained evaluation substrate, nine points were randomly measured from the region to which the composition for forming a passivation layer was applied using an automatic ellipsometer (Five Lab MARY-102). The average thickness of the passivation layer of the 9 points measured was 163 nm.

(Measurement of the amount of coating of the metal compound) The amount of the metal compound applied to the ruthenium substrate A is based on the mass of the composition for forming the passivation layer to be applied, the concentration of the metal compound contained in the composition for forming a passivation layer, and The area to be coated is determined by calculation. In the examples, the "metal compound coating amount" refers to the mass of the metal compound in the mass of the composition for forming a passivation layer applied per unit area (100 cm ² ) of the substrate. .

(Evaluation of Pattern Formability) When evaluating the pattern formation property of the composition for forming a passivation layer, a single-crystal p-type germanium substrate having a facet shape (50 mm square, thickness 160 μm, and the like) was used as the semiconductor substrate. Hereinafter, it is referred to as a substrate B). The ruthenium substrate B was obtained by using a substrate automatic cleaning machine (Sanyi Semiconductor Industry Co., Ltd., PV-MECH1 type) to form a single-crystal p-type ruthenium substrate having a textured surface at a temperature of 80 ° C of 30% NaOH (thickness: 180). Μm) After washing for 10 minutes, the surface was formed into a faceted shape, and then washed with pure water for 10 minutes, and dried by warm air.

In the evaluation of the pattern formation property, the prepared passivation layer-forming composition 1 was printed on the entire surface of the pattern shown in FIG. 8 except the dot or the linear opening by the screen printing method. Screen printing was carried out using a screen printing machine (NEWLONG Precision Industries, LZ-0913). Here, regarding the pattern of the dot-shaped opening for evaluation, a spot diameter (L _a ) of 200 μm and a dot interval (L _b ) of 0.886 mm and a spot diameter (L _a ) of 150 μm and a dot interval were prepared ( L _b ) is 0.664 mm, the spot diameter (L _a ) is 100 μm, and the dot spacing (L _b ) is 0.443 mm. Further, regarding the pattern of the linear opening for evaluation, a wire diameter (L _a ) of 200 μm, a line interval (L _b ) of 1.0 mm, a wire diameter (L _a ) of 150 μm, and a line interval (L) were prepared. _b ) is 1.0 mm, the wire diameter (L _a ) is 100 μm and the line spacing (L _b ) is 1.0 mm. Thereafter, the tantalum substrate to which the composition 1 for passivation layer formation was applied was heated at 150 ° C for 5 minutes to evaporate the liquid medium, followed by drying treatment. Then, the tantalum substrate B was heat-treated (calcined) at a temperature of 700 ° C for 10 minutes, and then left to cool at room temperature (25 ° C). The heat treatment (calcination) was carried out under the conditions of a diffusion furnace (ACCURON CQ-1200, Hitachi International Electric Co., Ltd.) under an atmospheric environment at a maximum temperature of 700 ° C for a holding time of 10 minutes.

Evaluation of pattern formed on the passivation layer of the substrate within the spot diameter of the dot-shaped opening portion is formed after the heat treatment (firing) (L _a) or diameter (L _a) a linear opening portion is measured. Further, the spot diameter (L _a ) or the wire diameter (L _a ) of 10 points was measured, and the average value thereof was calculated. Here, with respect to the spot diameter (L _a) immediately after the print diameter (L _a), the spot diameter (L _a) after heat treatment (calcination) or diameter (L _a) the rate of change is less than 15% by The evaluation was A, and 15% or more and less than 30% were evaluated as B, and 30% or more were evaluated as C. When the evaluation is A or B, the patterning property of the composition for forming a passivation layer is good.

