TWI609838B - Solar cell element, method of manufacturing solar cell element, and solar cell module - Google Patents

Abstract

The present invention provides a solar cell element including a semiconductor substrate having a light receiving surface, a back surface and a side surface opposite to the light receiving surface, a light receiving surface electrode disposed on the light receiving surface, and a back surface electrode disposed on the back surface; The layer is disposed on at least one of the light-receiving surface, the back surface, and the side surface, and contains a group selected from the group consisting of Nb ₂ O ₅ , Ta ₂ O ₅ , V ₂ O ₅ , Y ₂ O _{3 ,} and HfO ₂ At least one compound.

Description

Solar cell element, method of manufacturing solar cell element, and sun Battery module

The present invention relates to a solar cell element, a method of manufacturing a solar cell element, and a solar cell module.

The manufacturing steps of the conventional tantalum solar cell element will be described.

First, in order to promote the light-blocking effect and achieve high efficiency, a p-type germanium substrate having a textured structure formed on the light-receiving surface side is prepared, followed by a mixed gas atmosphere of phosphorus oxychloride (POCl ₃ ), nitrogen, and oxygen. The treatment was carried out at 800 ° C to 900 ° C for several tens of minutes to uniformly form an n-type diffusion layer. In this conventional method, since phosphorus is diffused by using a mixed gas, an n-type diffusion layer is formed not only on the surface as the light-receiving 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. In addition, the n-type diffusion layer formed on the back surface must be converted into a p ⁺ -type diffusion layer. Thus, on the whole back coat aluminum paste containing aluminum particles and a binder, and subjected to a heat treatment (calcining), whereby the n-type diffusion layer into a p ⁺ -type diffusion layer, and an aluminum electrode is formed, thereby obtaining Ohmic contact.

However, the aluminum electrode formed of the aluminum paste has a low electrical conductivity. Therefore, 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 coefficients of bismuth and aluminum differ greatly, the ruthenium substrate on which the aluminum electrode is formed generates large internal stress during heat treatment (calcination) and cooling, resulting in damage to crystal grain boundaries and crystal defects. Growth and warping.

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

In the above, a point contact method is proposed in which an aluminum paste is applied to a part of the surface of the substrate, and a p ⁺ -type diffusion layer and an aluminum electrode are partially formed (for example, refer to Japanese Patent No. 3107287). .

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 minority carrier in the surface of a portion other than the aluminum electrode. As the passivation layer for the back surface used for this purpose, an SiO ₂ film or the like has been proposed (for example, refer to Japanese Laid-Open Patent Publication No. 2004-6565). As a passivation effect obtained by forming such an SiO ₂ film, there is an effect that the unbonded bond of the germanium atoms in the surface layer portion of the back surface of the tantalum substrate is lowered, and the surface energy density of the recombination is lowered.

Further, as another method of suppressing recombination of minority carriers, there is a method of reducing the density of minority carriers by an electric field generated by a fixed charge in the passivation layer. Such a passivation effect is generally called an electric field effect, and an aluminum oxide (Al ₂ O ₃ ) film or the like has been proposed as a material having a negative fixed charge (for example, refer to Japanese Patent No. 4767110).

Such a passivation layer is usually formed by an atomic layer deposition (ALD) method or a chemical vapor deposition (CVD) method (for example, refer to the Journal of Applied Physics, 104 (2008), 113703-1~113703-7). Further, as a simple method of forming an aluminum oxide film on a semiconductor substrate, a method using a sol-gel method has been proposed (for example, refer to "Thin Solid Films", 517 (2009), 6327-6330, and "Chinese Physics". Chinese Physics Letters, 26 (2009), 088102-1~088102-4).

The method described in Journal of Applied Physics, 104 (2008), and 113703-1 to 113703-7 includes complicated manufacturing steps such as vapor deposition, and thus it may be difficult to improve productivity. In addition, it is used in the methods described in "Thin Solid Films", 517 (2009), 6327-6330, and "Chinese Physics Letters", 26 (2009), 088102-1 to 088102-4. The composition for forming a passivation layer causes a problem such as gelation over time, and it is difficult to say that the storage stability is sufficient.

The present invention has been made in view of the above conventional problems, and an object thereof is to provide a A solar cell element having excellent conversion efficiency and reduced temporal change in conversion efficiency, a simple manufacturing method thereof, and a solar cell module.

The specific means for solving the above problems are as follows.

<1> A solar cell element comprising: a semiconductor substrate having a light receiving surface; a back surface and a side surface opposite to the light receiving surface; a light receiving surface electrode disposed on the light receiving surface; a back surface electrode disposed on the back surface; and a passivation layer And disposed on at least one of the light-receiving surface, the back surface, and the side surface, and containing a group selected from the group consisting of Nb ₂ O ₅ , Ta ₂ O ₅ , V ₂ O ₅ , Y ₂ O _{3 ,} and HfO ₂ At least one compound.

The solar cell element according to the above <1>, wherein the passivation layer further contains Al ₂ O ₃ .

The solar cell element according to the above-mentioned <1>, wherein the passivation layer is a heat-treated product of a composition for forming a passivation layer.

The solar cell element according to the above-mentioned <3>, wherein the passivation layer-forming composition contains a material selected from the group consisting of Nb ₂ O ₅ , Ta ₂ O ₅ , V ₂ O ₅ , Y ₂ O ₃ , HfO ₂ and At least one compound of the group consisting of the compounds represented by the general formula (I), M(OR ¹ ) _m (I)

In the formula (I), M contains at least one metal element selected from the group consisting of niobium (Nb), tantalum (Ta), vanadium (V), yttrium (Y), and hafnium (Hf); R ^{1 is} independently The ground represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms; and m represents an integer of 0 to 5.

The solar cell element according to the above-mentioned <4>, wherein the composition for forming a passivation layer contains a group selected from the group consisting of Nb ₂ O ₅ and a compound in which M in the above formula (I) is Nb. The total content of the ruthenium compound in the composition for forming a passivation layer is 0.1% by mass to 99.9% by mass in terms of Nb ₂ O ₅ .

The solar cell element according to any one of the above aspects, wherein the composition for forming a passivation layer further contains a compound selected from the group consisting of Al ₂ O ₃ and the following formula (II). At least one aluminum compound in the group consisting of the compounds,

In the formula (II), R ² each independently represents an alkyl group having 1 to 8 carbon atoms; n represents an integer of 0 to 3; and X ² and X ³ each independently represent an oxygen atom or a methylene group; and R ³ and R ^{4 ;} And R ⁵ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

<7> The solar cell element according to the above <6>, wherein R ² in the above formula (II) is independently an alkyl group having 1 to 4 carbon atoms.

The solar cell element according to the above-mentioned <6>, wherein n in the above formula (II) is an integer of 1 to 3, and R ^{5 is} independently a hydrogen atom or a carbon number of 1 to 4. Alkyl.

The solar cell element according to any one of the above-mentioned <6>, wherein the composition for forming a passivation layer contains a compound selected from the group consisting of Al ₂ O ₃ and the compound represented by the above formula (II). At least one aluminum compound in the composition group, and the content of the aluminum compound in the passivation layer forming composition is from 0.1% by mass to 80% by mass.

The solar cell element according to any one of the above aspects, wherein the composition for forming a passivation layer further contains a liquid medium.

The solar cell element according to the above <10>, wherein the liquid medium contains a group selected from the group consisting of a hydrophobic organic solvent, an aprotic organic solvent, a terpene solvent, an ester solvent, an ether solvent, and an alcohol solvent. At least one of the groups.

The method for producing a solar cell element according to any one of the above aspects of the present invention, comprising the step of forming a light receiving surface on a light receiving surface of a semiconductor substrate a step of forming a surface electrode on the back surface, wherein the back surface is a surface opposite to the light-receiving surface of the semiconductor substrate, and a composition for forming a passivation layer is provided on at least one of the light-receiving surface, the back surface, and the side surface. a step of forming a composition layer containing the composition selected from the group consisting of Nb ₂ O ₅ , Ta ₂ O ₅ , V ₂ O ₅ , Y ₂ O ₃ , HfO ₂ and the following formula (I) At least one compound of the group consisting of the compounds; and a step of heat-treating the above-mentioned composition layer to form a passivation layer; M(OR ¹ ) _m (I)

In the formula (I), M contains at least one metal element selected from the group consisting of Nb, Ta, V, Y and Hf; and R ¹ independently represents an alkyl group having 1 to 8 carbon atoms or a carbon number of 6~ 14 aryl; m represents an integer from 0 to 5.

The method for producing a solar cell element according to the above <12>, wherein the composition for forming a passivation layer further contains a group selected from the group consisting of Al ₂ O ₃ and a compound represented by the following formula (II). At least one aluminum compound in the group,

In the formula (II), R ² each independently represents an alkyl group having 1 to 8 carbon atoms; n represents an integer of 0 to 3; and X ² and X ³ each independently represent an oxygen atom or a methylene group; and R ³ and R ^{4 ;} And R ⁵ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

<14> A solar cell element as described in <12> or <13> above The manufacturing method, wherein the temperature of the above heat treatment is 400 ° C or higher.

The method for producing a solar cell element according to any one of the above aspects, wherein the step of forming the composition layer comprises: applying the passivation layer by a screen printing method or an inkjet method. A composition for formation.

The solar cell module of any one of the above-mentioned <1> to <11>, and the wiring material arrange|positioned on the electrode of the said solar cell element.

According to the present invention, it is possible to provide a solar cell element which has excellent conversion efficiency and which has reduced temporal deterioration of conversion efficiency, a simple manufacturing method thereof, and a solar cell module.

1‧‧‧p-type semiconductor substrate

2‧‧‧n ⁺ type diffusion layer

3‧‧‧Anti-reflective film

4‧‧‧p ⁺ diffusion layer

5‧‧‧Back electrode

6‧‧‧ Passivation layer

7‧‧‧Lighted surface electrode

8‧‧‧ Heat treated

9‧‧‧ openings

10‧‧‧ area

101, 111‧‧‧矽 substrate

102, 112‧‧‧ diffusion layer

103, 113‧‧‧Lighted anti-reflection film

104‧‧‧BSF layer

105, 115‧‧‧ first electrode

106‧‧‧2nd electrode

107‧‧‧passivation film

114‧‧‧p ⁺ layer

116‧‧‧electrode

OA‧‧‧ openings

FIG. 1 is a cross-sectional view schematically showing an example of a method of manufacturing a solar cell element having a passivation layer according to the embodiment.

Fig. 2 is a cross-sectional view schematically showing another example of a method of manufacturing a solar cell element having a passivation layer according to the embodiment.

3 is a plan view schematically showing a printed pattern of a composition for forming a passivation layer and a printed pattern of an aluminum electrode in the examples.

Fig. 4 is a plan view schematically showing a printing pattern of a silver electrode in the embodiment.

Fig. 5 is a cross-sectional view showing the structure of a double-sided electrode type solar cell element.

Fig. 6 is a cross-sectional view showing a first configuration example of a solar battery element according to a reference embodiment; Surface map.

Fig. 7 is a cross-sectional view showing a second configuration example of the solar battery element of the embodiment.

8 is a cross-sectional view showing a third configuration example of the solar battery element according to the embodiment.

FIG. 9 is a cross-sectional view showing a fourth configuration example of the solar battery element according to the embodiment.

Fig. 10 is a cross-sectional view showing another configuration example of the solar battery element of the reference embodiment.

In the present specification, the term "step" means not only an independent step, but even in the case where 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, in this specification, the numerical range represented by "~" is a range which contains the numerical value of the before and after "~" as a minimum and maximum. Further, in the present specification, 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, it means the plurality of substances present in the composition. Total measurement. In addition, in this specification, the term "layer" includes a configuration of a shape formed on a part of the entire surface, in addition to a configuration of a shape formed on the entire surface when viewed in a plan view.

<Solar battery component>

The solar cell element of the present invention includes a semiconductor substrate having a light receiving surface, a back surface and a side surface opposite to the light receiving surface, a light receiving surface electrode disposed on the light receiving surface, a back surface electrode disposed on the back surface, and a passivation layer. And disposed on at least one surface of the light-receiving surface, the back surface, and the side surface, and containing a group selected from the group consisting of Nb ₂ O ₅ , Ta ₂ O ₅ , V ₂ O ₅ , Y ₂ O _{3 ,} and HfO ₂ At least one compound (hereinafter also referred to as "specific metal oxide", the metal element contained in each specific metal oxide is also referred to as "specific metal element"). The above solar cell element may have other components as needed.

The solar cell element having a passivation layer containing a specific metal oxide on at least one of the light-receiving surface, the back surface, and the side surface of the semiconductor substrate is excellent in conversion efficiency, and the temporal deterioration of conversion efficiency is suppressed. The reason for this is considered to be that the passivation layer contains a specific metal oxide and exhibits an excellent passivation effect, and the life of the carrier in the semiconductor substrate is increased, so that high efficiency can be achieved. Further, it is considered that by having the passivation layer containing the specific metal oxide described above, the passivation effect can be maintained, and the deterioration of the conversion efficiency with time can be suppressed. Here, the temporal deterioration of the characteristics of the solar cell can be evaluated by the characteristics of the solar cell after standing for a predetermined period of time in the constant temperature and humidity chamber.

The reason why the passivation layer containing a specific metal oxide on at least one of the light-receiving surface, the back surface, and the side surface of the semiconductor substrate has an excellent passivation effect is considered as follows. That is, it is considered that by providing a passivation layer containing a specific metal oxide on the surface of the semiconductor substrate, a specific metal element or a defect of an oxygen atom in a specific metal oxide or the like causes a fixed charge in the vicinity of the interface with the semiconductor substrate. . It is considered that the fixed electric charge generates an electric field in the vicinity of the interface of the semiconductor substrate, thereby causing band bending and lowering the concentration of a minority carrier. The result can be recognized Since the recombination speed of the carrier on the interface is suppressed, an excellent passivation effect is exerted.

The fixed charge possessed by a particular metal oxide can be evaluated using Capacitance Voltage Measurement (CV). When the surface energy density of the passivation layer formed by heat-treating the composition for forming a passivation layer to be described later is evaluated by the CV method, it may become larger as compared with the case of the passivation layer formed by the ALD method or the CVD method. Value. However, the passivation layer of the solar cell element of the present invention has a large electric field effect and a small concentration of carriers, and the surface life τ _s becomes large. Therefore, the surface energy density is relatively unproblematic.

In the present specification, the passivation effect of the semiconductor substrate can be evaluated by using a device such as WT-2000PVN of the company Semilab Co., Ltd., by forming a passivation layer by a reflective microwave conduction attenuation method. The effective lifetime of a minority carrier in the semiconductor substrate is measured.

Here, the effective lifetime τ is expressed by the following formula (A) by the bulk lifetime τ _b inside the semiconductor substrate and the surface lifetime τ _{s of the} surface of the semiconductor substrate. When the surface energy 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 body life τ _{b is} also long, and the effective life τ is 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)

In addition, the longer the effective lifetime τ, the slower the recombination speed of a minority carrier. In addition, the solar cell is constructed by using a semiconductor substrate having a long effective life. The conversion efficiency is improved.

The solar cell element includes a semiconductor substrate having a light receiving surface and a back surface opposite to the light receiving surface. The semiconductor substrate is not particularly limited, and may be appropriately selected from those generally used depending on the purpose. Examples of the semiconductor substrate include those in which p-type impurities or n-type impurities are 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 a surface on which a passivation layer is formed (that is, at least one of a light-receiving surface, a back surface, and a side surface) 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 as a p-type diffusion layer or a p ⁺ -type diffusion layer.

In the semiconductor substrate, it is preferable to pn-bond the p-type layer and the n-type layer. That is, when the semiconductor substrate is a p-type semiconductor substrate, it is preferable to form an n-type layer on the light receiving surface or the back surface of the semiconductor substrate. When the semiconductor substrate is an n-type semiconductor substrate, it is preferable to form a p-type layer on the light-receiving surface or the back surface of the semiconductor substrate. The method of forming the p-type layer or the n-type layer on the semiconductor substrate is not particularly limited, and can be appropriately selected from the methods generally used.

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 shape and size of the semiconductor substrate are not limited, and for example, a square having a side of 125 mm to 156 mm can be set.

The solar cell element of the present invention has a light receiving surface disposed on a light receiving surface The electrode and the back surface electrode disposed on the back surface of the semiconductor substrate opposite to the light receiving surface. The light-receiving surface electrode has a function of collecting current on the light-receiving surface of the semiconductor substrate, for example. The back electrode has a function of outputting a current to the outside, for example.

The material of the light-receiving electrode is not particularly limited, and examples thereof include silver, copper, and aluminum. The thickness of the light-receiving surface electrode is not particularly limited, and is preferably from 0.1 μm to 50 μm from the viewpoint of conductivity and homogeneity.

The material of the back electrode is not particularly limited, and examples thereof include silver, copper, and aluminum. The back electrode is preferably made of aluminum from the viewpoint of forming a back electrode and diffusing aluminum atoms into the semiconductor substrate to form a p ⁺ -type diffusion layer. The thickness of the back surface electrode is not particularly limited, and is preferably from 0.1 μm to 50 μm from the viewpoint of conductivity and warpage of the substrate.

The light-receiving electrode and the back electrode can be produced by a usual method. For example, the light-receiving surface electrode and the back surface electrode can be produced by applying a paste for forming an electrode such as a silver paste, an aluminum paste or a copper paste to a desired region of the semiconductor substrate, and heat-treating (calcining) as necessary.

The solar cell element of the present invention has a passivation layer containing a specific metal oxide on at least one of a light receiving surface, a back surface, and a side surface of the semiconductor substrate. Further, the passivation layer may contain Al ₂ O ₃ . The passivation layer may be provided on a part or the entire surface of at least one of the above surfaces, and is preferably provided in a region other than the electrode. Further, the electrode may be formed by having an overlapping portion with the passivation layer.

The average thickness of the passivation layer formed on the semiconductor substrate is not particularly limited and may be appropriately selected depending on the purpose. For example, in terms of passivation effect, blunt The average thickness of the layer is preferably from 5 nm to 50 μm, more preferably from 10 nm to 30 μm, and even more preferably from 15 nm to 20 μm. Here, the average thickness of the passivation layer is measured by a conventional method using an interferometric film thickness meter (for example, a F20 film thickness measurement system manufactured by Filmetrics Co., Ltd.), and the arithmetic mean value thereof is used. The form is calculated.

The content of the specific metal oxide contained in the passivation layer is preferably from 0.1% by mass to 100% by mass, more preferably from 1% by mass to 100% by mass, even more preferably 10 from the viewpoint of obtaining a sufficient passivation effect. Mass%~100% by mass.

The content of the specific metal oxide contained in the passivation layer can be measured by the following method. The ratio of inorganic substances is calculated by thermogravimetric analysis using atomic absorption spectrometry, inductively coupled plasma luminescence spectrometry, thermogravimetric analysis, X-ray photoelectron spectroscopy, and the like. Then, the ratio of the compound of the specific metal element in the inorganic substance is calculated by atomic absorption spectrometry, inductively coupled plasma luminescence spectrometry, or the like, and the specific metal element is calculated by X-ray photoelectric spectroscopy, X-ray absorption spectroscopy, or the like. The ratio of a particular metal oxide in a compound.

The passivation layer may also contain other inorganic oxides other than the specific metal oxide. The other inorganic oxide is preferably a compound having a fixed charge, and specific examples thereof include alumina, cerium oxide, titanium oxide, gallium oxide, zirconium oxide, boron oxide, indium oxide, phosphorus oxide, zinc oxide, cerium oxide, cerium oxide, and the like. Cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, etc., in terms of high passivation effect, preferably selected At least one of the group consisting of free cerium oxide, titanium oxide, zirconium oxide, cerium oxide and aluminum oxide, more preferably at least containing aluminum oxide.

