JP2015026666A - Double-sided light-receiving solar cell element, method for producing the same, and double-sided light-receiving solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell element which has excellent conversion efficiency and suppresses deterioration with time of the conversion efficiency, and a simple method for producing the same, and a solar cell module.SOLUTION: A double-sided light-receiving solar cell element has: a semiconductor substrate having a surface light-receiving face and a rear light-receiving face in an opposite side to the surface light-receiving face; a light-receiving surface electrode which is arranged on the surface light-receiving face and the rear light-receiving face; and a passivation layer which is arranged on at least one face of the surface light-receiving face, the rear light-receiving face and side faces in the semiconductor substrate, and contains at least one kind of a compound selected from a group consisting of NbO, TaO, VO, YOand HfO.

Description

  The present invention relates to a double-sided light receiving solar cell element, a method for manufacturing the same, and a method for manufacturing a double-sided light receiving solar cell module.

The manufacturing process of the conventional silicon solar cell element is demonstrated.
First, a p-type silicon substrate having a textured structure is prepared so as to promote the light confinement effect and achieve high efficiency, and subsequently, 800 ° C. to 900 ° C. in a mixed gas atmosphere of phosphorus oxychloride (POCl ₃ ), nitrogen and oxygen. An n-type diffusion layer is uniformly formed by performing several tens of minutes at a temperature. In this conventional method, since phosphorus is diffused using a mixed gas, n-type diffusion layers are formed not only on the surface but also on the side surface and the back surface. Therefore, side etching is performed to remove the n-type diffusion layer formed on the side surface. Further, the n-type diffusion layer formed on the back surface needs to be converted into a p ⁺ -type diffusion layer. For this reason, by applying an aluminum paste containing aluminum particles and a binder to the entire back surface and heat-treating (baking) it, the n-type diffusion layer is converted into a p ⁺ -type diffusion layer and an aluminum electrode is formed. Get ohmic contact.

  However, an aluminum electrode formed from an aluminum paste has low conductivity, and in order to reduce sheet resistance, an aluminum electrode generally formed on the entire back surface must have a thickness of about 10 to 20 μm after heat treatment (firing). Don't be. Furthermore, since the thermal expansion coefficient differs greatly between silicon and aluminum, a large internal stress is generated in the silicon substrate during the heat treatment (baking) and cooling, causing damage to crystal grain boundaries, increasing crystal defects, and warping. Cause.

  In order to solve this problem, a double-sided solar cell that does not use an aluminum paste has been developed. Since these materials do not use aluminum paste on the front and back surfaces, the above problems (stress due to heat treatment) are less likely to occur and damage is less likely to occur. (For example, see Patent Document 1).

Further, in the case of double-sided light reception in this way, it is necessary to suppress the recombination rate of minority carriers on each light-receiving surface. For this purpose, a SiO ₂ film or the like has been proposed as a passivation layer for the back surface (see, for example, Patent Document 2). As a passivation effect by forming such a SiO ₂ film, there is an effect of terminating the dangling bonds of silicon atoms in the back surface layer portion of the silicon substrate and reducing the surface state density causing recombination.

As another method of suppressing recombination of minority carriers, there is a method of reducing the minority carrier density by an electric field that generates fixed charges in the passivation layer. Such a passivation effect is generally called a field effect, and an aluminum oxide (Al ₂ O ₃ ) film or the like has been proposed as a material having a negative fixed charge (see, for example, Patent Document 3).
Such a passivation layer is generally formed by an ALD (Atomic Layer Deposition) method, a CVD (Chemical Vapor Depositon) method, or the like (see, for example, Non-Patent Document 1). Further, as a simple method for forming an aluminum oxide film on a semiconductor substrate, a sol-gel method has been proposed (see, for example, Non-Patent Documents 2 and 3).

Japanese Patent No. 4232597 Japanese Patent Laid-Open No. 2004-6565 Japanese Patent No. 4767110

Journal of Applied Physics, 104 (2008), 113703 Thin Solid Films, 517 (2009), 6327-6330 Chinese Physics Letters, 26 (2009), 088102

  Since the method described in Non-Patent Document 1 includes complicated manufacturing processes such as vapor deposition, it may be difficult to improve productivity. In addition, in the composition for forming a passivation layer used in the methods described in Non-Patent Documents 2 and 3, problems such as gelation occur with time, and it is difficult to say that the storage stability is sufficient.