(Evaluation of Cracks) In the measurement of cracks, the substrate for evaluation used in the evaluation of pattern formability was used as it is. For the evaluation substrate, an industrial inspection microscope (Olympus Co., Ltd. MX51) was used at a magnification of 50 times from a spot diameter (L _a ) of 150 μm and a dot interval (L _b ) of 0.664 mm. Three points were randomly measured in the area. Among the three points measured, those in which the crack was observed to be one point or less were evaluated as A, and those in which the substrate surface was observed to be bare were evaluated as C, and those outside the evaluation were evaluated as B. When the evaluation is A or B, the patterning property of the composition for forming a passivation layer is good.

(Measurement of Effective Life) In the measurement of the effective life, the substrate for evaluation in the measurement of the average thickness of the passivation layer was used as it is. Lifetime measuring device (SEMILAB Co., Ltd., WT-2000PVN), the effect of the obtained evaluation substrate was measured by a reflection microwave photoconductive attenuation method at room temperature (25 ° C) life. In the obtained evaluation substrate, the effective life of the region to which the composition for forming a passivation layer was applied was 1004 μs.

<Example 2> In Example 1, the blending amount was changed. Specifically, the content of each component was changed to 3.7780 g of pentaethoxy hydrazine (Beixing Chemical Industry Co., Ltd., structural formula: Nb(OC ₂ H ₅ ) ₅ , molecular weight: 318.2), and 8.9443 g of terpineol. A passivation layer-forming composition 2 was prepared in the same manner as in Example 1 except that 32.4268 g of isobornylcyclohexanol, 3.7807 g of ethyl acetate ethyl diisopropylaluminate, and 1.3922 g of pure water were used. . Then, in the same manner as in Example 1, measurement of the average thickness of the passivation layer, evaluation of pattern formation property, evaluation of cracks, and measurement of effective life were performed.

<Example 3> In Example 1, the blending amount was changed. Specifically, the content of each component was changed to 2.5175 g of pentaethoxy ruthenium (Beixing Chemical Industry Co., Ltd., structural formula: Nb(OC ₂ H ₅ ) ₅ , molecular weight: 318.2), and 12.28784 g of terpineol. A passivation layer-forming composition 3 was prepared in the same manner as in Example 1 except that 31.9857 g of isobornylcyclohexanol, 2.5192 g of ethyl acetate ethyl diisopropylaluminate, and 0.9277 g of pure water were used. . Then, in the same manner as in Example 1, the measurement of the average thickness of the passivation layer, the evaluation of the pattern formation property, the evaluation of the crack, and the measurement of the effective life of the passivation layer-forming composition 3 were carried out.

<Example 4> In Example 1, the blending amount was changed. Specifically, the content of each component was changed to 2.5184 g of pentaethoxy ruthenium (Beixing Chemical Industry Co., Ltd., structural formula: Nb(OC ₂ H ₅ ) ₅ , molecular weight: 318.2), and 9.7742 g of terpineol. A passivation layer-forming composition 4 was prepared in the same manner as in Example 1 except that 34.1519 g of isobornylcyclohexanol, 2.5202 g of ethyl acetate ethyl diisopropylaluminate, and 0.9281 g of pure water were used. . Then, in the same manner as in Example 1, the measurement of the average thickness of the passivation layer, the evaluation of the pattern formation property, the evaluation of the crack, and the measurement of the effective life of the passivation layer-forming composition 4 were carried out.

<Example 5> In Example 1, an organoaluminum compound was not used. Specifically, the content of each component was changed to 4.8926 g of pentaethoxy hydrazine (Beixing Chemical Industry Co., Ltd., structural formula: Nb(OC ₂ H ₅ ) ₅ , molecular weight: 318.2), and 10.8615 g of terpineol. A passivation layer-forming composition 4 was prepared in the same manner as in Example 1 except that 32.4981 g of isobornylcyclohexanol and 0.7934 g of pure water were used. Then, in the same manner as in Example 1, the measurement of the average thickness of the passivation layer, the evaluation of the pattern formation property, the evaluation of the crack, and the measurement of the effective life of the passivation layer-forming composition 5 were carried out.