The content of the other inorganic oxide in the passivation layer is preferably 80% by mass or less, and more preferably 60% by mass or less. The content of the other inorganic oxide contained in the passivation layer can be measured in the same manner as the method for measuring the content of the specific metal oxide described above.

The density of the passivation layer is preferably from 1.0 g/cm ³ to 8.0 g/cm ³ , more preferably from 2.0 g/cm ³ to 6.0 g/cm ³ , from the viewpoint of stability over time of the passivation effect, and further preferably 3.0 g/cm ³ ~ 5.0 g/cm ³ .

The density of the passivation layer is calculated from the area and thickness of the passivation layer and the quality of the passivation layer. Specifically, the density of the passivation layer is measured using a pressure suspension method or a temperature suspension method.

<Composition for forming a passivation layer>

The passivation layer of the solar cell element of the present invention is preferably a heat-treated product of a composition for forming a passivation layer. The passivation layer-forming composition is not particularly limited as long as it can be formed by a heat treatment (calcination) to form a passivation layer containing a specific metal oxide, and may contain a specific metal oxide itself or a specific metal oxide. Precursor. A particular metal oxide and its precursor are also referred to as a particular metal compound.

The passivation layer forming composition preferably contains a specific metal oxide (Nb ₂ O ₅ , Ta ₂ O ₅ , V ₂ O ₅ , Y ₂ O _{3 ,} and HfO ₂ ) selected from the viewpoints of high passivation effect. And at least one compound of the group consisting of a compound represented by the following formula (I) (hereinafter also referred to as a compound of the formula (I)) as the above-mentioned precursor of the specific metal oxide.

M(OR ¹ ) _m (I)

In the formula (I), M contains at least one metal element selected from the group consisting of Nb, Ta, V, Y and Hf. R ¹ each independently represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms. m represents an integer from 0 to 5.

In the general formula (I), R ¹ each independently represents an alkyl having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms, preferably an alkyl group having 1 to 8 carbon atoms, more preferably 1 to 4 alkyl groups. The alkyl group represented by R ¹ may be linear or branched. Alkyl group represented by R ¹ include specifically: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, hexyl, octyl, 2-ethyl Heji and so on. 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 a halogen atom, an amine group, a hydroxyl group, a carboxyl group, a thiol group or a nitro group. The substituent of the aryl group may, for example, be a halogen atom, a methyl group, an ethyl group, an isopropyl group, an amine group, a hydroxyl group, a carboxyl group, a decyl group or a nitro group.

Among them, from the viewpoint of storage stability and 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 0 to 5. From the viewpoint of storage stability, m is preferably an integer of 1 to 5.

From the viewpoint of the passivation effect, the compound represented by the formula (I) preferably has at least one metal element selected from the group consisting of Nb, Ta and Y. Further, from the viewpoint of making the fixed charge density of the passivation layer negative, M preferably contains at least one metal element selected from the group consisting of Nb, Ta, V, and Hf, and more preferably contains Nb selected from In a group consisting of Ta, VO, and Hf At least one.

Further, from the viewpoint of storage stability and passivation effect, the compound represented by the formula (I) is more preferably an unsubstituted alkyl group having R ¹ of 1 to 4 carbon atoms, from the viewpoint of storage stability. Preferably, m is an integer from 1 to 5.

The state of the compound represented by the formula (I) may be either a solid or a liquid. The compound represented by the formula (I) is preferably at room temperature from the viewpoint of the storage stability of the composition for forming a passivation layer and the mixing property in the case of using the compound represented by the following formula (II). Liquid at 25 ° C).

Examples of the compound represented by the formula (I) include hydrazine, methanol hydrazine, hydrazine ethoxide, hydrazine isopropoxide, hydrazine n-propoxide, hydrazine n-butoxide, hydrazine tert-butoxide, hydrazine isobutoxide, hydrazine hydride, and ethanol. Barium, strontium, barium isopropoxide, barium n-propoxide, barium n-butoxide, barium tert-butoxide, barium isobutoxide, barium, methanol, barium ethoxide, barium isopropoxide, barium n-propoxide, n-butyl Alcohol, barium butanol, barium isobutoxide, vanadium, vanadium oxide, vanadium oxide, vanadium isopropoxide, vanadium volate, n-butanol vanadium oxide, vanadium butoxide, vanadium Butanol oxide vanadium, ruthenium, methanol oxime, ruthenium ethoxide, bismuth isopropoxide, ruthenium n-propoxide, ruthenium n-butoxide, hydrazine tert-butoxide, hydrazine isobutanol, etc., among which ethanol hydrazine and n-propyl acrylate are preferred. Alcohol oxime, n-butanol oxime, ethanol oxime, n-propanol oxime, n-butanol oxime, isopropanol oxime and n-butanol oxime. From the viewpoint of obtaining a negative fixed charge density, preferably ruthenium ethoxide, ruthenium n-propoxide, ruthenium n-butoxide, ruthenium ethoxide, ruthenium n-propoxide, ruthenium n-butoxide, vanadium oxide, n-propanol vanadium oxide , n-butanol oxide vanadium, ethanol oxime, n-propanol oxime and n-butanol oxime.

Further, the compound represented by the formula (I) may be used as a preparation, or Use a commercial product. Commercially available products include, for example, pentamethoxy hydrazine, pentaethoxy hydrazine, pentaisopropoxy fluorene, penta-n-propoxy fluorene, penta-isobutoxy fluorene, and five. n-Butoxy fluorene, penta-butoxy fluorene, pentamethoxy fluorene, pentaethoxy hydrazine, pentaisopropoxy fluorene, penta-n-propoxy fluorene, penta-isobutoxy fluorene, five-positive Butoxy oxime, penta-second butoxy ruthenium, penta-t-butoxy ruthenium, vanadium oxyhydroxide (V), triethoxy vanadium oxide (V), triisopropanol vanadium oxide (V) , tri-n-propanol vanadium oxide (V), triisobutanol vanadium oxide (V), tri-n-butanol vanadium oxide (V), tri-second butanol vanadium oxide (V), tri-tert-butanol oxidation Vanadium (V), triisopropoxy ruthenium, tri-n-butoxy ruthenium, tetramethoxy ruthenium, tetraethoxy ruthenium, tetraisopropoxy ruthenium, tetra-t-butoxy ruthenium; Beixing Chemical Industry Co., Ltd.'s pentaethoxy oxime, pentaethoxy hydrazine, pentabutoxy fluorene, n-butanol oxime, t-butanol oxime; Nichia Chemicals Co., Ltd. oxytriethanol vanadium, oxy three Vanadium n-propoxide, vanadium oxy-n-butoxide, vanadium oxytriisobutoxide, oxy-three Second butanol vanadium and the like.

In the case of preparing the compound of the formula (I) (in the case of m in the case of 1 to 5), the preparation method may be carried out by a known method such as the specific metal element (M) contained in the compound of the formula (I). A method in which a halide and an alcohol are reacted in the presence of an inactive organic solvent, and an ammonia or an amine compound is added in order to obtain a halogen (Japanese Patent Laid-Open Publication No. SHO63-227593A and JP-A No. 3-291247).

The content of the compound of the formula (I) contained in the composition for forming a passivation layer can be appropriately selected as needed. From the viewpoint of the storage stability and the passivation effect, the content of the compound of the formula (I) in the composition for forming a passivation layer can be set to 0.1% by mass to 80% by mass, preferably 0.5% by mass to 70% by mass. More preferably 1% by mass ~60% by mass, and further preferably 1% by mass to 50% by mass.

When the composition for forming a passivation layer contains a compound of m=1 to 5 (hereinafter also referred to as a specific metal alkoxide compound) in the compound of the formula (I), a chelate may be added to the above metal alkoxide compound. Reagent (chelating agent). The chelating agent can be exemplified by Ethylene Diamine Tetraacetic Acid (EDTA), bipyridine, heme, naphthyridine, benzimidazolylmethylamine, oxalic acid, and propylene. Dicarboxylic acids such as acid, succinic acid, glutaric acid, adipic acid, tartaric acid, maleic acid, phthalic acid, β-diketone compounds, β-ketoester compounds, and malonic acid diesters.

The chelating agent can be specifically exemplified by acetamidine acetone, 3-methyl-2,4-pentanedione, 2,3-pentanedione, 3-ethyl-2,4-pentanedione, 3-butyl- 2,4-pentanedione, 2,2,6,6-tetramethyl-3,5-heptanedione, 2,6-dimethyl-3,5-heptanedione, 6-methyl-2 , β-diketone compound such as 4-heptanedione; methyl acetate methyl acetate, ethyl acetate ethyl acetate, propyl acetate, isobutyl acetate, butyl acetate, butyl acetate Ester, amyl acetate, isoamyl acetate, hexyl acetate, n-octyl acetate, heptyl acetate, 3-pentyl acetate, 2-ethyl decyl heptanoate Ester, ethyl 2-butylacetate, ethyl 4,4-dimethyl-3-oxopentanoate, ethyl 4-methyl-3-oxopentanoate, 2-ethylacetamidineacetic acid Ethyl ethyl ester, ethyl hexylacetate ethyl acetate, methyl 4-methyl-3-oxopentanoate, isopropyl acetate, ethyl 3-oxohexanoate, ethyl 3-oxopentanoate, 3 - methyl oxovalerate, methyl 3-oxohexanoate, ethyl 2-methylacetate, ethyl 3-oxoheptanoate, methyl 3-oxoheptanoate, 4,4-di a β-ketoester compound such as methyl-3-oxopentanoate; dimethyl malonate, Diethyl malonate, dipropyl malonate, diisopropyl malonate, Dibutyl malonate, di-tert-butyl malonate, dihexyl malonate, tert-butylethyl malonate, diethyl methylmalonate, diethyl malonate Ester, diethyl isopropyl malonate, diethyl butyl malonate, diethyl second butyl malonate, diethyl isobutyl malonate, 1-methylbutyl propylene A malonic acid diester such as diethyl acid.

In the case where the specific metal alkoxide compound has a chelate structure, the presence of the above chelate structure can be confirmed by an analysis method generally used. For example, it can be confirmed using an infrared spectroscopic spectrum, a nuclear magnetic resonance spectrum, or a melting point.

The specific metal alkoxide compound can also be used in a state of hydrolysis and dehydration polycondensation. In order to carry out hydrolysis and dehydration polycondensation, the reaction may be carried out in the presence of water and a catalyst, and water and a catalyst may be distilled off after hydrolysis and dehydration condensation. The catalyst can be exemplified by inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, boric acid, phosphoric acid, hydrofluoric acid; and formic acid, acetic acid, propionic acid, butyric acid, oleic acid, linoleic acid, and salicylate. Organic acids such as acid, benzoic acid, phthalic acid, oxalic acid, lactic acid, and succinic acid. Further, a base such as ammonia or an amine may be added as a catalyst.

The composition for forming a passivation layer may also contain other precursors of a specific metal oxide other than the compound of the formula (I). The other precursor of the specific metal oxide is not particularly limited as long as it is a specific metal oxide by heat treatment (calcination). Specifically, other precursors of a specific metal oxide can be exemplified by citric acid, cerium chloride, cerium oxide, cerium carbide, cerium hydroxide, ceric acid, cerium chloride, cerium pentachloride, vanadium oxychloride, Vanadium pentoxide, vanadium oxybis(2,4-pentanedionate), cerium chloride, cerium nitrate, cerium oxalate, cerium stearate, cerium carbonate, cerium naphthenate, cerium propionate, cerium nitrate, Barium octoate, barium chloride, tetrakis(2,4-pentanedionate), and the like.

The composition for forming a passivation layer may further contain at least one selected from other inorganic oxides other than the specific metal compound and a precursor thereof (hereinafter also referred to as other inorganic compounds). Other inorganic compounds include alumina, cerium oxide, titanium oxide, gallium oxide, zirconium oxide, boron oxide, indium oxide, phosphorus oxide, zinc oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide. , cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide and precursors of such oxides. The inorganic compound is preferably selected from the group consisting of cerium oxide, titanium oxide, zirconium oxide, cerium oxide, aluminum oxide, and precursors of the oxides from the viewpoints of high passivation effect and suppression of deterioration over time. At least one of them is more preferably at least one selected from the group consisting of alumina and its precursor, from the viewpoint of further improving the passivation effect. The precursor of alumina is preferably a compound represented by the following formula (II).

In the formula, R ² each independently represents an alkyl group having 1 to 8 carbon atoms. n represents an integer from 0 to 3. X ² and X ³ each independently represent an oxygen atom or a methylene group. R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Here, when there are a plurality of R ² to R ⁵ , X ² and X ³ , a plurality of groups represented by the same symbol may be the same or different.

From the viewpoint of further improving the passivation effect, it is preferred to contain at least one selected from the group consisting of Al ₂ O ₃ and a compound represented by the following formula (II) (hereinafter also referred to as an organoaluminum compound). Aluminum compound.

In the formula (II), R ² each independently represents an alkyl group having 1 to 8 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms. The alkyl group represented by R ² may be linear or branched. Alkyl group represented by R ² include specifically: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, hexyl, octyl, 2-ethyl Heji and so on. In view of the storage stability and the 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 0 to 3. From the viewpoint of storage stability, n is preferably an integer of 1 to 3, more preferably 1 or 3. 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 having 1 to 8 carbon atoms. The alkyl group represented by R ³ , R ⁴ and R ⁵ may be linear or branched. The alkyl group represented by R ³ , R ⁴ and R ⁵ may have a substituent or may be unsubstituted, and is preferably unsubstituted. The alkyl group represented by R ³ , R ⁴ and R ⁵ is an alkyl group having 1 to 8 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group represented by R ³ , R ⁴ and R ⁵ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a second butyl group, a tert-butyl group, a hexyl group, and a octyl group. Base, 2-ethylhexyl and the like.

In view of the storage stability and the passivation effect, R ³ and R ⁴ in the formula (II) are preferably independently a hydrogen atom or an unsubstituted alkyl group having 1 to 8 carbon atoms, more preferably Preferably, it is a hydrogen atom or an unsubstituted alkyl group having 1 to 4 carbon atoms.

Further, R ⁵ in the formula (II) is preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 8 carbon atoms, more preferably a hydrogen atom or a carbon number, from the viewpoint of storage stability and passivation effect. 1 to 4 unsubstituted alkyl groups.

From the viewpoint of storage stability, the compound represented by the formula (II) is preferably an integer in which n is from 1 to 3, and each of R ^{5 is} independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

The compound represented by the formula (II) is preferably at least one selected from the group consisting of: n is 0, and R ^{2 is} independently a carbon number from the viewpoint of storage stability and passivation effect. a compound of 1 to 4 alkyl groups; and n is 1 to 3, R ^{2 is} independently an alkyl group having 1 to 4 carbon atoms, at least one of X ² and X ³ is an oxygen atom, and R ³ and R ⁴ are each independently The ground is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ⁵ is a compound having a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

More preferably, the compound represented by the formula (II) is at least one selected from the group consisting of: n is 0, and R ² is a compound having an unsubstituted alkyl group having 1 to 4 carbon atoms; n is 1 to 3, R ² is an unsubstituted alkyl group having 1 to 4 carbon atoms, at least one of X ² and X ³ is an oxygen atom, and R ³ or R ⁴ bonded to the above oxygen atom is a carbon number of 1. The alkyl group of ~4, when X ² or X ³ is a methylene group, is a compound in which R ³ or R ⁴ of the above methylene group is a hydrogen atom and R ⁵ is a hydrogen atom.

Specific examples of the organoaluminum compound (trialkoxide aluminum) represented by the formula (II) and wherein n is 0 include trimethoxy aluminum, triethoxy aluminum, triisopropoxy aluminum, and tri-2-butene. Aluminium oxyaluminum, mono-2-butoxydisisopropoxyaluminum, tri-t-butoxyaluminum, tri-n-butoxyaluminum, and the like.

Further, the organoaluminum compound represented by the formula (II) and having n to 1 to 3 may specifically be exemplified by ethyl ethylacetate diisopropylate [(ethylacetamidineacetic acid) isopropoxyl Aluminium], tris(ethylacetoacetato)aluminum, etc.

Further, the organoaluminum compound represented by the formula (II) and having n to 1 to 3 can be used as a preparation, and a commercially available product can also be used. Commercially available products include, for example, trade names ALCH, ALCH-50F, ALCH-75, ALCH-TR, and ALCH-TR-20 of Kawasaki Seika Co., Ltd.

The organoaluminum compound is preferably a chelate aluminum compound of n = 1 to 3 in the formula (II). The chelate aluminum compound has a chelate aluminum structure in addition to the aluminum alkoxide structure of n=0.

In the case where the aluminum alkoxide having n = 0 in the formula (II) is contained in the composition for forming a passivation layer, it is preferred that the chelating agent (chelating agent) is contained in the composition for forming a passivation layer. The chelating agent may, for example, be a chelating agent as described above, and is preferably a compound having a specific structure of two carbonyl groups such as a β-diketone compound, a β-ketoester compound or a malonic acid diester.

The alkoxide structure of the organoaluminum compound and the presence of a chelate structure are available The analytical method usually used is confirmed. For example, it can be confirmed using an infrared spectroscopic spectrum, a nuclear magnetic resonance spectrum, a melting point, or the like.

It is considered that the thermal stability and chemical stability of the organoaluminum compound are improved by using aluminum alkoxide and a chelating agent in combination or by using a chelated organoaluminum compound, and the transition to alumina during heat treatment is suppressed. As a result, it is considered that the transition to the alumina in the thermodynamically stable crystalline state is suppressed, and the alumina in an amorphous state is easily formed.

Further, the state of the metal oxide in the formed passivation layer can be confirmed by measuring X-ray diffraction (XRD). For example, it can be confirmed as an amorphous structure according to the fact that XRD does not show a specific reflection pattern. When the composition for forming a passivation layer contains an organoaluminum compound, the alumina in the passivation layer obtained by heat treatment (calcination) is preferably an amorphous structure. When the alumina is in an amorphous state, aluminum defects or oxygen defects are likely to occur, and a fixed charge is easily generated in the passivation layer, and a large passivation effect is easily obtained.

The organoaluminum compound represented by the formula (II) and having n to 1 to 3 can be produced by mixing a trialkoxyaluminum having n of 0 with a compound having a specific structure of two carbonyl groups. The compound having a specific structure of two carbonyl groups may, for example, be the above chelating agent. Further, a commercially available chelated aluminum compound can also be used. When the above trialkoxyaluminum is mixed with a chelating agent, at least a part of the alkoxide group of the trialkoxyaluminum is replaced with a compound having a specific structure to form a chelate aluminum structure. At this time, a solvent may be present as needed, and heat treatment or addition of a catalyst may be performed. By hydrolyzing and polymerizing an organoaluminum compound by replacing at least a portion of the aluminum alkoxide structure with a chelated aluminum structure The stability is improved, and the storage stability of the composition for forming a passivation layer containing the same is further improved.

In the case where the organoaluminum compound has a chelate aluminum structure, there is no particular limitation as long as the number of the chelate aluminum structures is from 1 to 3. Among them, from the viewpoint of storage stability, it is preferably 1 or 3, more preferably 1. The number of the chelate aluminum structure can be controlled, for example, by appropriately adjusting the mixing ratio of the above trialkoxyaluminum and the compound having a specific structure of the above two carbonyl groups. Further, a compound having a desired structure may be appropriately selected from commercially available chelate aluminum compounds.