  The present invention has been made in view of the above-described conventional problems, and has a double-sided light receiving solar cell element that has excellent conversion efficiency and suppresses a decrease in conversion efficiency over time, a simple manufacturing method thereof, and It is an object of the present invention to provide a thick double-sided light receiving type positive battery module.

Specific means for solving the above problems are as follows.
<1> a semiconductor substrate having a front light receiving surface and a back light receiving surface opposite to the front light receiving surface;
A light receiving surface electrode disposed on the front light receiving surface and the back light receiving surface;
A group consisting of Nb ₂ O ₅ , Ta ₂ O ₅ , V ₂ O ₅ , Y ₂ O _3, and HfO ₂ disposed on at least one of the front light receiving surface, the back light receiving surface, and the side surface of the semiconductor substrate. A passivation layer containing one or more compounds selected from:
A double-sided light-receiving solar cell element.

<2> The double-sided light receiving solar cell element according to <1>, wherein the passivation layer further contains Al ₂ O ₃ .

<3> The double-sided solar cell element according to <1> or <2>, wherein the passivation layer is a heat-treated product of the composition for forming a passivation layer.

<4> The composition for forming a passivation layer is composed of Nb ₂ O ₅ , Ta ₂ O ₅ , V ₂ O ₅ , Y ₂ O ₃ , HfO ₂ and a compound represented by the following general formula (I). The double-sided solar cell element according to <3>, which contains one or more selected compounds.
M (OR ¹ ) _m (I)
[In General 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 of 0 to 5. ]

<5> The composition for forming a passivation layer further contains at least one selected from the group consisting of Al ₂ O ₃ and a compound represented by the following general formula (II): <3> or <4> The double-sided light receiving solar cell element according to 1.

〔一般式（ＩＩ）中、Ｒ^２はそれぞれ独立して炭素数１〜８のアルキル基を表す。ｎは０〜３の整数を表す。Ｘ^２及びＸ^３はそれぞれ独立して酸素原子又はメチレン基を表す。Ｒ^３、Ｒ^４及びＲ^５はそれぞれ独立して水素原子又は炭素数１〜８のアルキル基を表す。〕

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

<6> The double-sided solar cell element according to <5>, wherein R ² in the general formula (II) is each independently an alkyl group having 1 to 4 carbon atoms.

<7> n in the general 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, according to <5> or <6>. Double-sided light receiving solar cell element.

<8> The composition for forming a passivation layer, wherein the composition for forming a passivation layer contains at least one aluminum compound selected from the group consisting of the compound represented by the general formula (II) and Al ₂ O _3. The double-sided solar cell element according to any one of <5> to <7>, wherein the content of the aluminum compound in the product is 0.1 to 80% by mass.

<9> The passivation layer forming composition contains one or more niobium compounds selected from the group consisting of Nb ₂ O ₅ and a compound in which M in the general formula (I) is Nb, and the passivation layer The double-sided light receiving type according to any one of <4> to <8>, wherein the total content of the niobium compound in the forming composition is 0.1 to 99.9% by mass in terms of Nb ₂ O _5. Solar cell element.

<10> The double-sided light-receiving solar cell element according to any one of <3> to <9>, wherein the composition for forming a passivation layer further contains a liquid medium.

<11> The double-sided solar cell element according to <10>, wherein the liquid medium includes at least one selected from a hydrophobic organic solvent, an aprotic organic solvent, a terpene solvent, an ester solvent, an ether solvent, and an alcohol solvent. .

<12> The solar cell element according to any one of <1> to <11>, wherein the density of the passivation layer is 1.0 to 10.0 g / cm ³ .

<13> The solar cell element according to any one of <1> to <12>, wherein an average thickness of the passivation layer is 5 nm to 50 μm.