<Reference Example 1> In the preparation of the composition for forming a passivation layer in Example 1, a compound represented by the formula (I) and an organoaluminum compound were added in a large amount. Specifically, the content of each component was changed to 10.68840 g of pentaethoxy hydrazine (Beixing Chemical Industry Co., Ltd., structural formula: Nb(OC ₂ H ₅ ) ₅ , molecular weight: 318.2), and 7.2842 g of terpineol A passivation layer-forming composition R1 was prepared in the same manner as in Example 1 except that 18.3024 g of isobornylcyclohexanol, 10.5887 g of ethyl acetate ethyl diisopropylaluminate, and 3.7180 g of pure water were used. . Then, in the same manner as in Example 1, evaluation of thixotropy of the passivation layer-forming composition R1, evaluation of pattern formation property, and evaluation of effective life were performed.

[Table 1]

[Table 2]

The compositions of the compositions for forming a passivation layer which were carried out in Examples 1 to 5 and Reference Example 1 are shown in Table 1. The results of evaluation of the average thickness of the passivation layer, the coating amount of the metal compound, the pattern formation property, the crack, and the effective life of the passivation layer of the composition for forming a passivation layer which were carried out in Examples 1 to 5 and Reference Example 1 are shown in the table. 2. The composition for forming a passivation layer formed in Examples 1 to 5 was excellent in pattern formability, and the number of cracks was small and the film quality was good.

In addition, it is understood that the effective lifetimes evaluated in Examples 1 to 5 are significantly larger than those measured in Reference Example 1, and the passivation layer-forming composition of the present embodiment is used to form an excellent passivation layer.

When the average thickness of the passivation layer of the composition for forming a passivation layer is large in the content of the compound of the formula (I) and the organoaluminum compound contained in the composition for forming a passivation layer, the thickness tends to be relatively high. The reason for this is that a sintered body of the compound of the formula (I) and the organoaluminum compound is contained in a large amount in the composition for forming a passivation layer.

Further, in the case where a compound containing both the compound of the formula (I) and the organoaluminum compound is used in the composition for forming a passivation layer, the effective life tends to be relatively high. It is considered that, since both the compound of the formula (I) and the organoaluminum compound are contained in the composition for forming a passivation layer, the metal derived from the compound of the formula (I) is formed by heat treatment (calcination). A composite oxide of aluminum forms a passivation layer or the like which is denser and has a large negative fixed charge, and the passivation effect is further improved.

Although the passivation layer remained in the tantalum substrate A and the tantalum substrate B produced in Reference Example 1, the pattern formation property and the effective life were both low. It is considered that the average thickness of the passivation layer is thicker than the desired thickness and cracks are generated as a whole, so that the surface on which the passivation layer is provided on the substrate is reduced, resulting in deterioration of pattern deformation and effective life.

All the contents disclosed in Japanese Patent Application No. 2015-199645, filed on Oct. 7, 2015, is hereby incorporated by reference. In addition, all the documents, patent applications, and technical standards described in the present specification are incorporated into the present specification in the same manner as the following, which is specific and separately describes each document, patent application, and The case where technical standards are incorporated by reference.

1‧‧‧p-type semiconductor substrate
2‧‧‧n ⁺ type diffusion layer
3‧‧‧PSG (phosphorite glass) layer
4‧‧‧Anti-reflective film
5‧‧‧ Passivation layer
6‧‧‧Aluminum electrode paste, or aluminum electrode for backside collecting, which is heat treated (calcined)
7‧‧‧Back surface output extraction electrode obtained by removing the electrode paste on the back side or heat-treating (calcining) it
8‧‧‧Electrode paste for light-receiving surface or electrode for collecting surface of light-receiving surface obtained by heat treatment (calcination)
9‧‧‧Light-receiving surface output Take-out electrode paste, or heat-treated (calcined) light-receiving surface output extraction electrode
10‧‧‧p ⁺ diffusion layer
11‧‧‧Aluminum electrode for back collector
A, B‧‧‧
L _a ‧‧‧ spot
L _b ‧‧‧ point interval