In the compound represented by the formula (II), in terms of the passivation effect and compatibility with a solvent contained as necessary, specifically, it is preferred to use a diisopropyl alcohol selected from ethyl acetamidine acetate. At least one of the group consisting of aluminum and aluminum triisopropoxide is more preferably ethyl acetoacetate aluminum diisopropylate.

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

In the case where the composition for forming a passivation layer contains at least one aluminum compound selected from the group consisting of Al ₂ O ₃ and the compound represented by the above formula (II), the content of the aluminum compound is preferably 0.1% by mass to 80% by mass, more preferably 10% by mass to 70% by mass. From the viewpoint of further improving the passivation effect, the content of the aluminum compound is preferably from 0.1% by mass to 99.9 by mass based on the total amount of the metal compound, the compound represented by the above formula (II), and the total amount of Al ₂ O ₃ . % is more preferably 1% by mass to 99% by mass, and further preferably 2% by mass to 70% by mass.

In the case where the composition for forming a passivation layer contains an aluminum compound, the composition of the metal oxide in the passivation layer obtained by heat-treating the composition for forming a passivation layer may be, for example, Nb ₂ O ₅ -Al ₂ O ₃ or Al ₂ O. _a binary composite oxide such as ₃ -Ta ₂ O ₅ , Al ₂ O ₃ -Y ₂ O ₃ , Al ₂ O ₃ -V ₂ O ₅ , Al ₂ O ₃ -HfO ₂ ; and Nb ₂ O ₅ -Al ₂ O ₃ -Ta ₂ O ₅ , Al ₂ O ₃ -Y ₂ O ₃ -Ta ₂ O ₅ , Nb ₂ O ₅ -Al ₂ O ₃ -V ₂ O ₅ , Al ₂ O ₃ -HfO ₂ -Ta ₂ O ₅ A ternary composite oxide.

The composition for forming a passivation layer is preferably at least one antimony compound containing a group selected from the group consisting of Nb ₂ O ₅ and a compound in which M in the above formula (I) is Nb. When the composition for forming a passivation layer contains the above-mentioned ruthenium compound, the content of the ruthenium compound in the composition for forming a passivation layer is preferably 0.1% by mass to 99.9% by mass in terms of Nb ₂ O ₅ , more preferably It is preferably from 1% by mass to 99% by mass, and more preferably from 30% by mass to 85% by mass.

In the case where the composition for forming a passivation layer contains a ruthenium compound, the composition of the metal oxide in the passivation layer obtained by heat-treating the composition for forming a passivation layer may be, for example, Nb ₂ O ₅ -Al ₂ O ₃ or Nb ₂ O. _{5 -Ta 2 O 5, Nb 2} O 5 -Y 2 O 3, Nb 2 O 5 -V 2 O 5, Nb 2 O 5 -HfO 2 binary composite oxide and the like; and Nb ₂ O ₅ -Al ₂ O ₃ -Ta ₂ O ₅ , Nb ₂ O ₅ -Y ₂ O ₃ -Ta ₂ O ₅ , Nb ₂ O ₅ -Al ₂ O ₃ -V ₂ O ₅ , Nb ₂ O ₅ -HfO ₂ -Ta ₂ O ₅ A ternary composite oxide.

The composition for forming a passivation layer is applied to a semiconductor substrate to form a composition layer of a desired shape, and the composition layer is subjected to heat treatment (calcination), whereby a passivation layer having an excellent passivation effect can be formed. In addition, the above passivation layer is formed The occurrence of a problem such as gelation of the composition is suppressed, and the storage stability over time is excellent.

(liquid medium)

The composition for forming a passivation layer preferably contains a liquid medium (solvent or dispersion medium). When the composition for forming a passivation layer contains a liquid medium, the viscosity is adjusted more easily, and the impartability is further improved, and a uniform heat treatment layer can be formed. The liquid medium is not particularly limited as long as it can dissolve or disperse a specific metal compound, and can be appropriately selected as necessary. 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-amyl ketone. Methyl n-hexyl ketone, diethyl ketone, dipropyl ketone, 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 dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, two 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, triethyl Diol 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 Ether, tetraethylene glycol dimethyl ether, tetraethylene glycol Ether, tetraethylene glycol methyl ethyl ether, tetraethylene glycol methyl n-butyl ether, tetraethylene Alcohol di-n-butyl ether, tetraethylene glycol methyl n-hexyl ether, tetraethylene glycol di-n-butyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n-propyl ether, propylene glycol dibutyl ether, dipropylene glycol dimethyl ether , dipropylene glycol diethyl ether, dipropylene glycol methyl ethyl ether, dipropylene glycol 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, four Ether solvent such as propylene glycol methyl ethyl ether, tetrapropylene glycol methyl n-butyl ether, tetrapropylene glycol di-n-butyl ether, tetrapropylene glycol methyl n-hexyl ether; methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate Ester, n-butyl acetate, isobutyl acetate, second butyl acetate, n-amyl acetate, second amyl acetate, 3-methoxybutyl acetate, methyl amyl acetate, 2-ethyl butyl acetate Ester, 2-ethylhexyl acetate, 2-(2-butoxyethoxy) acetate Ethyl ester, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, decyl acetate, methyl acetate, ethyl acetate, diethylene glycol methyl ether, diethylene glycol monoacetate Ether, dipropylene glycol methyl ether acetate, dipropylene glycol ethyl ether, diacetate glycol, methoxytriethylene acetate, isoamyl acetate, ethyl propionate, n-butyl propionate, isoamyl propionate , diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, ethylene glycol methyl ether propionate, ethylene glycol ether propionate, ethylene glycol Ester solvent such as methyl ether acetate, ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, propylene glycol diethyl ether acetate, propylene glycol propyl ether acetate, γ-butyrolactone, γ-valerolactone; , N-methylpyrrolidone, N-ethylpyrrolidone, N-propylpyrrolidone, N-butylpyrrolidone, N-hexylpyrrolidone, N-cyclohexylpyrrolidone, N,N- Aprotic polar solvents such as dimethylformamide, N,N-dimethylacetamide, dimethylhydrazine; dichloromethane, chloroform, dichloroethane, benzene, toluene, xylene, hexane , hydrophobic liquid such as octane, ethylbenzene, 2-ethylhexanoic acid, methyl isobutyl ketone, methyl ethyl ketone; methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutyl Alcohol, second butanol, tert-butanol, n-pentanol, isoamyl alcohol, 2-methylbutanol, second pentanol, third pentanol, 3-methoxybutanol, n-hexanol, 2- Methyl pentanol, second hexanol, 2-ethylbutanol, second heptanol, n-octanol, 2-ethylhexanol, second octanol, n-nonanol, n-nonanol, second-ten Monoalkanol, trimethylnonyl alcohol, second-tetradecanol, second heptadecyl alcohol, cyclohexanol, methylcyclohexanol, isobornyl cyclohexanol, benzyl alcohol, ethylene glycol , 1,2-propanediol, 1,3-butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol and other alcohol solvents; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol Monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, Glycol monoether solvent such as ethylene glycol mono-n-hexyl ether, ethoxy triethylene glycol, tetraethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether a terpene solvent such as terpinene, terpineol, myrcene, allophymene, limonene, dipentene, decene, carbon, ocimene, and phellandrene; Water, etc. 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 a solvent selected from the group consisting of a hydrophobic organic solvent, an aprotic organic solvent, a terpene solvent, an ester solvent, an ether solvent, and an alcohol. At least one of the groups consisting of a solvent, more preferably containing a solvent selected from the group consisting of a terpene solvent, an ester solvent, and an alcohol solvent At least one of the resulting groups, and further preferably contains at least one selected from the group consisting of terpene solvents.

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

(resin)

The composition for forming a passivation layer preferably contains at least one resin. Further, the shape stability of the composition layer formed by imparting the composition for forming a passivation layer onto the semiconductor substrate by the resin is further improved, and the region in which the composition layer is formed can be selectively formed in a desired shape. Passivation layer.

The kind of the resin is not particularly limited. In particular, when the composition for forming a passivation layer is applied to a semiconductor substrate, the viscosity can be adjusted to a resin in a range in which good pattern formation can be performed. Specific examples of the resin include polyvinyl alcohol, polypropylene decylamine, polypropylene decylamine derivative, polyvinyl decylamine, polyvinyl decylamine derivative, polyvinylpyrrolidone, polyethylene oxide, and polycyclic ring. Oxyethane derivative, polysulfonic acid, acrylamide alkylsulfonic acid, cellulose, cellulose derivative (carboxymethyl cellulose, hydroxyethyl cellulose, cellulose ether, etc.), gelatin , gelatin derivatives, starch, starch derivatives, sodium alginate, sodium alginate derivatives, xanthan, xanthan gum derivatives, guar gum, guar gum derivatives, hard grapes Scleroglucan, scleroglucan derivative, tragacanth gum, yellow Silicone derivative, dextrin, dextrin derivative, (meth)acrylic resin, (meth)acrylate resin (alkyl (meth)acrylate resin, dimethylamine (meth)acrylate A vinyl ester resin or the like), a butadiene resin, a styrene resin, a decyl alkane resin, or the like. These resins may be used alone or in combination of two or more.

In the present specification, "(meth)acrylic acid" means at least one of "acrylic acid" and "methacrylic acid", and "(meth)acrylate" means "acrylic acid ester" and "methyl group". At least one of acrylates.

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 such as ethyl cellulose.

The molecular weight of the resins is not particularly limited, and is preferably appropriately adjusted in consideration of the desired viscosity as a composition for forming a passivation layer. The weight average molecular weight of the resin is preferably from 100 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 by a molecular weight distribution measured by Gel Permeation Chromatography (GPC). The calibration curve was obtained by a three-time approximation using five sample sets of standard polystyrene (PStQuick MP-H, PStQuick B [Tosoh Corporation, trade name]). The measurement conditions of GPC are shown below.

Device: (Pump: L-2130 [Hitachi High-Technologies Co., Ltd.])

(Detector: L-2490 Refractive Index (RI) [Hitachi High-Technologies Co., Ltd.])

(column oven: L-2350 [Hitachi High-Technologies Co., Ltd.])

Pipe column: Gelpack GL-R440+Gelpack GL-R450+Gelpack GL-R400M (3 in total) (Hitachi Chemical Co., Ltd., trade name)

Column size: 10.7mm (inside diameter) × 300mm

Dissolution: tetrahydrofuran

Sample concentration: 10mg/2mL

Injection volume: 200μL

Flow rate: 2.05mL/min

Measuring temperature: 25 ° C

When the composition for forming a passivation layer contains a resin, the content of the resin in the composition for forming a passivation layer may be appropriately selected as needed. For example, in the composition for forming a passivation layer, the content of the resin is preferably from 0.1% by mass to 30% by mass. The content of the resin is preferably from 1% by mass to 25% by mass, more preferably from 1.5% by mass to 20% by mass, even more preferably 1.5% by mass, from the viewpoint of exhibiting thixotropy such as pattern formation more easily. ~10% by mass.

When the composition for forming a passivation layer contains a resin, the content ratio of the specific metal compound to the resin may be appropriately selected as needed. In terms of pattern formation property and storage stability, the resin content ratio (resin/specific metal compound) is preferably 0.001 to 1000, based on the total amount of the specific metal compound. More preferably, it is 0.01 to 100, and further preferably 0.1 to 1.

The composition for forming a passivation layer may also 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.

The acidic compound may be listed as a Brilliant acid and a Lewis acid. Specific examples thereof include inorganic acids such as hydrochloric acid and nitric acid; and organic acids such as acetic acid. In addition, examples of the basic compound include a Bronsted base and a Lewis base. Specific examples of the basic compound include inorganic bases such as alkali metal hydroxides and alkaline earth metal hydroxides, and organic bases such as trialkylamine and pyridine. .

The composition for forming a passivation layer may optionally contain various additives such as a thickener, a wetting agent, a surfactant, an inorganic particle, a ruthenium atom-containing resin, and a thixotropic agent as other components.

The inorganic particles may be exemplified by cerium oxide (cerium oxide), clay, cerium carbide, cerium nitride, montmorillonite, bentonite, carbon black, etc. Among these inorganic particles, it is preferred to use oxidizing.填料 as a filler for the ingredients. Here, the so-called clay means a layered clay mineral, and specific examples thereof include kaolinite, imagolite, montmorillonite, smectite, sericite, and illite. ), talc, stevensite, zeolite, and the like. When the composition for forming a passivation layer contains inorganic particles, the imparting property of the composition for forming a passivation layer tends to be improved.

Examples of the surfactant include a nonionic surfactant, a cationic surfactant, an anionic surfactant, and the like. Among them, a nonionic surfactant or a cationic surfactant is preferred in that the amount of impurities such as heavy metals introduced into the semiconductor element is small. Further, the nonionic surfactant may be exemplified by a ruthenium surfactant, a fluorosurfactant, and a hydrocarbon surfactant. When the composition for forming a passivation layer contains a surfactant, the thickness of the composition layer formed by the composition for forming a passivation layer and the uniformity of composition tend to be improved.

The ruthenium-containing resin can be exemplified by an end-chain modified fluorenone, an alternating copolymer of polyamine and anthrone, a side chain alkyl fluorenone, a side chain polyether fluorenone, a terminal alkyl group. The oxime ketone, the fluorenone modified polytriglucose, the fluorenone modified acrylic acid, and the like. The thickness of the composition layer formed of the composition for forming a passivation layer and the uniformity of the composition tend to be improved.

The thixotropic agent can be exemplified by a polyether compound, a fatty acid guanamine, a fumed silica, a hydrogenated castor oil, a urea amide phthalamide, a polyvinylpyrrolidone, an oily gelling agent. Wait. When the composition for forming a passivation layer contains a thixotropic agent, there is a fine line formation property (improving the line width of the linear pattern when the composition for forming the passivation layer is applied and when the composition layer is dried) Propensity. The polyether compound may, for example, be polyethylene glycol, polypropylene glycol, poly(ethylidene-propyl) glycol copolymer or the like.

The viscosity of the composition for forming a passivation layer 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~10000Pa. s. Among them, the viscosity of the composition for forming a passivation layer is preferably 0.1 Pa from the viewpoint of pattern formation. s~1000Pa. s. Further, the viscosity was measured at a shear rate of 1.0 s ^-1 at 25 ° C using a rotary shear viscometer.

Further, the shear viscosity of the composition for forming a passivation layer is not particularly limited. Wherein, the viewpoint of the pattern formability, it is preferably a shear rate of 1.0s ^-1 shear viscosity η ₁ when divided by the shear rate 10s ^-1 shear viscosity η ₂ at the calculated thixotropic ratio (η ₁ /η ₂ ) is from 1.05 to 100, more preferably from 1.1 to 50. Further, the shear viscosity was measured at a temperature of 25 ° C using a rotary shear viscometer equipped with a cone plate (having a diameter of 50 mm and a taper angle of 1 °).

The method for producing the composition for forming a passivation layer is not particularly limited. For example, it can be produced by mixing a specific metal compound with a liquid medium or the like which is optionally contained by a method generally used. Alternatively, it may be produced by mixing a liquid medium in which a resin is dissolved with a specific metal compound.

Further, the specific metal compound may also mix a specific metal alkoxide compound of m=1 to 5 in the formula (I) with a compound which can form a chelate with a specific metal element contained in the specific metal alkoxide compound. And prepared. At this time, a liquid medium may be used as appropriate, or heat treatment may be performed. The composition for forming a passivation layer can also be produced using the specific metal compound thus prepared.

In addition, the type of the component contained in the composition for forming a passivation layer and the content of each component can be confirmed by the following analysis: thermal analysis such as thermogravimetric-differential thermal analysis (TG/DTA); Nuclear Magnetic Resonance (NMR), infrared spectroscopy (Infrared spectroscopy, IR) and other spectral analysis; High Performance Liquid Chromatography (HPLC), gel permeation chromatography (GPC) and other chromatographic analysis.

<Method of Manufacturing Solar Cell Element>

The method for producing a solar cell element according to the present invention includes the steps of: forming a light-receiving surface electrode on a light-receiving surface of the semiconductor substrate; and forming a back surface electrode on a back surface of the semiconductor substrate opposite to the light-receiving surface; a step of forming a composition layer by providing a composition for forming a passivation layer on at least one of the light-receiving surface, the back surface, and the side surface, wherein the composition for forming a passivation layer contains a material selected from the group consisting of Nb ₂ O ₅ , Ta ₂ O ₅ , and V ₂ At least one compound selected from the group consisting of O ₅ , Y ₂ O ₃ , HfO ₂ and a compound represented by the above formula (I); and a step of heat-treating the composition layer to form a passivation layer. The method of manufacturing the solar cell element of the present invention may further include other steps as needed. As for the composition for forming a passivation layer, those described in the solar cell element can be applied.

According to the above method, a passivation layer having an excellent passivation effect can be formed on a semiconductor substrate. Further, the passivation layer can be formed with high productivity by a simple method without a vapor deposition device or the like. Therefore, according to the above method, a solar cell element excellent in conversion efficiency can be manufactured by a simple method.

A method of forming a light-receiving surface electrode and a back surface electrode on a semiconductor substrate can be carried out by a usual method. For example, the electrode can be formed by applying an electrode for forming an electrode such as a silver paste or an aluminum paste to a desired region of the semiconductor substrate, and performing heat treatment (calcination) as necessary.

The step of forming the light-receiving surface electrode and the step of forming the back surface electrode may be the step of forming the composition layer by providing the composition for forming the passivation layer on at least one of the light-receiving surface, the back surface, and the side surface of the semiconductor substrate. after that. Further, the heat treatment (calcination) for forming the electrode and the heat treatment (calcination) for forming the passivation layer from the composition layer may be carried out together or separately as separate steps.

Further, it is preferable to further include a step of applying an alkaline aqueous solution to the semiconductor substrate before the step of forming the 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 the passivation layer 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.

A cleaning method using an alkaline aqueous solution can be exemplified by RCA (Radio Corporation of America) cleaning or the like which is generally known. For example, by immersing the semiconductor substrate in a mixed solution of aqueous ammonia-hydrogen peroxide water and treating it at 60 to 80 ° C, the organic material and the particles can be removed to clean the semiconductor substrate. The cleaning time is preferably from 10 seconds to 10 minutes, more preferably from 30 seconds to 5 minutes.

The method of forming the composition layer using the composition for forming a passivation layer on at least one of the light-receiving surface, the back surface, and the side surface of the semiconductor substrate is not particularly limited. For example, a method of providing a composition for forming a passivation layer on a semiconductor substrate by using a known method or the like can be mentioned. Specific examples thereof include a printing method such as a dipping method and a screen printing method, a spin coating method, a brush coating method, a spray method, a doctor blade method, a roll coating method, and an inkjet method. Among these methods, in terms of pattern formation, a screen printing is preferred. The brush method and the ink jet method are more preferably a screen printing method.

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

The composition layer formed by 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) conditions of the composition layer are not particularly limited. When the composition for forming a passivation layer contains a specific metal compound or another metal compound (organoaluminum compound or the like) which is an optional component, it can be converted into a specific metal oxide and other inorganic oxide which is a heat-treated product (calcined product). The material (aluminum oxide (Al ₂ O ₃ ) or the like), the heat treatment (calcination) condition of the composition layer is not particularly limited.

Among them, heat treatment (calcination) conditions for forming an amorphous specific metal oxide having no crystal structure are preferable. By forming the passivation layer from an amorphous specific metal oxide, the passivation layer can be more effectively negatively charged, and a more excellent passivation effect can be obtained. Specifically, the heat treatment (calcination) temperature is preferably 400 ° C or higher, more preferably 400 ° C to 900 ° C, and still more preferably 600 ° C to 800 ° C. The heat treatment (calcination) temperature herein means the highest temperature in the furnace used in the heat treatment (calcination). 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 5 seconds to 10 hours, preferably 10 seconds to 5 hours. The term "heat treatment (calcination)" as used herein refers to the retention time at the highest temperature.