<14> forming a light receiving surface electrode on the front light receiving surface and the back light receiving surface of the semiconductor substrate;
Nb ₂ O ₅ , Ta ₂ O ₅ , V ₂ O ₅ , Y ₂ O ₃ , HfO ₂ and the following general formula (I) are represented on at least one of the front light receiving surface, the back light receiving surface and the side surface. Forming a composition layer by applying a composition for forming a passivation layer containing one or more compounds selected from the group consisting of:
Heat-treating the composition layer to form a passivation layer;
The manufacturing method of the double-sided light reception type solar cell element which has this.
M (OR ¹ ) _m (I)
[In General 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 of 0 to 5. ]

<15> The composition for forming a passivation layer further includes one or more aluminum compounds selected from the group consisting of a compound represented by the following general formula (II) and Al ₂ O ₃ <14>. Manufacturing method of a double-sided light receiving solar cell element.

〔一般式（ＩＩ）中、Ｒ^２はそれぞれ独立して炭素数１〜８のアルキル基を表す。ｎは０〜３の整数を表す。Ｘ^２及びＸ^３はそれぞれ独立して酸素原子又はメチレン基を表す。Ｒ^３、Ｒ^４及びＲ^５はそれぞれ独立して水素原子又は炭素数１〜８のアルキル基を表す。〕

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

<16> The method for producing a double-sided solar cell element according to <14> or <15>, wherein the temperature of the heat treatment is 400 ° C. or higher.

<17> The step of forming the composition layer includes applying the passivation layer forming composition by a spin coating method, a screen printing method, or an ink jet method, according to any one of <14> to <16>. The manufacturing method of the double-sided light reception type solar cell element of description.

<18> The double-sided solar cell element according to any one of <1> to <13>,
A wiring material disposed on the electrode of the double-sided light-receiving solar cell element;
A solar cell module.

  ADVANTAGE OF THE INVENTION According to this invention, it can provide the double-sided light reception type solar cell element which has the outstanding conversion efficiency, and the time-dependent fall of conversion efficiency is suppressed, its manufacturing method, and a double-sided light reception type solar cell module. .

It is sectional drawing which shows typically an example of the manufacturing method of the double-sided light reception type solar cell element which has a passivation layer concerning this embodiment.

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

<Double-sided light receiving solar cell element>
The double-sided light receiving solar cell element of the present invention includes a semiconductor substrate having a front light receiving surface and a back light receiving surface opposite to the front light receiving surface, and a light receiving surface electrode disposed on the front light receiving surface and the back light receiving surface. And Nb ₂ O ₅ , Ta ₂ O ₅ , V ₂ O ₅ , Y ₂ O ₃ and HfO ₂ are disposed on at least one of the front light receiving surface, the back light receiving surface and the side surface of the semiconductor substrate. And a passivation layer containing one or more compounds selected from the group consisting of: The double-sided light receiving solar cell element may further include other components as necessary.

  A solar cell element having a passivation layer containing a specific metal oxide on at least one of the front light-receiving surface, the back light-receiving surface, and the side surface of the semiconductor substrate has excellent conversion efficiency, and the conversion efficiency with time decreases with time. It is suppressed. This is considered to be because, for example, since the passivation layer contains a specific metal oxide, an excellent passivation effect is exhibited and the lifetime of carriers in the semiconductor substrate is extended, so that high efficiency can be achieved. Moreover, it is thought that by having the passivation layer containing the specific metal oxide, the passivation effect is maintained, and a decrease in conversion efficiency over time can be suppressed. Here, the deterioration of the solar cell characteristics over time can be evaluated by the solar cell characteristics after being left for a predetermined time in a constant temperature and humidity chamber.

  The reason why the passivation layer containing a specific metal oxide on at least one of the front light receiving surface, the back light receiving surface and the side surface of the semiconductor substrate has an excellent passivation effect can be considered as follows. That is, by providing a passivation layer containing a specific metal oxide on the surface of the semiconductor substrate, a fixed charge is generated near the interface with the semiconductor substrate due to defects of a specific metal element or oxygen atom in the specific metal oxide. Is considered to exist. This fixed charge generates an electric field in the vicinity of the interface of the semiconductor substrate, so that band bending occurs and the concentration of minority carriers can be reduced. As a result, since the carrier recombination rate at the interface is suppressed, it is considered that an excellent passivation effect is exhibited.

The fixed charge possessed by the specific metal oxide can be evaluated by a CV method (Capacitance Voltage measurement). When the surface state density of a passivation layer formed by heat-treating a composition for forming a passivation layer, which will be described later, is evaluated by a CV method, the value is larger than that of a passivation layer formed by an ALD method or a CVD method. There is. However passivation layer having the bifacial solar cell of the present invention is to decrease the electric field effect concentration of greater minority carriers, surface lifetime tau _s increases. Therefore, the surface state density is not a relative problem.