(1) to (9) of FIG. 1 are cross-sectional views schematically showing an example of a method of manufacturing a solar cell element having a passivation layer according to the present embodiment. (10) to (18) of FIG. 2 are cross-sectional views schematically showing another example of a method of manufacturing a solar cell element having a passivation layer according to the present embodiment. (19) to (29) of FIG. 3 are cross-sectional views schematically showing still another example of a method of manufacturing a solar cell element having a passivation layer according to the present embodiment. FIG. 4 is a schematic plan view showing an example of a light receiving surface of the solar battery element of the embodiment. Fig. 5 is a schematic plan view showing an example of a pattern formed on the back surface of the passivation layer of the embodiment. Fig. 6 is a schematic plan view showing another example of a pattern formed on the back surface of the passivation layer of the embodiment. Fig. 7 is a schematic plan view showing an enlarged portion A of Fig. 5; Fig. 8 is a schematic plan view showing an enlarged portion B of Fig. 5; FIG. 9 is a schematic plan view showing an example of a back surface of the solar battery element of the embodiment.

no

Claims (12)

A composition for forming a passivation layer, comprising a compound represented by the following formula (I) and water, and applied to a semiconductor substrate by a printing method to form a passivation layer having an average thickness of 200 nm or less after heat treatment, M (OR ¹ ) _m (I) In the formula (I), M represents at least one selected from the group consisting of Al, Nb, Ta, VO, Y, and Hf; and R ¹ independently represents an alkyl group or an aromatic group. The base; m represents an integer of 1 to 5. The composition for forming a passivation layer according to claim 1, which comprises the hydrolyzate of the compound represented by the above formula (I). The composition for forming a passivation layer according to the first or second aspect of the invention, further comprising a compound represented by the following formula (II), In the formula (II), R ² each independently represents an alkyl group; n represents an integer of 1 to 3; and X ² and X ³ each independently represent an oxygen atom or a methylene group; and R ³ , R ⁴ and R ⁵ are each independently The ground represents a hydrogen atom or an alkyl group. A semiconductor substrate with a passivation layer, comprising: a semiconductor substrate; and a passivation layer disposed on at least a portion of at least one surface of the semiconductor substrate, and as described in any one of claims 1 to 3 The heat-treated material of the composition for forming a passivation layer. The semiconductor substrate with a passivation layer according to claim 4, wherein the passivation layer has an average thickness of 200 nm or less. A method of producing a semiconductor substrate with a passivation layer, comprising: a composition for forming a passivation layer according to any one of claims 1 to 3, wherein at least a part of at least one surface of the semiconductor substrate is provided a step of forming a composition layer; and a step of heat-treating the composition layer to form a passivation layer. The method for producing a semiconductor substrate with a passivation layer according to claim 6, wherein the step of forming the composition for forming the passivation layer to form a composition layer includes a screen printing method. A solar cell element comprising: a semiconductor substrate having a pn junction formed by pn bonding of a p-type layer and an n-type layer; and a passivation layer provided on at least a portion of at least one surface of the semiconductor substrate, and as claimed in the patent application The heat-treated product of the composition for forming a passivation layer according to any one of the items 1 to 3, wherein the electrode is disposed on at least one of the p-type layer and the n-type layer. The solar cell element according to claim 8, wherein the passivation layer has an average thickness of 200 nm or less. A method for producing a solar cell element, comprising: at least a part of at least one surface of a semiconductor substrate having a pn junction portion having a p-type layer and an n-type layer pn-bonded, as disclosed in claims 1 to 3 The step of forming a composition layer by using the composition for forming a passivation layer according to any one of the preceding claims; the step of heat-treating the composition layer to form a passivation layer; and the p-type layer and the n-type layer The step of arranging the electrodes on at least one of the layers. The method for producing a solar cell element according to claim 10, wherein the step of forming the composition for forming the passivation layer to form a composition layer includes a screen printing method. A solar cell comprising: the solar cell element according to claim 8 or claim 9; and a wiring material disposed on the electrode of the solar cell element.