Furthermore, heat treatment (calcination) can use a diffusion furnace (such as Akeron) (ACCURON) CQ-1200, Hitachi International Electric Co., Ltd.; 206A-M100, Koyo-Thermo System Co., Ltd., etc.). The environment in which the heat treatment (calcination) is carried out is not particularly limited and can be carried out in the atmosphere.

Further, before the step of heat-treating (calcining) the composition layer to form a passivation layer, a step of drying the composition layer may be further included. By having a step of drying the composition layer, a passivation layer having a more uniform passivation effect can be formed.

The step of drying the composition layer is not particularly limited as long as at least a part of the liquid medium which may be contained in the composition for forming a passivation layer can be removed. The drying treatment may be performed, for example, at 30 ° C to 250 ° C for 10 seconds to 60 minutes, preferably at 40 ° C to 220 ° C for 30 seconds to 10 minutes. Further, the drying treatment can be carried out under normal pressure or under reduced pressure.

Next, an embodiment of the present invention will be described with reference to the drawings.

Fig. 1 is a cross-sectional view showing a step diagram schematically showing an example of a method of manufacturing a solar cell element having a passivation layer according to the present embodiment. However, this step diagram does not in any way limit the method of use of the present invention.

As shown in FIG. 1(a), on the p-type semiconductor substrate 1, an n ⁺ -type diffusion layer 2 is formed in the vicinity of the surface, and an anti-reflection film 3 is formed on the surface. As the antireflection film 3, a tantalum nitride film, a titanium oxide film, or the like is known. A surface protective film (not shown) such as ruthenium oxide may be present between the anti-reflection film 3 and the p-type semiconductor substrate 1. Further, the passivation layer of the present invention can also be used as a surface protective film. In this case, although not shown, an antireflection film may be further laminated on the passivation layer to form a two-layer structure. When the passivation layer of the present invention is formed on the light-receiving surface, a solar cell (not shown) having a normal structure in which an aluminum electrode is formed on the entire back surface can be realized even if it is not a point contact structure as described later. Conversion efficiency.

Then, as shown in FIG. 1(b), a material for forming the back surface electrode 5 such as an aluminum electrode paste is applied to a partial region of the back surface, and then heat treatment (calcination) is performed to form the back surface electrode 5, and aluminum atoms are transferred to the p-type semiconductor. The substrate 1 is diffused to form a p ⁺ -type diffusion layer 4 .

Then, as shown in FIG. 1(c), the electrode forming paste is applied to the light-receiving surface side, and then heat-treated (calcined) to form the light-receiving surface electrode 7. By using a glass-containing paste containing burnt-through glass particles, the anti-reflection film 3 can be penetrated as shown in FIG. 1(c), and the light-receiving surface electrode 7 can be formed on the n ⁺ -type diffusion layer 2 to obtain Ohmic contact.

Then, as shown in FIG. 1(d), a composition for forming a passivation layer is provided on the p-type layer on the back surface other than the region in which the back surface electrode 5 is formed, and a composition layer is formed by screen printing or the like. The composition layer formed on the p-type layer is subjected to heat treatment (calcination) to form a passivation layer 6. By forming the passivation layer 6 on the p-type layer on the back surface, it is possible to manufacture a solar cell element having excellent power generation efficiency.

In the solar cell element manufactured by the manufacturing method including the manufacturing steps shown in FIG. 1, the back surface electrode containing aluminum or the like can be set to a point contact structure, and warpage of the substrate or the like can be reduced.

Further, a method of forming a passivation layer only on the back surface portion is shown in (d) of FIG. 1, and a composition for forming a passivation layer may be provided on the side surface in addition to the back surface of the p-type semiconductor substrate 1, and heat-treated. (Calcination), whereby a passivation layer 6 (not shown) is further formed on the side surface (edge) of the semiconductor substrate 1. Thereby, a solar cell element having more excellent power generation efficiency can be manufactured.

Further, the passivation layer may be formed on the side surface, and the passivation layer-forming composition of the present invention may be applied only to the side surface, and heat-treated (calcined) to form the passivation layer 6. When the composition for forming a passivation layer of the present invention is used for a portion having a large number of crystal defects such as a side surface, the effect is particularly large.

Although an embodiment in which a passivation layer is formed after forming an electrode has been described in FIG. 1, an electrode such as aluminum may be formed on the entire surface by vapor deposition or the like after forming a passivation layer, or may be formed on the entire surface. An electrode which does not require heat treatment (calcination) at a high temperature is formed.

Fig. 2 is a cross-sectional view showing a step chart schematically showing another example of a method of manufacturing a solar cell element having a passivation layer according to the present embodiment. Specifically, FIG. 2 illustrates a step diagram including a step of forming a p-type diffusion layer forming composition using an aluminum electrode paste or a p ⁺ -type diffusion layer by thermal diffusion treatment in the form of a cross-sectional view. ^{After the +} -type diffusion layer, the heat-treated product of the aluminum electrode paste or the heat-treated product of the composition for forming the p ⁺ -type diffusion layer is removed. Here, the p-type diffusion layer forming composition may be composed of, for example, a substance containing an acceptor element and a glass component.

As shown in FIG. 2(a), on the p-type semiconductor substrate 1, an n ⁺ -type diffusion layer 2 is formed in the vicinity of the surface, and an anti-reflection film 3 is formed on the surface. As the antireflection film 3, a tantalum nitride film, a titanium oxide film, or the like is known.

Then, in FIG. 2 (b) as shown, to impart a portion of the back surface region of the p ⁺ -type diffusion layer formed by heat treatment after the composition is formed a p ⁺ -type diffusion layer 4. A heat-treated product 8 of a composition for forming a p ⁺ -type diffusion layer is formed on the p ⁺ -type diffusion layer 4 .

Here, an aluminum electrode paste may be used instead of the p-type diffusion layer forming composition. In the case of using an aluminum electrode paste, an aluminum electrode is formed on the p ⁺ -type diffusion layer 4.

Then, as shown in FIG. 2(c), the heat-treated product 8 or the aluminum electrode of the p-type diffusion layer-forming composition formed on the p ⁺ -type diffusion layer 4 is removed by etching or the like.

Then, as shown in FIG. 2(d), a paste for electrode formation is selectively applied to a part of the light-receiving surface (surface) and the back surface, and heat treatment is performed to form a light-receiving surface electrode 7 on the light-receiving surface (surface). The back electrode 5 is formed on the back surface. By using the glass particles having the burn-through property as the paste for electrode formation provided on the light-receiving surface side, the anti-reflection film 3 can be penetrated as shown in FIG. 2(c) to form on the n ⁺ -type diffusion layer 2 . The ohmic contact is obtained by the light-receiving electrode 7.

Since the p ⁺ -type diffusion layer 4 is formed in the region where the back surface electrode is to be formed, the electrode forming paste for forming the back surface electrode 5 is not limited to the aluminum electrode paste, and an electrode having a lower electric resistance can be formed by using a silver electrode paste or the like. The electrode is used with a paste. Thereby, power generation efficiency can be further improved.

Then, as shown in FIG. 2(e), the composition for forming a passivation layer of the present invention is applied to the p-type layer on the back surface other than the region in which the back surface electrode 5 is formed, and a composition layer is formed. The application can be carried out by a method such as screen printing. The composition layer formed on the p ⁺ -type diffusion layer 4 is subjected to heat treatment (calcination) to form a passivation layer 6. By forming the passivation layer 6 on the p-type layer, a solar cell element excellent in power generation efficiency can be manufactured.

In addition, in FIG. 2(e), a method of forming a passivation layer only on the back surface portion is shown, but a composition for forming a passivation layer may be provided on the side surface in addition to the back surface side of the p-type semiconductor substrate 1, and heat treatment may be performed. (Calcination) whereby a passivation layer (not shown) is further formed on the side surface (edge) of the p-type semiconductor substrate 1. Thereby, a solar cell element having more excellent power generation efficiency can be manufactured.

Further, a passivation layer may be formed on the side surface, and the passivation layer-forming composition of the present invention may be applied only to the side surface, and heat-treated (calcined) to form a passivation layer. When the composition for forming a passivation layer of the present invention is used for a portion having a large number of crystal defects such as a side surface, the effect is particularly large.

Although an embodiment in which a passivation layer is formed after forming an electrode has been described in FIG. 2, an electrode such as aluminum may be formed on the entire surface by vapor deposition or the like after forming a passivation layer, or may be formed on the entire surface. An electrode which does not require heat treatment (calcination) at a high temperature is formed.

The above-described embodiment, the use of the form on the light surface of an n ⁺ case of a p-type semiconductor substrate type diffusion layer has been described, but using in the case of the n-type semiconductor substrate with a p ⁺ -type diffusion layer formed on the light receiving surface At the same time, the solar cell element can be manufactured in the same manner. Further, in this case, an n ⁺ -type diffusion layer is formed on the back side.

<Solar battery module>

The solar cell module of the present invention has the solar cell element as described above and a wiring material disposed on the electrode of the solar cell element. The solar cell module includes at least one of the solar cell elements described above, and is configured by disposing a wiring material such as a tape-automated bonding (TAB) wire on an electrode of the solar cell element. Further, the solar cell may be configured to connect a plurality of solar cell elements via a wiring material as needed, and to seal with a sealing material. The wiring material and the sealing material are not particularly limited and may be appropriately selected from those generally used in the technical field. The size of the above solar battery module is not limited. Preferably 0.5m ² ~ 3m ^2.

[Examples]

Hereinafter, the invention will be specifically described by way of examples, but the invention is not limited to the examples.

<Example 1>

(Preparation of a composition for forming a passivation layer)

Al ₂ O ₃ thin film coating material ("SYM-A104" of High Purity Chemical Research Co., Ltd., Al ₂ O ₃ : 2% by mass, xylene: 87% by mass, 2-propanol: 5% by mass, Stabilizer: 6 mass%) 1.0 g and Nb ₂ O ₅ film coating material (Nb-05, High Purity Chemical Research Co., Ltd., Nb ₂ O ₅ : 5 mass%, n-butyl acetate: 56 mass %, stabilizer: 16.5 mass%, viscosity modifier: 22.5 mass%) 1.0 g of the mixture, and the composition 1 for passivation layer formation was prepared.

(formation of passivation layer)

A single crystal type p-type ruthenium substrate (Mitsubishi Sumitomo (SUMCO) Co., Ltd., 50 mm square, thickness: 625 μm) having a mirror-shaped surface was used as the semiconductor substrate. Use RCA cleaning solution (Kanto Chemical Co., Ltd., cutting edge cleaning The agent (Frontier Cleaner)-A01) was immersed for 5 minutes at 70 ° C and washed to carry out pretreatment.

Then, the passivation layer-forming composition 1 obtained above was applied to the composition by a spin coater (Mikasa Co., Ltd., "MS-100") at 4000 rpm (min ^-1 ) for 30 seconds. The entire surface of the single side of the pretreated ruthenium substrate. Thereafter, drying treatment was performed at 150 ° C for 3 minutes. Then, after heat treatment (calcination) in air at 700 ° C for 10 minutes, it was left to cool at room temperature (25 ° C) to prepare a substrate for evaluation. The heat treatment (calcination) was carried out using a horizontal diffusion furnace (206A-M100, Koko Thermal Systems Co., Ltd.) under the conditions of a maximum temperature of 700 ° C and a holding time of 10 minutes in an atmospheric environment.

(Measurement of effective life)

The life measuring device (Semilab Co., Ltd., WT-2000PVN) was passivated by the reflection microwave photoconduction attenuating method at room temperature (25 ° C) to form the substrate for evaluation obtained above. The effective life (μs) of the layer area was measured. The effective life is 480μs.

(measurement of average thickness)

The thickness of the passivation layer at 5 points was measured using an interference type film thickness meter (Filmetrics Co., Ltd., F20 film thickness measurement system), and the average value was calculated. The average thickness is 82 nm.

(Measurement of density)

The density was calculated from the mass and average thickness of the passivation layer. The density was 3.2 g/cm ³ .

(production of solar cell components)

A 156 mm square p-type ruthenium substrate (formed by Advantec Co., Ltd.) in which an n-type diffusion layer is formed on both surfaces by using phosphorus oxychloride and a SiNx film is formed on one side (light-receiving side). N-type diffusion layer sheet resistance: 60 Ω / □, two-side texture treatment, SiNx film thickness: 80 nm), on the back side, by inkjet (Microjet Co., Ltd., inkjet device "MJP-1500V In the inkjet head: IJH-80, nozzle size: 50 μm × 70 μm, in the region 10 other than the opening portion 9, the film thickness after drying of the composition 1 for the passivation layer is formed. The composition for forming a passivation layer 1 was applied in a manner of 5 μm. Thereafter, drying treatment was performed at 150 ° C for 3 minutes. Then, using a horizontal diffusion furnace (206A-M100, Koko Thermal Systems Co., Ltd.), heat treatment (calcination) under the conditions of a maximum temperature of 700 ° C and a holding time of 1 hour in the atmosphere, and then left to cool to room temperature ( 25 ° C).

Thereafter, an aluminum electrode (PVG solvent (PVG Solutions) Co., Ltd., PVG-AD-02) was screen-printed on the back side in an overall pattern of 125 mm × 125 mm, and dried at 150 ° C for 3 minutes. Then, a silver electrode (Dupont Co., Ltd., PV159A) was screen-printed on the light-receiving side using the printed mask of the pattern shown in FIG. Then, after drying at 150 ° C, a solar cell element was produced by heat treatment (calcination) at 700 ° C using a tunnel type calciner (Noritake Co., Ltd.).

One hour after the production of the solar cell element, the solar cell element Solar Simulator (Wacom Electric Co., Ltd., XS-155S-10) was used to evaluate the power generation characteristics. The evaluation of power generation performance is Simulated sunlight (WXS-155S-10, Wacom Electric Co., Ltd.) and voltage-current (IV) evaluation tester (IV CURVE TRACER) MP-180, Yinghong Seiki ( The measuring device of the EKO INSTRUMENT) company is combined. Jsc (short circuit current density), Voc (open circuit voltage), FF (shape factor), and η (conversion efficiency) which are power generation performances of solar cells are respectively based on Japanese Industrial Standards (JIS)-C-8913 ( It was obtained by measuring in fiscal year 2005 and JIS-C-8914 (2005). The results are shown in Table 2.

Further, the produced solar cell element was placed in a constant temperature and humidity chamber at 50 ° C and 80% RH, and the power generation characteristics after one month of storage were evaluated. The results are shown in Table 3. The rate of change of the conversion efficiency after storage of the solar cell element (the conversion efficiency η ² [%] after storage with respect to the conversion efficiency η ¹ before storage) was 99.7%.

<Example 2>

(Preparation of a composition for forming a passivation layer)

Ta ₂ O ₅ film coating material (High Purity Chemical Research Institute Co., Ltd., "Ta-10-P", Ta ₂ O ₅ : 10% by mass, n-octane: 9 mass%, n-butyl acetate: 60 Mass%, stabilizer: 21% by mass) was used as the composition 2 for forming a passivation layer.

The evaluation substrate was produced in the same manner as in Example 1 except that the composition for forming the passivation layer 2 prepared above was used, and evaluation was performed in the same manner as in Example 1. The effective life is 450 μs. The passivation layer had a thickness of 75 nm and a density of 3.6 g/cm ³ .

A solar cell element was produced in the same manner as in Example 1 except that the composition for forming the passivation layer 2 was used instead of the composition 1 for forming the passivation layer, and the power generation characteristics were evaluated.

<Example 3>

HfO ₂ film coating material (High Purity Chemical Research Co., Ltd., "Hf-05", HfO ₂ content: 5% by mass, isoamyl acetate: 73% by mass, n-octane: 10% by mass, isopropyl Alcohol: 5% by mass, stabilizer: 7% by mass) as the composition 3 for forming a passivation layer.

An evaluation substrate was produced in the same manner as in Example 1 except that the composition for forming the passivation layer 3 prepared above was used, and evaluation was performed in the same manner as in Example 1. The effective life is 380μs. Thickness of the passivation layer is 71nm, a density of 3.2g / cm ^3.

A solar cell element was produced in the same manner as in Example 1 except that the composition for forming the passivation layer 3 was used instead of the composition 1 for forming the passivation layer, and the power generation characteristics were evaluated.

<Example 4>

Y ₂ O ₃ film coating material (High Purity Chemical Research Institute Co., Ltd., "Y-03", Y ₂ O ₃ : 3 mass%, 2-ethylhexanoic acid: 12.5% by mass, n-butyl acetate: 22.5% by mass, ethyl acetate: 8% by mass, terpinic oil: 45% by mass, viscosity adjuster: 9% by mass) was used as the composition 4 for forming a passivation layer.

The evaluation substrate was produced in the same manner as in Example 1 except that the composition for forming the passivation layer 4 prepared above was used, and evaluation was performed in the same manner as in Example 1. The effective life is 390μs. The passivation layer had a thickness of 68 nm and a density of 2.8 g/cm ³ .

A solar cell element was produced in the same manner as in Example 1 except that the composition for forming the passivation layer 4 was used instead of the composition for forming the passivation layer, and the power generation characteristics were evaluated.

<Example 5>

Ethylacetamidineacetic acid aluminum diisopropylate ("ALCH" manufactured by Kawasaki Seiki Co., Ltd.), pentaethoxy hydrazine (Beixing Chemical Industry Co., Ltd.), acetaminophen (Wako Pure Chemical Industries Co., Ltd.) , xylene (Wako Pure Chemical Industries Co., Ltd.), 2-propanol (Wako Pure Chemical Industries Co., Ltd.), and terpineol (Japanese Terpene Chemical Co., Ltd.) are mixed in the mixing ratio shown in Table 1, It is used as the composition 5 for forming a passivation layer.

A passivation layer was formed on the pretreated ruthenium substrate in the same manner as in Example 1 except that the passivation layer-forming composition 5 prepared above was used, and evaluation was performed in the same manner. The effective life is 420 μs. The thickness of the passivation layer is 94nm, a density of 2.6g / cm ^3.

A solar cell element was produced in the same manner as in Example 1 except that the composition for forming the passivation layer 5 was used instead of the composition 1 for forming the passivation layer, and the power generation characteristics were evaluated.

<Comparative Example 1>

In the first embodiment, the imparting of the composition for forming the passivation layer 1 is not performed, and A substrate for evaluation and a solar cell element were produced in the same manner as in Example 1. The effective life of the substrate for evaluation was measured and evaluated. The effective life is 20μs.

<Comparative Example 2>

5.0 g of ethyl cellulose (ETHOCEL 200 cps) as a resin and 95.0 g of terpineol (Nippon Terpene Chemical Co., Ltd.) as a liquid medium were mixed, and stirred at 150 ° C for 1 hour. An ethyl cellulose solution was prepared.

2.00 g of Al ₂ O ₃ particles (high-purity chemical research institute, average particle diameter: 1 μm), 1.98 g of terpineol, and 3.98 g of ethyl cellulose solution were mixed to prepare a colorless transparent composition C2.

The evaluation substrate was produced in the same manner as in Example 1 except that the composition C2 prepared above was used, and evaluated in the same manner as in Example 1. The effective life is 21 μs. The passivation layer had a thickness of 2.1 μm and a density of 1.4 g/cm ³ . Here, the thickness cannot be measured by an interferometric film thickness meter, and therefore it is measured by a stylus type step meter (AmBios, XP-2). Specifically, a part of the substrate was shaved with a spatula, and the step difference between the applied portion and the cut portion was measured under the conditions of a speed of 0.1 mm/s and a needle load of 0.5 mg. The measurement was performed three times, and the average value was calculated as the thickness.