  In this specification, the passivation effect of a semiconductor substrate refers to the effective lifetime of minority carriers in a semiconductor substrate on which a passivation layer is formed using a reflection microwave conduction attenuation using a device such as WT-2000PVN manufactured by Nippon Semi-Lab Co., Ltd. It can be evaluated by measuring by the method.

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

1 / τ = 1 / τ _b + 1 / τ _s (A)

  Note that the longer the effective lifetime, the slower the recombination rate of minority carriers. Moreover, conversion efficiency improves by comprising a solar cell element using the semiconductor substrate with a long effective lifetime.

The double-sided light receiving solar cell element in the present invention includes a semiconductor substrate having a front light receiving surface and a back light receiving surface opposite to the front light receiving surface. The semiconductor substrate is not particularly limited, and can be appropriately selected from those usually used according to the purpose. Examples of the semiconductor substrate include those obtained by doping (diffusing) p-type impurities or n-type impurities into silicon, germanium, or the like. Of these, a silicon substrate is preferable. The semiconductor substrate may be a p-type semiconductor substrate or an n-type semiconductor substrate. Among these, from the viewpoint of the passivation effect, it is preferable that the surface on which the passivation layer is formed (that is, at least one of the two light receiving surfaces and the side surface) be a p-type layer. Even if the p-type layer on the semiconductor substrate is a p-type layer derived from the p-type semiconductor substrate, the p-type layer is formed on the n-type semiconductor substrate or the p-type semiconductor substrate as a p-type diffusion layer or a p ⁺ -type diffusion layer. It may be.

  In the semiconductor substrate, the p-type layer and the n-type layer are preferably pn-junctioned. That is, when the semiconductor substrate is a p-type semiconductor substrate, an n-type layer is preferably formed on the front light receiving surface or the back light receiving surface of the semiconductor substrate. When the semiconductor substrate is an n-type semiconductor substrate, a p-type layer is preferably formed on the front light receiving surface or the back light receiving surface of the semiconductor substrate. The method for forming the p-type layer or the n-type layer on the semiconductor substrate is not particularly limited, and can be appropriately selected from commonly used methods.

  The thickness of the semiconductor substrate is not particularly limited and can be appropriately selected according to the purpose. For example, the thickness of the semiconductor substrate can be 50 to 1000 μm, and preferably 75 to 750 μm. Moreover, it is not restrict | limited to the shape and magnitude | size of a semiconductor substrate, For example, it can be set as the square whose one side is 125-156 mm.

  The double-sided light receiving solar cell element of the present invention has a light receiving surface electrode disposed on the front light receiving surface and the back light receiving surface. For example, the light receiving surface electrode has a function of collecting current on the light receiving surface of the semiconductor substrate.

  The material of the light-receiving surface 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 0.1 to 50 μm from the viewpoint of conductivity and homogeneity.

  The light-receiving surface electrode can be manufactured by a commonly used method. For example, it can be manufactured by applying an electrode forming paste such as a silver paste, an aluminum paste, or a copper paste to a desired region of a semiconductor substrate, and performing a heat treatment (firing) as necessary.

The double-sided light receiving solar cell element of the present invention has a passivation layer containing a specific metal oxide on at least one of the front light receiving surface, the back light receiving surface and the side surface of the semiconductor substrate. Furthermore, the passivation layer may contain Al ₂ O ₃ . The passivation layer may be provided on a part or the entire surface of the at least one surface, and is preferably provided in a region other than the electrode. The electrode may be formed so as to overlap with the passivation layer.