A solar cell element was produced in the same manner as in Example 1 except that the composition C2 was used instead of the composition 1 for forming the passivation layer, and the power generation characteristics were evaluated.

<Comparative Example 3>

2.01 g of tetraethoxy decane and 1.99 g of terpineol were prepared in the same manner as in Comparative Example 2. 4.04 g of a prepared ethyl cellulose solution was mixed to prepare a colorless transparent composition C3.

An evaluation substrate was produced in the same manner as in Example 1 except that the composition C3 prepared above was used, and evaluation was performed in the same manner as in Example 1. The effective life is 23 μs. The passivation layer had a thickness of 85 nm and a density of 2.1 g/cm ³ .

A solar cell element was produced in the same manner as in Example 1 except that the composition C1 was used instead of the composition 1 for forming the passivation layer, and the power generation characteristics were evaluated.

As described above, the solar cell element of the present invention contains a passivation layer having an excellent passivation effect, so that high conversion efficiency is exhibited, and deterioration of temporal properties of solar cell characteristics is suppressed. Further, it is understood that the passivation layer of the solar cell element of the present invention can be formed into a desired shape by a simple procedure.

<Reference Embodiment 1>

The following is a passivation film, a coating material, a solar cell element, and a tantalum substrate with a passivation film according to the first embodiment.

<1> A passivation film containing aluminum oxide and cerium oxide for use in a solar cell element having a ruthenium substrate.

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

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

The passivation film of any one of <1> to <3> further contains an organic component.

The passivation film of any one of <1> to <4> which is A heat-treated product of a coating type material containing an alumina precursor and a cerium oxide precursor.

<6> A coating type material comprising an alumina precursor and a cerium oxide precursor for forming a passivation film of a solar cell element having a ruthenium substrate.

<7> A solar cell element comprising: a p-type germanium substrate comprising a single crystal germanium or a polycrystalline germanium, having a light receiving surface and a back surface opposite to the light receiving surface; and an n-type impurity diffusion layer formed on the light receiving surface side of the germanium substrate a first electrode formed on a surface of the n-type impurity diffusion layer on the light-receiving surface side of the ruthenium substrate, and a passivation film formed on a surface on the back surface side of the ruthenium substrate, having a plurality of openings and containing alumina And the second electrode is electrically connected to a surface on the back side of the tantalum substrate via the plurality of openings.

<8> A solar cell element comprising: a p-type germanium substrate comprising a single crystal germanium or a polycrystalline germanium, having a light receiving surface and a back surface opposite to the light receiving surface; and an n-type impurity diffusion layer formed on the light receiving surface side of the germanium substrate a first electrode formed on a surface of the n-type impurity diffusion layer on a light-receiving surface side of the germanium substrate; and a p-type impurity diffusion layer formed on a part or all of a back surface side of the germanium substrate to be larger than the germanium substrate a higher concentration is added with impurities; a passivation film is formed on the surface on the back side of the above-mentioned ruthenium substrate, and has a plurality of openings The mouth portion contains aluminum oxide and cerium oxide; and the second electrode is electrically connected to the surface of the p-type impurity diffusion layer on the back side of the ruthenium substrate via the plurality of openings.

<9> A solar cell component having: The n-type germanium substrate includes a single crystal germanium or a polycrystalline germanium, and has a light receiving surface and a back surface opposite to the light receiving surface; a p-type impurity diffusion layer is formed on the light receiving surface side of the germanium substrate; and a second electrode is formed on the germanium substrate a passivation film formed on the surface on the light-receiving surface side of the ruthenium substrate, having a plurality of openings and containing aluminum oxide and ruthenium oxide; and a first electrode formed on the light-receiving surface side of the ruthenium substrate The surface of the p-type impurity diffusion layer is electrically connected to the surface on the light-receiving surface side of the ruthenium substrate via the plurality of openings.

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

The solar cell element according to any one of the above aspects, wherein the total content of the cerium oxide and the aluminum oxide in the passivation film is 90% by mass or more.

<12> A ruthenium substrate having a passivation film having: a ruthenium substrate; and <1> to <5> on the entire surface or a portion of the ruthenium substrate A passivation film as described in any one of the above.

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

The passivation film of this embodiment is a passivation film used for a tantalum solar cell element, and contains aluminum oxide and ruthenium oxide.

Further, in the present embodiment, the amount of fixed charge of the film can be controlled by changing the composition of the passivation film.

Further, from the viewpoint of stabilizing the negative fixed charge, it is more preferable that the mass ratio of cerium oxide to aluminum oxide is 30/70 to 80/20. Further, from the viewpoint of making the negative fixed charge more stable, it is preferable that the mass ratio of cerium oxide to aluminum oxide is 35/65 to 70/30. Further, from the viewpoint of improving the life of the carrier and the negative fixed charge, the mass ratio of cerium oxide to aluminum oxide is preferably 50/50 to 90/10.

The mass ratio of cerium oxide to aluminum oxide in the passivation film can be determined by Energy Dispersive X-ray spectroscope (EDX), Secondary Ion Mass Spectrometer (SIMS) and high frequency. Inductively coupled plasma-mass spectrometry (ICP-MS) was used for the determination. The specific measurement conditions are as follows. Dissolving the passivation film in an acid or alkaline aqueous solution, forming the solution into a mist and introducing it into the Ar plasma, and splitting the light emitted by the excited element back to the ground state to measure the wavelength and intensity. The degree of the element was determined according to the obtained wavelength, and the amount was quantified based on the obtained intensity.

The total content of cerium oxide and aluminum oxide in the passivation film is preferably 80% by mass or more, and more preferably 90% by mass or more from the viewpoint of maintaining good characteristics. When the components of cerium oxide and aluminum oxide in the passivation film are increased, the effect of negatively fixing charges becomes large.

The total content of cerium oxide and aluminum oxide in the passivation film can be determined by combining thermogravimetric analysis, fluorescent X-ray analysis, ICP-MS, and X-ray absorption spectroscopy. The specific measurement conditions are as follows. The ratio of the inorganic component was calculated by thermogravimetric analysis, and the ratio of cerium to aluminum was calculated by fluorescence X-ray or ICP-MS analysis, and the ratio of the oxide was examined by X-ray absorption spectroscopy.

Further, in the passivation film, from the viewpoint of improving the film quality or adjusting the elastic modulus, components other than cerium oxide and aluminum oxide can be contained in the form of an organic component. The presence of the organic component in the passivation film can be confirmed by elemental analysis and Fourier transform infrared spectroscopy (FT-IR) measurement of the film.

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

The passivation film can also be obtained in the form of a heat-treated product of a coating type material containing an alumina precursor and a cerium oxide precursor. The coating type material will be described in detail below.

The coating material of the present embodiment contains an alumina precursor and cerium oxide. A precursor for forming a passivation film for a solar cell element having a germanium substrate.

The alumina precursor can be used without particular limitation as long as it forms alumina. The alumina precursor preferably uses an organic alumina precursor in terms of uniform dispersion of alumina on the tantalum substrate and chemical stability. Examples of the organic alumina precursors include aluminum triisopropoxide (structural formula: Al(OCH(CH ₃ ) ₂ ) ₃ ), SYM-AL04 of High Purity Chemical Research Institute Co., Ltd., and the like.

The cerium oxide precursor can be used without particular limitation as long as it forms cerium oxide. From the viewpoint of uniformly dispersing cerium oxide on the cerium substrate and chemical stability, the cerium oxide precursor is preferably an organic cerium oxide precursor. Examples of the organic cerium oxide precursor include cerium (V) (structural formula: Nb(OC ₂ H ₅ ) ₅ , molecular weight: 318.21), and Nb-05 of the High Purity Chemical Research Institute.

A coating type material containing an organic cerium oxide precursor and an organic alumina precursor is formed into a film by a coating method or a printing method, and the organic component is removed by heat treatment (calcination) thereafter. Passivation film. Therefore, the result may also be a passivation film containing an organic component.

<Structure Description of Solar Cell Components>

The structure of the solar cell element of the present embodiment will be described with reference to Figs. 6 to 9 . FIG. 6 to FIG. 9 are cross-sectional views showing a first configuration example to a fourth configuration example of a solar battery element using a passivation film on the back surface of the embodiment.

As the tantalum substrate (crystalline germanium substrate, semiconductor substrate) 101 used in the present embodiment, any of single crystal germanium or polycrystalline germanium can be used. In addition, the germanium substrate 101 can be used as a guide The electric type is either a p-type crystalline germanium or a conductive type n-type crystalline germanium. From the viewpoint of further exerting the effects of the present embodiment, it is more preferable that the conductivity type is a p-type crystal ruthenium.

In the following FIGS. 6 to 9, an example in which a p-type single crystal germanium is used as the germanium substrate 101 will be described. In addition, the single crystal germanium or polycrystalline germanium used in the germanium substrate 101 may be any, preferably having a resistivity of 0.5 Ω. Cm~10Ω. Cm single crystal germanium or polycrystalline germanium.

As shown in FIG. 6 (the first configuration example), an n-type diffusion layer 102 doped with a group V element such as phosphorus is formed on the light-receiving surface side (upper side, first surface) of the p-type germanium substrate 101. Further, a pn junction is formed between the germanium substrate 101 and the diffusion layer 102. On the surface of the diffusion layer 102, a light-receiving surface anti-reflection film 103 such as a tantalum nitride (SiN) film or a first electrode 105 (such as an electrode on the light-receiving surface side, a first surface electrode, and an upper surface) using silver (Ag) or the like is formed. Surface electrode, light receiving surface electrode). The light-receiving surface anti-reflection film 103 can also function as a light-receiving surface passivation film. By using the SiN film, both the function of the light-receiving surface anti-reflection film and the light-receiving surface passivation film can be achieved.

Further, the solar cell element of the present embodiment may have the light-receiving surface anti-reflection film 103 or may not have the light-receiving surface anti-reflection film 103. Further, in order to reduce the reflectance of the surface on the light-receiving surface of the solar cell element, it is preferable to form a concavo-convex structure (texture structure), and the solar cell element of the present embodiment may have a textured structure or may have no texture structure.

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

In order to contact (electrically connect) the BSF layer 104 (the surface on the back side of the ruthenium substrate 101 when the BSF layer 104 is not present) on the back surface side of the ruthenium substrate 101, a second layer made of aluminum or the like is formed. Electrode 106 (electrode on the back side, second surface electrode, back surface electrode).

Then, in FIG. 6 (the first configuration example), a contact region electrically connected to the second electrode 106 is provided in addition to the BSF layer 104 (the surface on the back side of the ruthenium substrate 101 when the BSF layer 104 is not present). A passivation film (passivation layer) 107 containing aluminum oxide and cerium oxide is formed in a portion other than the opening OA). The passivation film 107 of the present embodiment may have a negative fixed charge. By this fixed electric charge, electrons, which are a minority carrier in the carrier generated in the crucible substrate 101 by light, are reflected back to the surface side. Therefore, the short-circuit current is increased, and the photoelectric conversion efficiency can be expected to be improved.

Next, a second configuration example shown in FIG. 7 will be described. In FIG. 6 (first configuration example), the second electrode 106 is formed on the entire surface of the contact region (opening portion OA) and the passivation film 107, and in FIG. 7 (second configuration example), only the contact is made. The second electrode 106 is formed in the region (opening OA). It is also possible to adopt a configuration in which the second electrode 106 is formed on only a part of the contact region (opening OA) and the passivation film 107. Even in the solar cell element having the configuration shown in Fig. 7, the same effects as those in Fig. 6 (first configuration example) can be obtained.

Next, a third configuration example shown in FIG. 8 will be described. In the third configuration example shown in FIG. 8, the BSF layer 104 is formed to include the connection with the second electrode 106. Only a part of the back surface side of the contact region (the opening portion OA portion) is formed on the entire surface on the back surface side as in the case of FIG. 6 (the first configuration example). Even in the solar cell element (FIG. 8) having such a configuration, the same effects as those of FIG. 6 (the first configuration example) can be obtained. Further, according to the solar cell element of the third configuration example of FIG. 8, the BSF layer 104 is doped with a group III element such as aluminum or boron, and a region having a higher concentration than the germanium substrate 101 is doped with impurities. Photoelectric conversion efficiency higher than that of Fig. 6 (first configuration example) can be obtained.

Next, a fourth configuration example shown in FIG. 9 will be described. In FIG. 8 (third configuration example), the second electrode 106 is formed on the entire surface of the contact region (opening OA) and the passivation film 107, and in FIG. 9 (fourth configuration example), only the contact is made. The second electrode 106 is formed in the region (opening OA). It is also possible to adopt a configuration in which the second electrode 106 is formed on only a part of the contact region (opening OA) and the passivation film 107. Even in the solar cell element having the configuration shown in Fig. 9, the same effects as those of Fig. 8 (the third configuration example) can be obtained.

In addition, when the second electrode 106 is applied by a printing method and is formed on the entire surface on the back side by firing at a high temperature, warping of the upward convexity is likely to occur during the temperature lowering process. Such warpage sometimes causes damage to the solar cell components, and the yield may be lowered. In addition, the problem of warpage during the development of the thin film of the tantalum substrate becomes large. The reason for this warpage is that the second electrode 106 including a metal (for example, aluminum) has a thermal expansion coefficient larger than that of the tantalum substrate, and thus the shrinkage during the cooling process is large, so that stress is generated.

According to the above, when the second electrode 106 is not formed on the entire surface on the back side as shown in FIG. 7 (the second configuration example) and FIG. 9 (the fourth configuration example), The electrode structure is likely to be vertically symmetrical, and it is less likely to cause stress due to the difference in thermal expansion coefficient, which is preferable. In this case, it is preferable to further provide a reflective layer.

<Method of Manufacturing Solar Cell Components>

Next, an example of a method of manufacturing the solar cell element (Figs. 6 to 9) of the present embodiment having the above configuration will be described. However, the present embodiment is not limited to the solar cell element produced by the method described below.

First, a texture structure is formed on the surface of the ruthenium substrate 101 shown in FIG. 6 and the like. The formation of the texture structure may be formed on both surfaces of the ruthenium substrate 101, or may be formed only on one side (the light-receiving surface side). In order to form a texture structure, the tantalum substrate 101 is first immersed in a solution of heated potassium hydroxide or sodium hydroxide to remove the damaged layer of the tantalum substrate 101. Thereafter, it is immersed in a solution containing potassium hydroxide and isopropyl alcohol as a main component, whereby a texture structure is formed on both surfaces or one side (light-receiving surface side) of the ruthenium substrate 101. Further, as described above, the solar cell element of the present embodiment may have a textured structure or a textured structure, and this step may be omitted.

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

Thereafter, a solution containing a coating type doping material such as boron or aluminum is applied to the back surface side of the tantalum substrate 101, and heat treatment is performed to form the BSF layer 104 on the back side. At the time of application, methods such as screen printing, inkjet, dispensing, and spin coating can be used. After the heat treatment, a layer such as borosilicate glass or aluminum formed on the back surface is removed by hydrofluoric acid, hydrochloric acid or the like to form the BSF layer 104. The method of forming the BSF layer 104 is not particularly limited. It is preferable that the BSF layer 104 is formed in such a manner that the concentration of boron, aluminum, or the like is in the range of 10 ¹⁸ cm ^-3 to 10 ²² cm ^-3 , and it is preferable to form the BSF layer 104 in a dot shape or a line shape. . Further, the solar cell element of the present embodiment may have the BSF layer 104 or may not have the BSF layer 104, and this step may be omitted.

Further, when the diffusion layer 102 on the light-receiving surface and the BSF layer 104 on the back surface are formed using a solution of a coating-type dopant, the solution of the dopant may be applied to the substrate 101, respectively. On both sides, a phosphorus diffusion layer (n ⁺ layer) as the diffusion layer 102 is formed together with the BSF layer 104, and thereafter phosphorus glass, borosilicate glass or the like formed on the surface is removed together.

Thereafter, a tantalum nitride film as the light-receiving surface anti-reflection film 103 is formed on the diffusion layer 102. The method of forming the light-receiving surface anti-reflection film 103 is not particularly limited. The light-receiving surface anti-reflection film 103 is preferably formed to have a thickness in the range of 50 nm to 100 nm and a refractive index of 1.9 to 2.2. The light-receiving surface anti-reflection film 103 is not limited to the tantalum nitride film, and may be a hafnium oxide film, an aluminum oxide film, a titanium oxide film or the like. The surface anti-reflection film 103 such as a tantalum nitride film can be formed by plasma CVD, thermal CVD, or the like, preferably by forming the surface anti-reflection film 103 in a temperature range of 350 ° C to 500 ° C. The surface anti-reflection film 103 is formed by plasma CVD.

Then, a passivation film 107 is formed on the back side of the germanium substrate 101. The passivation film 107 contains aluminum oxide and cerium oxide, and is formed, for example, by imparting heat treatment (calcination) to a material (passivation material) containing an organic material which can be obtained by heat treatment (calcination) to obtain alumina. An alumina precursor represented by a metal decomposition coating type material and a cerium oxide precursor represented by a commercially available organometallic decomposition coating type material which can be obtained by heat treatment (calcination) to obtain cerium oxide.

The formation of the passivation film 107 can be performed, for example, as follows. The coated material was spin-coated on a single side of a 8 吋 (20.32 cm) p-type ruthenium substrate (8 Ω cm to 12 Ω cm) having a thickness of 725 μm in which the natural oxide film was 725 μm, which was previously removed by using hydrofluoric acid having a concentration of 0.049% by mass. The prebaking was carried out on a hot plate at 120 ° C for 3 minutes. Thereafter, heat treatment was performed at 650 ° C for 1 hour under a nitrogen atmosphere. In this case, a passivation film containing aluminum oxide and cerium oxide can be obtained. The film thickness of the passivation film 107 formed by the method described above by an ellipsometer is usually about several tens of nanometers (nm).

The coating material is applied to a predetermined pattern including a contact region (opening OA) by a method such as screen printing, pattern printing, inkjet printing, or printing by a dispenser. Further, it is preferable that the coating material is prebaked in a range of from 80 ° C to 180 ° C after the application, and the solvent is evaporated, and then subjected to a nitrogen atmosphere or air at 600 ° C to 1000 ° C for 30 minutes. Heat treatment (annealing) for about 3 hours to form a passivation film 107 (film of an oxide).

Further, the opening (hole for contact) OA is preferably in the form of dots or lines It is formed on the BSF layer 104.

The passivation film 107 used in the above solar cell element preferably has a mass ratio of cerium oxide to aluminum oxide (yttria/alumina) of 30/70 to 90/10, more preferably 30/70 to 80/20, and further preferably It is 35/65~70/30. Thereby, the negative fixed charge can be stabilized. Further, from the viewpoint of improving the life of the carrier and the negative fixed charge, the mass ratio of cerium oxide to aluminum oxide is preferably 50/50 to 90/10.

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

Then, the first electrode 105 which is an electrode on the light-receiving surface side is formed. The first electrode 105 is formed by forming a paste containing silver (Ag) as a main component on the light-receiving surface anti-reflection film 103 by screen printing, and performing heat treatment (burn-through). The shape of the first electrode 105 may be any shape, and may be, for example, a well-known shape including a finger electrode and a bus bar electrode.

Then, the second electrode 106 which is an electrode on the back side is formed. The second electrode 106 is formed by applying a paste containing aluminum as a main component using a screen printing or a dispenser, and heat-treating the same. Further, the shape of the second electrode 106 is preferably the same shape as that of the BSF layer 104, the shape of the entire surface covering the back surface side, a comb shape, a lattice shape, or the like. In addition, printing of a paste for forming the first electrode 105 and the second electrode 106 as electrodes on the light-receiving surface side may be performed first, and then heat treatment (burn-through) may be performed to form the first electrode 105 and the second electrode together. Electrode 106.

In addition, when the second electrode 106 is formed, aluminum (Al) is used. The paste as a main component is diffused with aluminum as a dopant, and the BSF layer 104 is formed in a contact portion between the second electrode 106 and the ruthenium substrate 101 in a self-aligned manner. Further, as described above, a solution containing a coating type doping material such as boron or aluminum may be applied to the back surface side of the tantalum substrate 101, and heat-treated to form the BSF layer 104.

Further, the above shows a configuration example and a manufacturing example in which a p-type germanium is used for the germanium substrate 101, and an n-type germanium substrate can be used as the germanium substrate 101. In this case, the diffusion layer 102 is formed by a layer doped with a group III element such as boron, and the BSF layer 104 is formed by doping a group V element such as phosphorus. In this case, it is necessary to pay attention to the fact that the negative electrode formed on the interface and the portion in contact with the metal on the back side communicate with each other and the leakage current flows, and the conversion efficiency is hard to be improved.

Further, in the case of using an n-type germanium substrate, the passivation film 107 containing cerium oxide and aluminum oxide can be used for the light-receiving surface side as shown in FIG. FIG. 10 is a cross-sectional view showing a configuration example of a solar cell element using the light-receiving surface passivation film of the embodiment.

In this case, the diffusion layer 102 on the light-receiving surface side is doped with boron to form a p-type, and the holes in the generated carriers are collected on the light-receiving surface side, and electrons are collected on the back surface side. Therefore, it is preferable that the passivation film 107 having a negative fixed charge is located on the light receiving surface side.

An antireflection film made of SiN or the like may be further formed on the passivation film containing cerium oxide and aluminum oxide by CVD or the like.

Hereinafter, the reference embodiment and the reference comparative example of the present embodiment will be described in detail.

[Reference Example 1-1]

A commercially available organometallic decomposition coating material which can obtain alumina (Al ₂ O ₃ ) by heat treatment (calcination) [SYM-AL04 of High Purity Chemical Research Institute Co., Ltd., concentration: 2.3% by mass] 3.0 g, a commercially available organometallic decomposition coating material which can obtain cerium oxide (Nb ₂ O ₅ ) by heat treatment (calcination) [Nb-05 of High Purity Chemical Research Institute Co., Ltd., concentration: 5% by mass ] 3.0 g was mixed to prepare a passivation material (a-1) as a coating type material.

The passivation material (a-1) was spin-coated on a single surface of an 8-inch p-type tantalum substrate (8 Ωcm to 12 Ωcm) having a thickness of 725 μm of a natural oxide film removed by using hydrofluoric acid having a concentration of 0.049% by mass. Prebaking was carried out on a hot plate at 120 ° C for 3 minutes. Thereafter, heat treatment (calcination) was carried out at 650 ° C for 1 hour in a nitrogen atmosphere to obtain a passivation film containing alumina and cerium oxide [cerium oxide/alumina = 68/32 (mass ratio)]. The film thickness was measured by an ellipsometer and found to be 43 nm. The FT-IR of the passivation film was measured, and as a result, a very weak peak derived from an alkyl group was observed in the vicinity of 1200 cm ^-1 .

Then, on the passivation film, a plurality of aluminum electrodes having a diameter of 1 mm were formed by vapor deposition in the metal mask to form a capacitor of a metal-insulator-semiconductor (MIS) structure. The voltage dependence (CV characteristic) of the capacitance of the capacitor was measured by a commercially available prober and an LCR meter (HP company, 4275A). The results show that the flat band voltage (Vfb) is shifted from the ideal value of -0.81V to +0.32V. From the amount of movement, it was found that the passivation film obtained from the passivation material (a-1) showed a fixed charge having a fixed charge density (Nf) of -7.4 × 10 ¹¹ cm ^-2 and a negative value.

The passivation material (a-1) is imparted to the 8-inch p-type fluorenyl group in the same manner as described above. Both sides of the plate were prebaked, and heat-treated (calcined) at 650 ° C for 1 hour in a nitrogen atmosphere to prepare a sample covered with a passivation film on both sides of the ruthenium substrate. The measurement of the carrier lifetime of these samples was carried out by a life measuring device (Kobelco Research Institute Co., Ltd., RTA-540). The resulting carrier lifetime was 530 μs. For comparison, the same 8-inch p-type ruthenium substrate was passivated and measured by iodine passivation, and the carrier lifetime was 1100 μs.

From the above, it is known that the passivation film obtained by subjecting the passivation material (a-1) to heat treatment (calcination) exhibits a certain degree of passivation performance and exhibits a negative fixed charge.

[Reference Example 1-2]

In the same manner as in Reference Example 1-1, a commercially available organometallic decomposition coating material which can be obtained by heat treatment (calcination) of alumina (Al ₂ O ₃ ) [High Purity Chemical Research Institute Co., Ltd., SYM -AL04, a concentration of 2.3% by mass], and a commercially available organometallic decomposition coating material capable of obtaining cerium oxide (Nb ₂ O ₅ ) by heat treatment (calcination) [High Purity Chemical Research Institute Co., Ltd., Nb -05, a concentration of 5% by mass] was mixed and changed, and the passivation material (a-2) to passivation material (a-7) shown in Table 4 was prepared.

In the same manner as in Reference Example 1-1, the passivation material (a-2) to the passivation material (a-7) were respectively applied to one surface of the p-type germanium substrate, and heat treatment (calcination) was performed to prepare a passivation film. The voltage dependence of the capacitance of the obtained passivation film was measured, and the fixed charge density was calculated based on this.

Further, in the same manner as in Reference Example 1-1, a passivation material was applied to both surfaces of the p-type ruthenium substrate, and heat treatment (calcination) was carried out, and the obtained sample was used for measurement. Carrier life. The results obtained are summarized in Table 4.

Depending on the ratio (mass ratio) of cerium oxide/alumina after heat treatment (calcination), the results are different, but regarding the passivation material (a-2) to passivation material (a-7), the carrier life after heat treatment (calcination) It also shows a certain degree of value, so it is suggested to function as a passivation film. It is known that the passivation film obtained from the passivation material (a-2) to the passivation material (a-7) stably exhibits a negative fixed charge, and can also be preferably used as a passivation film of a p-type germanium substrate.

[Reference Example 1-3]

Commercially available ruthenium (V) (structural formula: Nb(OC ₂ H ₅ ) ₅ , molecular weight: 318.21) 3.18 g (0.010 mol), commercially available aluminum triisopropoxide (structural formula: Al (OCH) CH ₃ ) ₂ ) ₃ , molecular weight: 204.25) 1.02 g (0.005 mol) was dissolved in 80 g of cyclohexane to prepare a passivation material (c-1) having a concentration of 5% by mass.

The passivation material (c-1) was spin-coated on a single surface of an 8-inch p-type tantalum substrate (8 Ωcm to 12 Ωcm) having a thickness of 725 μm of a natural oxide film removed by using hydrofluoric acid having a concentration of 0.049% by mass. Prebaking was carried out on a hot plate at 120 ° C for 3 minutes. Thereafter, heat treatment (calcination) was performed at 600 ° C for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and cerium oxide. The film thickness was measured by an ellipsometer and found to be 50 nm. As a result of performing elemental analysis, it was found that Nb/Al/C = 81/14/5 (% by mass). The FT-IR of the passivation film was measured, and as a result, a very weak peak derived from an alkyl group was observed in the vicinity of 1200 cm ^-1 .

Then, on the passivation film, a plurality of aluminum electrodes having a diameter of 1 mm were formed by vapor deposition in the metal mask to form a capacitor of a metal-insulator-semiconductor (MIS) structure. The voltage dependence (CV characteristic) of the capacitance of the capacitor was measured by a commercially available prober and an LCR meter (HP company, 4275A). The results show that the flat band voltage (Vfb) is shifted from the ideal value of -0.81V to +4.7V. From the amount of movement, it was found that the passivation film obtained from the passivation material (c-1) exhibited a fixed charge having a fixed charge density (Nf) of -3.2 × 10 ¹² cm ^-2 and a negative value.

In the same manner as described above, the passivation material (c-1) was applied to both surfaces of a p-type ruthenium substrate of 8 Å, prebaked, and heat-treated (calcined) at 600 ° C for 1 hour in a nitrogen atmosphere to prepare a ruthenium substrate. A sample covered by a passivation film on both sides. The measurement of the carrier lifetime of these samples was carried out by a life measuring device (Kobelco Research Institute Co., Ltd., RTA-540). The resulting carrier lifetime was 330 μs. For comparison, the same 8-inch p-type ruthenium substrate was passivated and measured by iodine passivation, and the carrier lifetime was 1100 μs.

It is known from the above that the passivation material (c-1) is subjected to heat treatment (calcination) The resulting passivation film showed some degree of passivation performance, showing a negative fixed charge.

[Reference Examples 1-4]

Commercially available ruthenium (V) (structural formula: Nb(OC ₂ H ₅ ) ₅ , molecular weight: 318.21) 2.35 g (0.0075 mol), commercially available triisopropoxy aluminum (structural formula: Al (OCH) CH ₃ ) ₂ ) ₃ , molecular weight: 204.25) 1.02g (0.005mol), 10g of novolak resin was dissolved in 10g of diethylene glycol monobutyl ether acetate and 10g of cyclohexane to prepare passivation material (c-2) .

The passivation material (c-2) was spin-coated on a single surface of an 8-inch p-type ruthenium substrate (8 Ωcm to 12 Ωcm) having a thickness of 725 μm of a natural oxide film removed by using hydrofluoric acid having a concentration of 0.049% by mass. Prebaking was carried out on a hot plate at 120 ° C for 3 minutes. Thereafter, heat treatment (calcination) was performed at 600 ° C for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and cerium oxide. The film thickness was measured by an ellipsometer and found to be 14 nm. As a result of elemental analysis, Nb/Al/C = 75/17/8 (% by mass) was obtained. The FT-IR of the passivation film was measured, and as a result, a very weak peak derived from an alkyl group was observed in the vicinity of 1200 cm ^-1 .

Then, on the passivation film, a plurality of aluminum electrodes having a diameter of 1 mm were formed by vapor deposition through a metal mask to form a capacitor of a metal-insulator-semiconductor (MIS) structure. The voltage dependence (CV characteristic) of the capacitance of the capacitor was measured by a commercially available prober and an LCR meter (HP company, 4275A). The results show that the flat band voltage (Vfb) is shifted from the ideal value of -0.81V to +0.10V. From the amount of movement, it was found that the passivation film obtained from the passivation material (c-2) showed a fixed charge having a fixed charge density (Nf) of -0.8 × 10 ¹¹ cm ^-2 and a negative value.

In the same manner as described above, the passivation material (c-2) was applied to both surfaces of a p-type ruthenium substrate of 8 Å, prebaked, and heat-treated (calcined) at 600 ° C for 1 hour in a nitrogen atmosphere to prepare a ruthenium substrate. A sample covered by a passivation film on both sides. The measurement of the carrier lifetime of the sample was carried out by a life measuring device (Kobelco Research Institute Co., Ltd., RTA-540). The resulting carrier lifetime was 200 μs. For comparison, the same 8-inch p-type ruthenium substrate was passivated and measured by iodine passivation, and the carrier lifetime was 1100 μs.

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

[Reference Examples 1-5 and Reference Comparative Example 1-1]

In the same manner as in Reference Example 1-1, a commercially available organometallic decomposition coating material which can obtain alumina (Al ₂ O ₃ ) by heat treatment (calcination) [SYM of High Purity Chemical Research Institute Co., Ltd.] -AL04, a concentration of 2.3% by mass], and a commercially available organometallic decomposition coating material capable of obtaining cerium oxide (Nb ₂ O ₅ ) by heat treatment (calcination) [Nb of High Purity Chemical Research Institute Co., Ltd. -05, the concentration was changed to 5% by mass], and the ratio was changed to prepare a passivation material (b-1) to a passivation material (b-7) shown in Table 5.

In the same manner as in Reference Example 1-1, the passivation material (b-1) to the passivation material (b-7) were respectively applied to one surface of the p-type germanium substrate, and heat treatment (calcination) was performed to prepare a passivation film. The passivation film measures the voltage dependence of the electrostatic capacitance, and calculates the fixed charge density based on this.

Further, in the same manner as in Reference Example 1-1, a passivation material (coating type material) was applied to both surfaces of the p-type ruthenium substrate, and the carrier life was measured using the cured sample. The results obtained are summarized in Table 5.

It is known that the passivation film obtained from the passivation material (b-1) to the passivation material (b-6) has a large carrier life and functions as a passivation. Further, in the case where the cerium oxide/alumina is 10/90 and 20/80, the value of the fixed charge density is largely deviated, and the negative fixed charge density cannot be stably obtained, but it can be confirmed that alumina and cerium oxide can be used. Achieve a negative fixed charge density. It has been found that when a passivation material having yttria/alumina of 10/90 and 20/80 is used for measurement by the CV method, it may become a passivation film which exhibits a positive fixed charge, and thus does not stably exhibit a negative fixation. Charge. Further, a passivation film exhibiting a positive fixed charge can be used as a passivation film of an n-type germanium substrate.

On the other hand, the passivation material (b-7) in which the alumina reaches 100% by mass cannot obtain a negative fixed charge density.

[Reference Comparative Example 1-2]

A commercially available organometallic decomposition coating material which can be obtained as a passivation material (d-1) by heat treatment (calcination) to obtain titanium oxide (TiO ₂ ) [Ti-03- of High Purity Chemical Research Institute Co., Ltd. P, a concentration of 3% by mass], a commercially available organometallic decomposition coating material capable of obtaining barium titanate (BaTiO ₃ ) by heat treatment (calcination) as a passivation material (d-2) [High Purity Chemistry Research] BT-06 of the company, a concentration of 6% by mass], and commercially available organometallic decomposition coating of lanthanum oxide (HfO ₂ ) which can be obtained by heat treatment (calcination) as a passivation material (d-3) Type material [Hf-05 of High Purity Chemical Research Institute Co., Ltd., concentration of 5% by mass].

In the same manner as in Reference Example 1-1, the passivation material (d-1) to the passivation material (d-3) were respectively applied to one surface of the p-type germanium substrate, and then heat treatment (calcination) was performed to prepare a passivation film. The passivation film measures the voltage dependence of the electrostatic capacitance, and calculates the fixed charge density based on this.

Further, in the same manner as in Reference Example 1-1, a passivation material was applied to both surfaces of the p-type ruthenium substrate, and a sample obtained by heat treatment (calcination) was used to measure the carrier lifetime. The results obtained are summarized in Table 6.

Know the passivation obtained from passivation material (d-1) ~ passivation material (d-3) The carrier life of the membrane is small, and the function of passivation is insufficient. In addition, a positive fixed charge is shown. The passivation film obtained from the passivation material (d-3) has a negative fixed charge, but its value is small. In addition, the carrier lifetime is relatively small, and the function of passivation is insufficient.

[Reference Examples 1-6]

A solar cell element having the structure shown in Fig. 8 was produced by using a single crystal germanium substrate doped with boron as the germanium substrate 101. After the surface of the ruthenium substrate 101 is subjected to a texture treatment, a coating-type phosphorus diffusion material is applied to the light-receiving surface side, and a diffusion layer 102 (phosphorus diffusion layer) is formed by heat treatment. Thereafter, the coated phosphorus diffusion material was removed using dilute hydrofluoric acid.

Then, an SiN film formed by plasma CVD is formed on the light-receiving surface side as the light-receiving surface anti-reflection film 103. Thereafter, the passivation material (a-1) prepared in Reference Example 1-1 was applied to a region other than the contact region (opening portion OA) in the back surface side of the ruthenium substrate 101 by an inkjet method. Thereafter, heat treatment is performed to form a passivation film 107 having an opening OA.

Further, as the passivation film 107, a sample using the passivation material (c-1) prepared in Reference Example 1-3 was also prepared.

Then, on the light-receiving surface anti-reflection film 103 (SiN film) formed on the light-receiving surface side of the ruthenium substrate 101, a paste containing silver as a main component is screen-printed in the shape of a predetermined finger electrode and a bus bar electrode. On the back side, a paste with aluminum as a main component was screen printed onto the entire surface. Thereafter, heat treatment (burn-through) was performed at 850 ° C to form electrodes (the first electrode 105 and the second electrode 106), and aluminum was diffused into the portion of the opening OA of the back surface to form the BSF layer 104, and FIG. 8 was formed. The solar cell element of the structure shown.

In the silver electrode of the light-receiving surface, a burn-through step that does not open a hole in the SiN film is described. However, the opening portion OA may be formed in advance in the SiN film by etching or the like, and then a silver electrode may be formed.

For comparison, in the above-described fabrication step, the formation of the passivation film 107 is performed, and the aluminum paste is printed on the entire surface on the back side, and the p ⁺ layer 114 and the second electrode corresponding to the BSF layer 104 are formed on the entire surface. The corresponding electrode 116 forms a solar cell element having the structure shown in FIG. The solar cell elements were evaluated for characteristics (short circuit current, open circuit voltage, curve factor, and conversion efficiency). The evaluation of the characteristics was carried out in accordance with JIS-C-8913 (2005) and JIS-C-8914 (2005). The results are shown in Table 7.

As shown in Table 7, the solar cell element having the passivation film 107 containing the yttrium oxide and the aluminum oxide layer has an increase in the short-circuit current and the open-circuit voltage, and the conversion efficiency (photoelectric conversion efficiency) is the largest as compared with the solar cell element having no passivation film 107. Increase by 1%.

<Reference Embodiment 2>

The following is a passivation film, a coating type material, and a solar cell element according to the second embodiment. And a germanium substrate with a passivation film.

<1> A passivation film containing an oxide of at least one vanadium element selected from the group consisting of vanadium oxide and cerium oxide, and used in a solar cell element having a ruthenium substrate.

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

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

The passivation film according to any one of <1> to <3> containing an oxide of two or three kinds of vanadium elements selected from the group consisting of vanadium oxide, cerium oxide and cerium oxide. It is an oxide of the above-mentioned vanadium group element.

The passivation film according to any one of <1> to <4> which is a heat-treated material of a coating material containing a precursor of alumina and a precursor selected from vanadium oxide. A precursor of an oxide of at least one vanadium element in the group consisting of precursors of cerium oxide and cerium oxide.

<6> a coating type material comprising a precursor of an alumina, a precursor of an oxide of at least one vanadium element selected from the group consisting of a precursor of vanadium oxide and a precursor of cerium oxide, and It is a passivation film for forming a solar cell element having a germanium substrate.

<7> A solar cell element comprising: a p-type germanium substrate; The n-type impurity diffusion layer is formed on the first surface side as the light-receiving surface side of the germanium substrate; the first electrode is formed on the impurity diffusion layer; and the passivation film is formed on the opposite side of the light-receiving surface of the germanium substrate a second surface having an opening; and a second electrode formed on the second surface side of the ruthenium substrate, and electrically connected to the second surface side of the ruthenium substrate via the opening of the passivation film; and the passivation film An oxide comprising at least one vanadium element selected from the group consisting of alumina and vanadium oxide and cerium oxide.

<8> The solar cell element according to <7>, which has a p-type impurity diffusion layer formed on a part or all of the second surface side of the tantalum substrate, and is larger than the tantalum substrate Impurities are added to a higher concentration, and the second electrode is electrically connected to the p-type impurity diffusion layer through an opening of the passivation film.