  The average thickness of the passivation layer formed on the semiconductor substrate is not particularly limited and can be appropriately selected depending on the purpose. For example, the average thickness of the passivation layer is preferably 5 nm to 50 μm, more preferably 10 nm to 30 μm, and still more preferably 15 nm to 20 μm from the viewpoint of the passivation effect. Here, the average thickness of the passivation layer is calculated as an arithmetic average value by measuring the thickness at five points by an ordinary method using an interference film thickness meter (for example, F20 film thickness measurement system manufactured by Filmetric Co., Ltd.). The

The content of the specific metal oxide contained in the passivation layer is preferably 0.1 to 100% by mass, more preferably 1 to 100% by mass, from the viewpoint of obtaining a sufficient passivation effect. More preferably, it is 10-100 mass%.
The content rate of the specific metal oxide contained in the passivation layer is measured by the following method. The ratio of the inorganic substance is calculated from the thermogravimetric analysis method using atomic absorption spectrometry, inductively coupled plasma emission spectrometry, thermogravimetric analysis, X-ray photoelectric spectroscopy, or the like. Next, the ratio of the compound of the specific metal element in the inorganic substance is calculated by atomic absorption spectrometry, inductively coupled plasma emission spectrometry, etc., and further the specific metal element in the compound by X-ray photoelectric spectroscopy, X-ray absorption spectroscopy, etc. The ratio of the specific metal oxide is calculated.

  The passivation layer may further contain other metal oxides other than the specific metal oxide. Other metal oxides are preferably compounds having a fixed charge, specifically, aluminum oxide, silicon oxide, titanium oxide, gallium oxide, zirconium oxide, boron oxide, indium oxide, phosphorus oxide, zinc oxide, lanthanum oxide. , Praseodymium oxide, neodymium oxide, promethium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, etc. From this viewpoint, it is preferably at least one selected from the group consisting of silicon oxide, titanium oxide, zirconium oxide, neodymium oxide and aluminum oxide, and preferably contains at least aluminum oxide. Preferred.

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

Preferably the density of the passivation layer is 1.0 to 10.0 g / cm ^3, more preferably 2.0~8.0g / cm ^3, is 3.0~7.0g / cm ³ More preferably. When the density of the passivation layer is 1.0 to 10.0 g / cm ³ , a sufficient passivation effect is obtained, and the high passivation effect tends to hardly change over time. The reason is that when the density of the passivation layer is 1.0 g / cm ³ or more, the moisture and impurity gas in the outside world do not easily reach the interface between the semiconductor substrate and the passivation layer, and the passivation effect is easily sustained. It is presumed that the interaction with the semiconductor substrate tends to increase when the concentration is 0.0 g / cm ³ or less. As a method for measuring the density of the passivation layer, a method of measuring and calculating the mass and volume of the passivation layer, an X-ray reflectivity method, and making X-rays incident on the sample surface at a very shallow angle, the incident angle versus the mirror surface direction. A method of determining the film thickness and density of the sample by measuring the X-ray intensity profile reflected on the surface, comparing the profile obtained by the measurement with the simulation result, and optimizing the simulation parameters.

<Composition for forming a passivation layer>
The passivation layer of the double-sided light-receiving solar cell element of the present invention is preferably a heat-treated product of the composition for forming a passivation layer. The composition for forming a passivation layer is not particularly limited as long as it can form a passivation layer containing a specific metal oxide by heat treatment. Even if it contains the specific metal oxide itself, the metal containing the specific metal element A precursor of a specific metal oxide such as alkoxide may be included. Hereinafter, the specific metal oxide and its precursor are also referred to as a specific metal compound.

  The specific metal compound is preferably at least one selected from the group consisting of the specific metal oxide itself and a compound represented by the following general formula (I) (hereinafter also referred to as a compound of formula (I)).

M (OR ¹ ) _m (I)

In general 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 of 1 to 5.

  In the general formula (I), M contains at least one metal element selected from the group consisting of Nb, Ta, V, Y and Hf. From the viewpoint of the passivation effect, the storage stability of the composition for forming a passivation layer, and the workability when preparing the composition for forming a passivation layer, M is preferably Nb, Ta or Y.

In general formula (I), each R ¹ independently represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms, and an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 9 carbon atoms. It is preferable that The alkyl group represented by R ¹ may be linear or branched. Specific examples of the alkyl group represented by R ¹ include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, 2-butyl, t-butyl, pentyl, hexyl, and heptyl groups. Octyl group, 2-ethylhexyl group, 3-ethylhexyl group and the like. Specific examples of the aryl group represented by R ¹ include a phenyl group. The alkyl group and aryl group represented by R ¹ may have a substituent, and examples of the substituent of the alkyl group include a halogen atom, an amino group, a hydroxyl group, a carboxyl group, a sulfone group, and a nitro group. Can be mentioned. Examples of the substituent for the aryl group include a halogen atom, a methyl group, an ethyl group, an isopropyl group, an amino group, a hydroxyl group, a carboxyl group, a sulfone group, and a nitro group.
Among these, R ¹ is preferably an unsubstituted alkyl group having 1 to 8 carbon atoms, and more preferably an unsubstituted alkyl group having 1 to 4 carbon atoms, from the viewpoint of storage stability and a passivation effect.