<9> A solar cell element comprising: an n-type germanium substrate; a p-type impurity diffusion layer formed on a first surface side of the light-receiving surface side of the germanium substrate; a first electrode formed on the impurity diffusion layer; and passivation a film formed on the second surface side opposite to the light-receiving surface side of the ruthenium substrate and having an opening; and a second electrode formed on the second surface side of the ruthenium substrate via the passivation The opening of the film is electrically connected to the second surface side of the germanium substrate; and the passivation film contains an oxide of at least one vanadium group element selected from the group consisting of vanadium oxide and cerium oxide.

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

The solar cell element according to any one of the above aspects, wherein the mass ratio of the oxide of the vanadium group element to the aluminum oxide in the passivation film is 30/70 to 90/10.

The solar cell element according to any one of the above aspects of the present invention, wherein the total content of the oxide of the vanadium group element and the aluminum oxide of the passivation film is 90% or more.

The solar cell element according to any one of <7> to <12> containing oxidation of two or three kinds of vanadium elements selected from the group consisting of vanadium oxide, cerium oxide and cerium oxide. The substance acts as an oxide of the above vanadium group element.

<14> A solar cell element according to any one of <1> to <5>, wherein: Passivation film.

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

The passivation film of the present embodiment is a passivation film used in a tantalum solar cell element, and contains an oxide of at least one vanadium group element selected from the group consisting of alumina oxide and cerium oxide.

Further, in the present embodiment, the amount of the fixed charge which the passivation film has can be controlled by changing the composition of the passivation film. Here, the vanadium group element refers to a group 5 element of the periodic table of elements, and is an element selected from the group consisting of vanadium, niobium and tantalum.

Further, from the viewpoint of stabilizing the negative fixed charge, the mass ratio of the oxide of the vanadium element to the alumina is preferably 35/65 to 90/10, and more preferably 50/50 to 90/10.

The mass ratio of the oxide of the vanadium group element to the aluminum oxide in the passivation film can be determined by energy dispersive X-ray spectroscopy (EDX), secondary ion mass spectrometry (SIMS), and high frequency inductively coupled plasma mass spectrometry ( ICP-MS) to determine. The specific measurement conditions are as follows, for example, in the case of ICP-MS. Dissolving the passivation film in an acid or alkaline aqueous solution, forming the solution into a mist and introducing it into the Ar plasma, and splitting the light emitted by the excited element back to the ground state to measure the wavelength and intensity, according to the obtained The wavelength is used to characterize the element, and the amount is quantified based on the obtained intensity.

The total content of oxides and alumina of vanadium elements in passivation film is higher The amount is preferably 80% by mass or more, and more preferably 90% by mass or more from the viewpoint of maintaining good characteristics. When the oxide of the vanadium group element and the components other than the alumina in the passivation film are increased, the effect of negatively fixing the charge becomes large.

Further, in the passivation film, from the viewpoint of improving the film quality and adjusting the elastic modulus, an oxide other than a vanadium element and a component other than alumina can be contained as an organic component. The presence of the organic component in the passivation film can be confirmed by elemental analysis and Fourier transform infrared spectroscopy (FT-IR) measurement of the film.

From the viewpoint of obtaining a larger negative fixed charge, the oxide of the above-mentioned vanadium element is preferably selected from vanadium oxide (V ₂ O ₅ ).

The passivation film may further contain, as an oxide of a vanadium group element, an oxide of two or three kinds of vanadium elements selected from the group consisting of vanadium oxide, cerium oxide, and cerium oxide.

The passivation film is preferably obtained by heat-treating a coating type material, and is more preferably obtained by coating a coating type material by a coating method or a printing method, and thereafter by heat treatment. Organic ingredients are removed. That is, the passivation film can also be obtained as a heat-treated product of a coating material containing a precursor of an oxide of an alumina precursor and an oxide of a vanadium group. The details of the coating material will be described later.

The coating material of the present embodiment is a coating material used for a passivation film for a solar cell element having a ruthenium substrate, and contains a precursor of alumina and a precursor selected from a precursor of vanadium oxide and ruthenium oxide. A precursor of an oxide of at least one vanadium element in the group formed. From the viewpoint of the negative fixed charge of the passivation film formed of the coating material, the precursor of the oxide of the vanadium element contained in the coating type material is preferably a precursor of selecting vanadium oxide (V ₂ O ₅ ). . The coating material may also contain a precursor of an oxide of two or three kinds of vanadium elements selected from the group consisting of a precursor of vanadium oxide, a precursor of cerium oxide, and a precursor of cerium oxide as a vanadium group. The precursor of the oxide of the element.

The alumina precursor can be used without particular limitation as long as it forms alumina. From the viewpoint of uniformly dispersing alumina on the ruthenium substrate and chemical stability, the alumina precursor is preferably an organic alumina precursor. Examples of the organic alumina precursors include 1,3-Misopropoxide (structural formula: Al(OCH(CH ₃ ) ₂ ) ₃ ), and SYM-AL04 of the Institute of High Purity Chemicals.

The precursor of the oxide of the vanadium group element can be used without particular limitation as long as it forms an oxide of a vanadium group element. The precursor of the oxide of the vanadium group element is preferably a precursor of an oxide of an organic vanadium group element from the viewpoint of uniformly dispersing the alumina on the tantalum substrate and chemical stability.

Examples of the organic vanadium oxide precursor include vanadium oxyacetate (V) (structural formula: VO(OC ₂ H ₅ ) ₃ , molecular weight: 202.13), and V- of the High Purity Chemical Research Institute (share). 02. Examples of the precursor of the organic cerium oxide include methanol oxime (V) (structural formula: Ta(OCH ₃ ) ₅ , molecular weight: 336.12), and Ta-10-P of the High Purity Chemical Research Institute. Examples of the organic cerium oxide precursor include cerium (V) (structural formula: Nb(OC ₂ H ₅ ) ₅ , molecular weight: 318.21), and Nb-05 of the High Purity Chemical Research Institute.

Oxidation of vanadium-containing elements containing organic systems by coating or printing A coating material of a precursor of the substance and an organic alumina precursor is formed into a film, and the organic component is removed by heat treatment thereafter, whereby a passivation film can be obtained. Therefore, the passivation film can also be a passivation film containing an organic component. The content of the organic component in the passivation film is preferably less than 10% by mass, more preferably 5% by mass or less, and still more preferably 1% by mass or less.

The solar cell element (photoelectric conversion device) of the present embodiment has the passivation film (insulating film, protective insulating film) described in the above embodiment in the vicinity of the photoelectric conversion interface of the germanium substrate, that is, contains alumina and is selected from vanadium oxide. And a film of an oxide of at least one vanadium element in the group consisting of cerium oxide. By using an oxide containing at least one vanadium element selected from the group consisting of alumina and vanadium oxide and cerium oxide, the carrier life of the ruthenium substrate can be extended and a negative fixed charge can be obtained, thereby improving solar cell elements. Characteristics (photoelectric conversion efficiency).

The description of the structure and the manufacturing method of the solar cell element of the present embodiment can be referred to the description of the structure and the manufacturing method of the solar cell element according to the first embodiment.

Hereinafter, the reference embodiment and the reference comparative example of the present embodiment will be described in detail.

<Case of using vanadium oxide as an oxide of a vanadium group element>

[Reference Example 2-1]

A commercially available organometallic thin film coating type material which can obtain alumina (Al ₂ O ₃ ) by heat treatment (calcination) [High Purity Chemical Research Institute, SYM-AL04, concentration: 2.3% by mass] 3.0 g, a commercially available organometallic thin film coating type material capable of obtaining vanadium oxide (V ₂ O ₅ ) by heat treatment (calcination) [High Purity Chemical Research Institute, V-02, concentration 2% by mass ] 6.0 g of a mixture was used to prepare a passivation material (a2-1) as a coating type material.

The passivation material (a2-1) was spin-coated on a 8-inch p-type tantalum substrate (8 Ω.cm to 12 Ω.cm) having a thickness of 725 μm of a natural oxide film removed by using hydrofluoric acid having a concentration of 0.49% by mass in advance. On one side, it was placed on a hot plate and prebaked at 120 ° C for 3 minutes. Thereafter, heat treatment (calcination) was performed at 700 ° C for 30 minutes in a nitrogen atmosphere to obtain a passivation film containing alumina and vanadium oxide [vanadium oxide / alumina = 63 / 37 (% by mass)]. The film thickness was measured by an ellipsometer and found to be 51 nm. The FT-IR of the passivation film was measured, and as a result, a very weak peak derived from an alkyl group was observed in the vicinity of 1200 cm ^-1 .

Then, on the passivation film, a plurality of aluminum electrodes having a diameter of 1 mm were formed by vapor deposition to form a capacitor of a metal-insulator-semiconductor (MIS) structure. The voltage dependence (CV characteristic) of the capacitance of the capacitor was measured by a commercially available prober and an LCR meter (HP company, 4275A). The results show that the flat band voltage (Vfb) is shifted from the ideal value of -0.81V to +0.02V. From the amount of movement, it was found that the passivation film obtained from the passivation material (a2-1) exhibited a fixed charge having a fixed charge density (Nf) of -5.2 × 10 ¹¹ cm ^-2 and a negative value.

In the same manner as described above, the passivation material (a2-1) was applied to both surfaces of a 8 Å p-type ruthenium substrate, prebaked, and heat-treated (calcined) at 650 ° C for 1 hour in a nitrogen atmosphere to prepare ruthenium. A sample covered by a passivation film on both sides of the substrate. Life measuring device (Kobelco Research Institute) (Unit), RTA-540) to determine the carrier lifetime of the sample. The resulting carrier lifetime was 400 μs. For comparison, the same 8-inch p-type ruthenium substrate was passivated and measured by iodine passivation, and the carrier lifetime was 1100 μs. Further, after 14 days from the preparation of the sample, the carrier life was measured again, and as a result, the carrier lifetime was 380 μs. From this, it was found that the decrease in carrier lifetime (400 μs to 380 μs) was within -10%, and the decrease in carrier lifetime was small.

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

[Reference Example 2-2]

In the same manner as in Reference Example 2-1, a commercially available organometallic thin film coating type material (High Purity Chemical Research Institute, SYM) which can obtain alumina (Al ₂ O ₃ ) by heat treatment (calcination) is used. -AL04, a concentration of 2.3% by mass], and a commercially available organometallic thin film coating type material capable of obtaining vanadium oxide (V ₂ O ₅ ) by heat treatment [High Purity Chemical Research Institute, V-02, The passivation material (a2-2) to the passivation material (a2-7) shown in Table 8 were prepared by mixing at a concentration of 2% by mass.

In the same manner as in Reference Example 2-1, the passivation material (a2-2) to the passivation material (a2-7) were respectively applied onto one surface of the p-type germanium substrate, and heat-treated (calcined) to prepare a passivation film. The voltage dependence of the capacitance of the obtained passivation film was measured, and the fixed charge density was calculated based on this.

Then, in the same manner as in Reference Example 2-1, a passivation material was applied onto both surfaces of the p-type ruthenium substrate, and heat treatment (calcination) was carried out, and the obtained sample was used for measurement. Carrier life.

The results obtained are summarized in Table 8. Further, after 14 days from the preparation of the sample, the carrier life was measured again, and as a result, the carrier lifetime of the passivation film using the passivation material (a2-2) to the passivation material (a2-7) shown in Table 8 was reduced - Within 10%, the decrease in carrier lifetime is small.

Depending on the ratio (mass ratio) of vanadium oxide/alumina after heat treatment (calcination), the results are different, but the passivation material (a2-2) to passivation material (a2-7) show a negative fixation after heat treatment (calcination). The charge and carrier lifetime also show a certain degree of value, so it is suggested to function as a passivation film. It is known that the passivation film obtained from the passivation material (a2-2) to the passivation material (a2-7) stably exhibits a negative fixed charge, and can also be preferably used as a passivation film of a p-type germanium substrate.

[Reference Example 2-3]

Commercially available vanadium oxyacetate (V) as a compound which can be obtained by heat treatment (calcination) to obtain vanadium oxide (V ₂ O ₅ ) (structural formula: VO(OC ₂ H ₅ ) ₃ , molecular weight: 202.13) 1.02 g (0.010 mol), and commercially available triisopropoxy aluminum as a compound which can be obtained by heat treatment (calcination) to obtain alumina (Al ₂ O ₃ ) (structural formula: Al(OCH(CH ₃ ) ₂ ) ₃ , Molecular weight: 204.25) 2.04 g (0.010 mol) was dissolved in 60 g of cyclohexane to prepare a passivation material (b2-1) having a concentration of 5% by mass.

The passivation material (b2-1) was spin-coated on a 8-inch p-type tantalum substrate (8 Ω.cm to 12 Ω.cm) having a thickness of 725 μm of a natural oxide film removed by using hydrofluoric acid having a concentration of 0.49% by mass in advance. On one side, prebaking was carried out on a hot plate at 120 ° C for 3 minutes. Thereafter, heat treatment (calcination) was performed at 650 ° C for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and vanadium oxide. The film thickness was measured by an ellipsometer and found to be 60 nm. As a result of elemental analysis, it was found that V/Al/C = 64/33/3 (% by mass). The FT-IR of the passivation film was measured, and as a result, a very weak peak derived from an alkyl group was observed in the vicinity of 1200 cm ^-1 .

Then, on the passivation film, a plurality of aluminum electrodes having a diameter of 1 mm were formed by vapor deposition to form a capacitor of a metal-insulator-semiconductor (MIS) structure. The voltage dependence (CV characteristic) of the capacitance of the capacitor was measured by a commercially available prober and an LCR meter (HP company, 4275A). The results show that the flat band voltage (Vfb) is shifted from the ideal value of -0.81V to +0.10V. From the amount of movement, it was found that the passivation film obtained from the passivation material (b2-1) showed a fixed charge having a fixed charge density (Nf) of -6.2 × 10 ¹¹ cm ^-2 and a negative value.

The passivation material (b2-1) was applied to both surfaces of a 8-inch p-type tantalum substrate in the same manner as described above, prebaked, and heat-treated (calcined) at 600 ° C for 1 hour in a nitrogen atmosphere to prepare a crucible. A sample covered by a passivation film on both sides of the substrate. borrow The carrier life of the sample was measured by a life measuring device (Kobelco Research Institute, RTA-540). The resulting carrier lifetime was 400 μs. For comparison, the same 8-inch p-type ruthenium substrate was passivated and measured by iodine passivation, and the carrier lifetime was 1100 μs.

From the above, it is known that the passivation film obtained by subjecting the passivation material (b2-1) to heat treatment (calcination) exhibits a certain degree of passivation performance and exhibits a negative fixed charge.

[Reference Example 2-4]

Commercially available vanadium oxyacetate (V) (structural formula: VO(OC ₂ H ₅ ) ₃ , molecular weight: 202.13) 1.52 g (0.0075 mol), commercially available triisopropoxy aluminum (structural formula: Al (OCH(CH ₃ ) ₂ ) ₃ , molecular weight: 204.25) 1.02 g (0.005 mol), and 10 g of novolac resin were dissolved in 10 g of diethylene glycol monobutyl ether acetate and 10 g of cyclohexane to prepare a passivation material ( B2-2).

The passivation material (b2-2) was spin-coated on a 8-inch p-type tantalum substrate (8 Ω.cm to 12 Ω.cm) having a thickness of 725 μm of a natural oxide film removed by using hydrofluoric acid having a concentration of 0.49% by mass in advance. On one side, it was placed on a hot plate and prebaked at 120 ° C for 3 minutes. Thereafter, the film was heated at 650 ° C for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and vanadium oxide. The film thickness was measured by an ellipsometer and found to be 22 nm. As a result of elemental analysis, it was found that V/Al/C = 71/22/7 (% by mass). The FT-IR of the passivation film was measured, and as a result, a very weak peak derived from an alkyl group was observed in the vicinity of 1200 cm ^-1 .

Then, on the passivation film, a plurality of aluminum electrodes having a diameter of 1 mm were formed by vapor deposition to form a capacitor of a metal-insulator-semiconductor (MIS) structure. The voltage dependence (CV characteristic) of the capacitance of the capacitor was measured by a commercially available prober and an LCR meter (HP company, 4275A). The results show that the flat band voltage (Vfb) is shifted from the ideal value of -0.81V to +0.03V. From the amount of movement, it was found that the passivation film obtained from the passivation material (b2-2) exhibited a fixed charge having a fixed charge density (Nf) of -2.0 × 10 ¹¹ cm ^-2 and a negative value.

In the same manner as described above, the passivation material (b2-2) was applied onto both surfaces of a 8 Å p-type ruthenium substrate, prebaked, and heat-treated (calcined) at 600 ° C for 1 hour in a nitrogen atmosphere to prepare. A sample covered by a passivation film on both sides of the substrate. The carrier life of the sample was measured by a life measuring device (Kobelco Research Institute, RTA-540). The resulting carrier lifetime was 170 μs. For comparison, the same 8-inch p-type ruthenium substrate was passivated and measured by iodine passivation, and the carrier lifetime was 1100 μs.

From the above, it is known that the passivation film obtained by hardening the passivation material (b2-2) exhibits a certain degree of passivation performance and exhibits a negative fixed charge.

<Case of using cerium oxide as an oxide of a vanadium group element>

[Reference Example 2-5]

A commercially available organometallic thin film coating type material (high purity chemical research institute, SYM-AL04, concentration: 2.3% by mass) which can obtain alumina (Al ₂ O ₃ ) by heat treatment (calcination), A ratio of change in a commercially available organometallic thin film coating type material (high purity chemical research institute, Ta-10-P, concentration: 10% by mass) which can be obtained by heat treatment to obtain cerium oxide (Ta ₂ O ₅ ) While mixing, the passivation material (c2-1) to passivation material (c2-6) shown in Table 9 was prepared.

The passivation material (c2-1) to the passivation material (c2-6) were spin-coated on the 8-inch p-type germanium substrate having a thickness of 725 μm in which the natural oxide film was removed by using hydrofluoric acid having a concentration of 0.49% by mass in advance ( One side of 8 Ω.cm~12 Ω.cm) was placed on a hot plate and pre-baked at 120 ° C for 3 minutes. Thereafter, heat treatment (calcination) was performed at 700 ° C for 30 minutes in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and cerium oxide. The passivation film was used to measure the voltage dependence of the electrostatic capacitance, and the fixed charge density was calculated based on this.

Then, the passivation material (c2-1) to the passivation material (c2-6) were respectively applied to both surfaces of a 8 Å p-type ruthenium substrate, prebaked, and subjected to a nitrogen atmosphere at 650 ° C for 1 hour. Heat treatment (calcination), and a sample covered with a passivation film on both sides of the tantalum substrate was prepared. The carrier life of the sample was measured by a life measuring device (Kobelco Research Institute, RTA-540).

The results obtained are summarized in Table 9. Further, after 14 days from the preparation of the sample, the carrier lifetime was measured again, and as a result, it was found that the carrier lifetime of the passivation film using the passivation material (c2-1) to the passivation material (c2-6) shown in Table 9 was lowered. Within -10%, the decrease in carrier lifetime is small.

Depending on the ratio (mass ratio) of cerium oxide/alumina after heat treatment (calcination), the results are different, but the passivation material (c2-1) to passivation material (c2-6) show negative fixation after heat treatment (calcination). Charge, carrier lifetime also shows some degree The value is therefore revealed to function as a passivation film.

[Reference Example 2-6]

Commercially available methanol oxime (V) (structure: Ta(OCH ₃ ) ₅ , molecular weight: 336.12) 1.18 g (0.0025 mol) as a compound capable of obtaining cerium oxide (Ta ₂ O ₅ ) by heat treatment (calcination) And commercially available triisopropoxy aluminum as a compound which can be obtained by heat treatment (calcination) to obtain alumina (Al ₂ O ₃ ) (structural formula: Al(OCH(CH ₃ ) ₂ ) ₃ , molecular weight: 204.25) 2.04 g (0.010 mol) was dissolved in 60 g of cyclohexane to prepare a passivation material (d2-1) having a concentration of 5% by mass.

The passivation material (d2-1) was spin-coated on a 8-inch p-type tantalum substrate (8 Ω.cm to 12 Ω.cm) having a thickness of 725 μm of a natural oxide film removed by using hydrofluoric acid having a concentration of 0.49% by mass in advance. On one side, it was placed on a hot plate and prebaked at 120 ° C for 3 minutes. Thereafter, the film was heated at 700 ° C for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and cerium oxide. The film thickness was measured by an ellipsometer and found to be 40 nm. As a result of elemental analysis, it was found that Ta/Al/C = 75/22/3 (wt%). The FT-IR of the passivation film was measured, and as a result, a very weak peak derived from an alkyl group was observed in the vicinity of 1200 cm ^-1 .

Then, on the passivation film, a plurality of aluminum electrodes having a diameter of 1 mm were formed by vapor deposition to form a capacitor of a metal-insulator-semiconductor (MIS) structure. The voltage dependence (CV characteristic) of the capacitance of the capacitor was measured by a commercially available prober and an LCR meter (HP company, 4275A). The results show that the flat band voltage (Vfb) is shifted from the ideal value of -0.81V to -0.30V. From the amount of movement, it was found that the passivation film obtained from the passivation material (d2-1) showed a fixed charge having a fixed charge density (Nf) of -6.2 × 10 ¹⁰ cm ^-2 and a negative value.

In the same manner as described above, the passivation material (d2-1) was applied to both surfaces of a 8 Å p-type ruthenium substrate, prebaked, and heat-treated (calcined) at 600 ° C for 1 hour in a nitrogen atmosphere to prepare ruthenium. A sample covered by a passivation film on both sides of the substrate. The carrier life of the sample was measured by a life measuring device (Kobelco Research Institute, RTA-540). The resulting carrier lifetime was 610 μs. For comparison, the same 8-inch p-type ruthenium substrate was passivated and measured by iodine passivation, and the carrier lifetime was 1100 μs.

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

[Reference Examples 2-7]

Commercially available methanol oxime (V) (structure: Ta(OCH ₃ ) ₅ , molecular weight: 336.12) 1.18 g (0.005 mol) as a compound capable of obtaining cerium oxide (Ta ₂ O ₅ ) by heat treatment (calcination) As a commercially available compound of aluminum oxide (Al ₂ O ₃ ) which can be obtained by heat treatment (calcination), aluminum triisopropoxide (structural formula: Al(OCH(CH ₃ ) ₂ ) ₃ , molecular weight: 204.25 1.02 g (0.005 mol) and 10 g of a novolac resin were dissolved in a mixture of 10 g of diethylene glycol monobutyl ether acetate and 10 g of cyclohexane to prepare a passivation material (d2-2).

The passivation material (d2-2) was spin-coated on a 8-inch p-type ruthenium substrate (8 Ω.cm to 12 Ω.cm) having a thickness of 725 μm of a natural oxide film removed by using hydrofluoric acid having a concentration of 0.49% by mass in advance. On one side, prebaking was carried out on a hot plate at 120 ° C for 3 minutes. Thereafter, the film was heated at 650 ° C for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and cerium oxide. The film thickness was measured by an ellipsometer and found to be 18 nm. As a result of elemental analysis, it was found that Ta/Al/C = 72/20/8 (wt%). The FT-IR of the passivation film was measured, and as a result, a very weak peak derived from an alkyl group was observed in the vicinity of 1200 cm ^-1 .

Then, on the passivation film, a plurality of aluminum electrodes having a diameter of 1 mm were formed by vapor deposition to form a capacitor of a metal-insulator-semiconductor (MIS) structure. The voltage dependence (CV characteristic) of the capacitance of the capacitor was measured by a commercially available prober and an LCR meter (HP company, 4275A). The results show that the flat band voltage (Vfb) is shifted from the ideal value of -0.81V to -0.43V. From the amount of movement, it was found that the passivation film obtained from the passivation material (d-2) showed a fixed charge having a fixed charge density (Nf) of -5.5 × 10 ¹⁰ cm ^-2 and a negative value.

The passivation material (d2-2) was applied to both surfaces of a 8 Å p-type ruthenium substrate in the same manner as above, prebaked, and subjected to a nitrogen atmosphere at 600 ° C for 1 hour. The heat treatment (calcination) was performed to prepare a sample covered by a passivation film on both sides of the tantalum substrate. The carrier life of the sample was measured by a life measuring device (Kobelco Research Institute, RTA-540). The resulting carrier lifetime was 250 μs. For comparison, the same 8-inch p-type ruthenium substrate was passivated and measured by iodine passivation, and the carrier lifetime was 1100 μs.

From the above, it is known that the passivation film obtained by subjecting the passivation material (d2-2) to heat treatment (calcination) exhibits a certain degree of passivation performance and exhibits a negative fixed charge.

<Case of using two or more oxides of vanadium elements>

[Reference Example 2-8]

A commercially available organometallic thin film coating type material (high purity chemical research institute, SYM-AL04, concentration: 2.3% by mass) which can obtain alumina (Al ₂ O ₃ ) by heat treatment (calcination), A commercially available organometallic thin film coating type material capable of obtaining vanadium oxide (V ₂ O ₅ ) by heat treatment (calcination) [High Purity Chemical Research Institute, V-02, concentration: 2% by mass], and A commercially available organometallic thin film coating type material obtained by heat treatment (calcination) of lanthanum oxide (Ta ₂ O ₅ ) [High Purity Chemical Research Institute, Ta-10-P, concentration: 10% by mass] The passivation material (e2-1) as a coating type material was prepared by mixing (refer to Table 10).

A commercially available organometallic thin film coating type material (high purity chemical research institute, SYM-AL04, concentration: 2.3% by mass) which can obtain alumina (Al ₂ O ₃ ) by heat treatment (calcination), A commercially available organometallic thin film coating type material capable of obtaining vanadium oxide (V ₂ O ₅ ) by heat treatment (calcination) [High Purity Chemical Research Institute, V-02, concentration: 2% by mass], and A commercially available organometallic thin film coating type material (high purity chemical research institute, Nb-05, concentration: 5% by mass) which can obtain cerium oxide (Nb ₂ O ₅ ) by heat treatment (calcination), A passivation material (e2-2) as a coating type material was prepared (refer to Table 10).

A commercially available organometallic thin film coating type material (high purity chemical research institute, SYM-AL04, concentration: 2.3% by mass) which can obtain alumina (Al ₂ O ₃ ) by heat treatment (calcination), A commercially available organometallic thin film coating type material obtained by heat treatment (calcination) of lanthanum oxide (Ta ₂ O ₅ ) [High Purity Chemical Research Institute, Ta-10-P, concentration: 10% by mass] And a commercially available organometallic thin film coating type material which can obtain cerium oxide (Nb ₂ O ₅ ) by heat treatment (calcination) [High Purity Chemical Research Institute, Nb-05, concentration: 5% by mass] The passivation material (e2-3) as a coating type material was prepared by mixing (refer to Table 10).

A commercially available organometallic thin film coating type material (high purity chemical research institute, SYM-AL04, concentration: 2.3% by mass) which can obtain alumina (Al ₂ O ₃ ) by heat treatment (calcination), A commercially available organometallic thin film coating type material capable of obtaining vanadium oxide (V ₂ O ₅ ) by heat treatment (calcination) [High Purity Chemical Research Institute, V-02, concentration: 2% by mass], A commercially available organometallic thin film coating type material obtained by heat treatment (calcination) of lanthanum oxide (Ta ₂ O ₅ ) [High Purity Chemical Research Institute, Ta-10-P, concentration: 10% by mass], And a commercially available organometallic thin film coating type material (high purity chemical research institute, Nb-05, concentration: 5% by mass) which can obtain cerium oxide (Nb ₂ O ₅ ) by heat treatment (calcination) A passivation material (e2-4) as a coating type material was prepared (refer to Table 10).

The passivation material (e2-1) to the passivation material (e2-4) were spin-coated in the same manner as in Reference Example 2-1, respectively, and the thickness of the natural oxide film was 725 μm by using hydrofluoric acid having a concentration of 0.49% by mass in advance. On one side of a 8 inch p-type ruthenium substrate (8 Ω.cm to 12 Ω.cm), it was placed on a hot plate and prebaked at 120 ° C for 3 minutes. Thereafter, heat treatment (calcination) was performed at 650 ° C for 1 hour in a nitrogen atmosphere to obtain a passivation film containing an oxide of alumina and two or more kinds of vanadium group elements.

The voltage dependence of the electrostatic capacitance was measured using the passivation film obtained above, and the fixed charge density was calculated based on this.

Then, the passivation material (e2-1) to the passivation material (e2-4) were respectively applied to both surfaces of a 8 Å p-type ruthenium substrate, prebaked, and subjected to a nitrogen atmosphere at 650 ° C for 1 hour. Heat treatment (calcination), and a sample covered with a passivation film on both sides of the tantalum substrate was prepared. The carrier life of the sample was measured by a life measuring device (Kobelco Research Institute, RTA-540).

The results obtained are summarized in Table 10.

Depending on the ratio (mass ratio) of oxides of two or more kinds of vanadium elements after heat treatment (calcination), the results are different, but passivation using passivation material (e2-1) to passivation material (e2-4) The film showed a negative fixed charge after heat treatment (calcination), and the carrier lifetime also showed a certain value, so it was suggested to function as a passivation film.

[Reference Example 2-9]

In the same manner as in Reference Example 2-1, a commercially available organometallic thin film coating type material (High Purity Chemical Research Institute, SYM) which can obtain alumina (Al ₂ O ₃ ) by heat treatment (calcination) is used. -AL04, a concentration of 2.3% by mass], a commercially available organometallic thin film coating type material capable of obtaining vanadium oxide (V ₂ O ₅ ) by heat treatment (calcination) [High Purity Chemical Research Institute, V- 02, a concentration of 2% by mass], or a commercially available organometallic thin film coating type material which can obtain cerium oxide (Ta ₂ O ₅ ) by heat treatment (calcination) [High Purity Chemical Research Institute, Ltd., Ta- 10-P, a concentration of 10% by mass] was mixed, and a passivation material (f2-1) to passivation material (f2-8) as a coating material was prepared (refer to Table 10).

Further, a passivation material (f2-9) using alumina alone was prepared (refer to Table 11).

In the same manner as in Reference Example 2-1, the passivation material (f2-1) to the passivation material (f2-9) were applied to one surface of the p-type germanium substrate, respectively, and then heat-treated (calcined) to prepare a passivation film. Using the passivation film to measure the voltage dependence of the electrostatic capacitance, Based on this, the fixed charge density is calculated.

Further, in the same manner as in Reference Example 2-1, the passivation material (f2-1) to the passivation material (f2-9) were respectively applied to both surfaces of the p-type germanium substrate, and heat treatment (calcination) was performed, and the obtained sample was used. To determine the carrier lifetime. The results obtained are summarized in Table 11.

As shown in Table 11, when the alumina/vanadium oxide or yttrium oxide in the passivation material is 90/10 and 80/20, the deviation of the value of the fixed charge density is large, and the negative fixed charge density cannot be stably obtained. However, it was confirmed that a negative fixed charge density can be achieved by using alumina and cerium oxide. It has been found that when a passivation material using alumina, vanadium oxide or yttrium oxide of 90/10 and 80/20 is measured by the CV method, it may become a passivation film which exhibits a positive fixed charge, and thus is not stably Showing a negative fixed charge. Further, a passivation film exhibiting a positive fixed charge can be used as a passivation film of an n-type germanium substrate. On the other hand, the passivation material (f2-9) in which the alumina reaches 100% by mass cannot obtain a negative fixed charge density.

[Reference Example 2-10]

A single crystal germanium substrate using boron as a dopant was used as the germanium substrate 101, and a solar cell element having the structure shown in Fig. 8 was produced. After the surface of the ruthenium substrate 101 is subjected to a texture treatment, only the coating-type phosphorus diffusion material is applied to the light-receiving surface side, and the diffusion layer 102 (phosphorus diffusion layer) is formed by heat treatment. Thereafter, the coated phosphorus diffusion material was removed using dilute hydrofluoric acid.

Then, on the light-receiving side, a SiN film is formed as a light-receiving surface anti-reflection film 103 by plasma CVD. Thereafter, the passivation material (a2-1) prepared in Reference Example 2-1 was applied to a region other than the contact region (opening portion OA) on the back side of the tantalum substrate 101 by an inkjet method. Thereafter, heat treatment is performed to form a passivation film 107 having an opening OA. Further, as the passivation film 107, a sample using the passivation material (c2-1) prepared in Reference Example 2-5 was separately prepared.

Then, the light-receiving surface formed on the light-receiving surface side of the ruthenium substrate 101 is anti-reflection On the film 103 (SiN film), a paste containing silver as a main component is screen-printed in the shape of a predetermined finger electrode and a bus bar electrode. On the back side, a paste with aluminum as a main component was screen printed onto the entire surface. Thereafter, heat treatment (burn-through) was performed at 850 ° C to form electrodes (the first electrode 105 and the second electrode 106), and aluminum was diffused into the portion of the opening OA of the back surface to form the BSF layer 104, and FIG. 8 was formed. The solar cell element of the structure shown.

Further, in the formation of the silver electrode on the light-receiving surface, a burn-through step in which the SiN film is not formed is described. However, the opening portion OA may be formed in advance in the SiN film by etching or the like, and then the silver electrode may be formed. .

For comparison, in the above-described fabrication step, the formation of the passivation film 107 is performed, and the aluminum paste is printed on the entire surface on the back side, and the p ⁺ layer 114 and the second electrode corresponding to the BSF layer 104 are formed on the entire surface. The corresponding electrode 116 forms the solar cell element of the structure of Fig. 5. The solar cell elements were evaluated for characteristics (short circuit current, open circuit voltage, curve factor, and conversion efficiency). The evaluation of the characteristics was carried out in accordance with JIS-C-8913 (2005) and JIS-C-8914 (2005). The results are shown in Table 12.

As shown in Table 12, the solar cell element having the passivation film 107 was increased in both the short-circuit current and the open-circuit voltage as compared with the solar cell element having no passivation film 107, and the conversion efficiency (photoelectric conversion efficiency) was increased by 0.6% at the maximum.

Japanese Patent Application No. 2012-160336, Japanese Patent Application No. 2012-218389, Japanese Patent Application No. 2013-011934, Japanese Patent Application No. 2013-040152, and Japanese Patent Application No. 2013-040153 All disclosures are incorporated herein by reference. All the documents, Japanese patent applications, and technical standards described in the present specification are incorporated herein by reference in the same manner as the following, which are specifically and separately described in the respective documents, Japanese Patent Applications, and The case where the standard is incorporated by reference.

1‧‧‧p-type semiconductor substrate

2‧‧‧n ⁺ type diffusion layer

3‧‧‧Anti-reflective film

4‧‧‧p ⁺ diffusion layer

5‧‧‧Back electrode

6‧‧‧ Passivation layer

7‧‧‧Lighted surface electrode

Claims (16)

A solar cell element comprising: a semiconductor substrate having a light receiving surface, a back surface and a side surface opposite to the light receiving surface; a light receiving surface electrode disposed on the light receiving surface; a back surface electrode disposed on the back surface; and a passivation layer disposed on the semiconductor layer At least one of the light-receiving surface, the back surface, and the side surface includes at least one compound selected from the group consisting of Nb ₂ O ₅ , Ta ₂ O _{5 ,} and V ₂ O ₅ . The solar cell element according to claim 1, wherein the passivation layer further contains Al ₂ O ₃ . The solar cell element according to the first or second aspect of the invention, wherein the passivation layer is a heat-treated material of a composition for forming a passivation layer. The solar cell element according to claim 3, wherein the passivation layer forming composition contains a metal oxide selected from the group consisting of Nb ₂ O ₅ , Ta ₂ O ₅ and V ₂ O ₅ and as the metal oxide At least one compound of the group consisting of the compounds represented by the following formula (I) of the precursor, M(OR ¹ ) _m (I) In the formula (I), M contains a group selected from Nb, Ta and V At least one metal element in the group consisting of; R ¹ each independently represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms; and m represents an integer of 0 to 5. The solar cell element according to claim 4, wherein the passivation layer forming composition contains a group selected from the group consisting of Nb ₂ O ₅ and a compound of the above formula (I) wherein M is Nb. The total content of the ruthenium compound in the composition for forming a passivation layer is at least one ruthenium compound, and is 0.1% by mass to 99.9% by mass in terms of Nb ₂ O ₅ . The solar cell element according to claim 3, wherein the passivation layer forming composition further contains at least a group selected from the group consisting of Al ₂ O ₃ and a compound represented by the following formula (II). An aluminum compound, In the formula (II), R ² each independently represents an alkyl group having 1 to 8 carbon atoms; n represents an integer of 0 to 3; and X ² and X ³ each independently represent an oxygen atom or a methylene group; and R ³ and R ^{4 ;} And R ⁵ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. The solar cell element according to claim 6, wherein R ² in the above formula (II) is independently an alkyl group having 1 to 4 carbon atoms. The solar cell element according to claim 6, wherein n in the above formula (II) is an integer of 1 to 3, and R ^{5 is} each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The solar cell element according to claim 6, wherein the passivation layer forming composition contains at least one aluminum selected from the group consisting of compounds represented by Al ₂ O ₃ and the above formula (II). In the compound, the content of the aluminum compound in the composition for forming a passivation layer is from 0.1% by mass to 80% by mass. The solar cell element according to claim 3, wherein the passivation layer forming composition further contains a liquid medium. The solar cell element according to claim 10, wherein the liquid medium contains a group selected from the group consisting of a hydrophobic organic solvent, an aprotic organic solvent, a terpene solvent, an ester solvent, an ether solvent, and an alcohol solvent. At least one of them. A method of manufacturing a solar cell element according to any one of claims 1 to 11, further comprising the step of forming a light-receiving surface electrode on a light-receiving surface of the semiconductor substrate a step of forming a back surface electrode on the back surface, wherein the back surface is a surface opposite to the light receiving surface of the semiconductor substrate, and a composition for forming a passivation layer is formed on at least one of the light receiving surface, the back surface, and the side surface to form a composition layer In the step, the passivation layer forming composition contains at least one compound selected from the group consisting of Nb ₂ O ₅ , Ta ₂ O ₅ , V ₂ O ₅ and a compound represented by the following formula (I); And a step of heat-treating the composition layer to form a passivation layer; M(OR ¹ ) _m (I) In the formula (I), M contains at least one metal selected from the group consisting of Nb, Ta, and V The element R ¹ independently represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms; and m represents an integer of 0 to 5. The method for producing a solar cell element according to claim 12, wherein the passivation layer forming composition further contains a group selected from the group consisting of Al ₂ O ₃ and a compound represented by the following formula (II). At least one aluminum compound, In the formula (II), R ² each independently represents an alkyl group having 1 to 8 carbon atoms; n represents an integer of 0 to 3; and X ² and X ³ each independently represent an oxygen atom or a methylene group; and R ³ and R ^{4 ;} And R ⁵ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. The method for producing a solar cell element according to claim 12, wherein the temperature of the heat treatment is 400 ° C or higher. The method for producing a solar cell element according to claim 12, wherein the step of forming the composition layer comprises: providing the composition for forming a passivation layer by a screen printing method or an inkjet method. A solar cell module according to any one of claims 1 to 11, and a wiring material disposed on an electrode of the solar cell element.