  In general formula (I), m represents an integer of 0 to 5, preferably an integer of 1 to 5. M is preferably 5 when M is Nb, m is preferably 5 when M is Ta, and m is 3 when M is VO. Preferably, when M is Y, m is preferably 3, and when M is Hf, m is preferably 4.

In the compound represented by the general formula (I), M is preferably Nb, Ta or Y from the viewpoint of the passivation effect, and R ¹ has ¹ to 4 carbon atoms from the viewpoint of storage stability and the passivation effect. It is more preferable that it is an unsubstituted alkyl group, and it is preferable that m is an integer of 1-5 from a viewpoint of storage stability. 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 Nb, Ta, V More preferably, it is at least one selected from the group consisting of Y, H and Hf.

  The compound represented by the general formula (I) may be solid or liquid. From the viewpoint of the storage stability of the composition for forming a passivation layer and the compatibility with the organoaluminum compound represented by the general formula (II) described later, the compound represented by the general formula (I) is: It is preferably a liquid.

  Compounds of the general formula (I) include niobium methoxide, niobium ethoxide, niobium isopropoxide, niobium n-propoxide, niobium n-butoxide, niobium t-butoxide, niobium isobutoxide, tantalum methoxide, tantalum ethoxide, Tantalum isopropoxide, tantalum n-propoxide, tantalum n-butoxide, tantalum t-butoxide, tantalum isobutoxide, yttrium methoxide, yttrium ethoxide, yttrium isopropoxide, yttrium n-propoxide, yttrium n-butoxide, yttrium Examples thereof include t-butoxide, yttrium isobutoxide, etc. Among them, niobium ethoxide, niobium n-propoxide, niobium n-butoxide, tantalum ethoxide, tantalum n-propoxy , Tantalum n- butoxide, yttrium isopropoxide and yttrium n- butoxide.

  As the compound represented by the general formula (I), a prepared product or a commercially available product may be used. Commercially available products include, for example, pentamethoxyniobium, pentaethoxyniobium, penta-i-propoxyniobium, penta-n-propoxyniobium, penta-i-butoxyniobium, penta-n-butoxyniobium, penta 2-butoxy niobium, pentamethoxy tantalum, pentaethoxy tantalum, penta-i-propoxy tantalum, penta-n-propoxy tantalum, penta-i-butoxy tantalum, penta-n-butoxy tantalum, penta-2-butoxy tantalum, penta T-butoxy tantalum, vanadium (V) trimethoxide oxide, vanadium (V) triethoxide oxide, vanadium (V) tri-i-propoxide oxide, vanadium (V) tri-n-propoxide oxide, vanadium ( V) Tri-i-B Xoxide, vanadium (V) tri-n-butoxide oxide, vanadium (V) tri-2-butoxide oxide, vanadium (V) tri-t-butoxide oxide, tri-i-propoxy yttrium, tri-n-butoxy yttrium, tetra Methoxyhafnium, tetraethoxyhafnium, tetra-i-propoxyhafnium, tetra-t-butoxyhafnium; pentaethoxyniobium, pentaethoxytantalum, pentabutoxytantalum, yttrium-n-butoxide, hafnium-t-butoxide from Hokuko Chemical Co., Ltd. Nichia Corporation's vanadium oxytriethoxide, vanadium oxytri-normal propoxide, vanadium oxytri-normal butoxide, vanadium oxytriisobutoxide, vana It can be mentioned um oxy tri secondary butoxide and the like.

  When preparing the compound of the general formula (I), the preparation method is as follows. The halide of the metal element (M) and the alcohol contained in the compound represented by the general formula (I) are present in the presence of an inert organic solvent. A known production method such as a method of reacting and adding ammonia or an amine compound to further extract halogen (see, for example, JP-A-63-227593 and JP-A-3-291247) can be used. .

  The content rate of the compound represented by general formula (I) contained in the said composition for formation of a passivation layer can be suitably selected as needed. The content rate of the compound represented by general formula (I) can be 0.1-80 mass% in the composition for formation of a passivation layer from a viewpoint of storage stability and a passivation effect, It is preferable that it is -70 mass%, It is more preferable that it is 1-60 mass%, It is still more preferable that it is 1-50 mass%.

  When the composition for forming a passivation layer contains a compound represented by the general formula (I), a chelating reagent (chelating agent) may be added. As a chelating reagent, dicarboxylic acid compounds such as EDTA (ethylenediaminetetraacetic acid), bipyridine, heme, naphthyridine, benzimidazolylmethylamine, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, tartaric acid, maleic acid, phthalic acid, etc. , Β-diketone compounds, β-ketoester compounds, and malonic acid diester compounds. From the viewpoint of chemical stability, β-diketone compounds and β-ketoester compounds are preferred.

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

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

  Specific examples of the malonic acid diester compound include dimethyl malonate, diethyl malonate, dipropyl malonate, diisopropyl malonate, dibutyl malonate, di-t-butyl malonate, dihexyl malonate, t-butylethyl malonate, and methylmalon. Examples include diethyl acid, diethyl ethylmalonate, diethyl isopropylmalonate, diethyl butylmalonate, diethyl 2-butylmalonate, diethyl isobutylmalonate, diethyl 1-methylbutylmalonate, and the like.

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

  The compound represented by the general formula (I) may be used in a state of hydrolysis and dehydration condensation polymerization. For hydrolysis and dehydration condensation polymerization, the reaction can proceed in the presence of water and a catalyst. After hydrolysis and dehydration condensation polymerization, water and catalyst may be distilled off. Catalysts include 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, salicylic acid, benzoic acid, phthalic acid, oxalic acid And organic acids such as lactic acid and succinic acid. Moreover, you may add bases, such as ammonia and an amine, as a catalyst.

  The composition for forming a passivation layer may contain a precursor of a specific metal oxide other than the compound represented by the general formula (I). The precursor of a specific metal oxide will not be restrict | limited especially if it becomes a specific metal oxide by heat processing. Specifically, niobic acid, niobium chloride, niobium monoxide, niobium carbide, niobium hydroxide, tantalum acid, tantalum chloride, tantalum pentabromide, vanadium oxychloride, vanadium trioxide, oxobis (2,4-pentanedio Nato) vanadium, yttrium chloride, yttrium nitrate, yttrium oxalate, yttrium stearate, yttrium carbonate, yttrium naphthenate, yttrium propionate, yttrium nitrate, yttrium octylate, hafnium chloride, tetrakis (2,4-pentandionato) hafnium Etc. can be illustrated.

  The composition for forming a passivation layer may further contain a metal oxide other than the specific metal compound or a precursor thereof. Examples of such metal oxides or precursors thereof include aluminum oxide, silicon oxide, titanium oxide, gallium oxide, zirconium oxide, boron oxide, indium oxide, phosphorus oxide, zinc oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, and oxidation. Mention may be made of promethium, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, and precursors thereof. From the viewpoint of the stability of the passivation effect, aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, neodymium oxide or a precursor thereof is preferable, and from the viewpoint of a high passivation effect, aluminum oxide or a precursor thereof is more preferable. .

  It is preferable that the said composition for passivation layer formation contains 1 or more types selected from the group which consists of aluminum oxide and its precursor further in addition to a specific metal compound. As a precursor of aluminum oxide, a compound represented by the following general formula (II) (hereinafter also referred to as an organoaluminum compound) is preferable.

The organoaluminum compound is a compound called aluminum alkoxide, aluminum chelate or the like. As described in Nippon Seramikkusu Kyokai Gakujitsu Ronbunshi, 97 (1989) 369-399, the organoaluminum compound becomes aluminum oxide (Al ₂ O ₃ ) by heat treatment.

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

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

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

In general formula (II), R < ³ >, R < ⁴ > and R < ⁵ > represent a hydrogen atom or a C1-C8 alkyl group each independently. 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 groups represented by R ³ , R ⁴ and R ⁵ are each independently an alkyl group having 1 to 8 carbon atoms, and preferably an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group represented by R ³ , R ⁴ and R ⁵ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a 2-butyl group, a t-butyl group, and a hexyl group. Octyl group, 2-ethylhexyl group and the like. Among these, from the viewpoint of storage stability and a passivation effect, R ³ and R ⁴ in the general formula (II) are preferably each independently a hydrogen atom or an unsubstituted alkyl group having 1 to 8 carbon atoms. Or it is more preferable that it is a C1-C4 unsubstituted alkyl group.
R ⁵ in the general formula (II) is preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 8 carbon atoms from the viewpoint of storage stability and a passivation effect, and is a hydrogen atom or 1 to 4 carbon atoms. It is more preferably an unsubstituted alkyl group.

In the organoaluminum compound represented by the general formula (II), n is an integer of 1 to 3 from the viewpoint of storage stability, and R ⁵ is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. A certain compound is preferable.

The organoaluminum compound represented by the general formula (II) is a compound in which n is 0 and R ² is each independently an alkyl group having 1 to 4 carbon atoms from the viewpoint of storage stability and a passivation effect, n is 1 to 3, R ² is each 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 It is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ⁵ is at least one selected from the group consisting of a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

Furthermore, in the organoaluminum compound represented by the general formula (II), n is 0, R ² is each independently an unsubstituted alkyl group having 1 to 4 carbon atoms, and n is 1 to 3 R ² is each independently an unsubstituted alkyl group having 1 to 4 carbon atoms, at least one of X ² and X ³ is an oxygen atom, and R ³ or R ⁴ bonded to the oxygen atom is A group consisting of a compound having an alkyl group having 1 to 4 carbon atoms and when X ² or X ³ is a methylene group, R ³ or R ⁴ bonded to the methylene group is a hydrogen atom, and R ⁵ is a hydrogen atom; More preferably, it is at least one selected from more.

  Specific examples of the aluminum trialkoxide, which is an organoaluminum compound represented by the general formula (II) and n is 0, include trimethoxyaluminum, triethoxyaluminum, triisopropoxyaluminum, tri-2-butoxyaluminum, mono-2-butoxy. -Diisopropoxyaluminum, tri-t-butoxyaluminum, tri-n-butoxyaluminum, etc. can be mentioned.

  Specific examples of the organoaluminum compound represented by the general formula (II) where n is 1 to 3 include aluminum ethyl acetoacetate diisopropylate and tris (ethyl acetoacetate) aluminum.

  As the organoaluminum compound represented by the general formula (II) and n of 1 to 3, a prepared product or a commercially available product may be used. Examples of commercially available products include Kawaken Fine Chemical Co., Ltd. trade names, ALCH, ALCH-50F, ALCH-75, ALCH-TR, ALCH-TR-20, and the like.

  The organoaluminum compound preferably has n of 1 to 3, that is, an aluminum chelate structure in addition to the aluminum alkoxide structure. When n is 0, that is, when it exists in the composition for forming a passivation layer in the state of an aluminum alkoxide structure, it is preferable to add a chelating reagent (chelating agent) to the composition for forming a passivation layer. Examples of chelating reagents include those described above.

  When the organoaluminum compound has a chelate structure, the presence of the chelate structure can be confirmed by a commonly used analysis method. For example, it can be confirmed using an infrared spectrum, a nuclear magnetic resonance spectrum, a melting point, or the like.

  By using an aluminum alkoxide and a chelating reagent in combination or using a chelated organoaluminum compound, the thermal and chemical stability of the organoaluminum compound is improved, and the transition to aluminum oxide during heat treatment is suppressed. it is conceivable that. As a result, it is considered that the transition to thermodynamically stable crystalline aluminum oxide is suppressed, and amorphous aluminum oxide is easily formed.

  In addition, the state of the metal oxide in the formed passivation layer can be confirmed by measuring an X-ray diffraction spectrum (XRD, X-ray diffraction). For example, it can be confirmed that the XRD has an amorphous structure by not showing a specific reflection pattern. When the composition for forming a passivation layer contains an organoaluminum compound, it is preferable that the aluminum oxide in the passivation layer obtained by heat-treating it has an amorphous structure. When the aluminum oxide is in an amorphous state, aluminum deficiency or oxygen deficiency is likely to occur, fixed charges are likely to be generated in the passivation layer, and a large passivation effect is likely to be obtained.

  The organoaluminum compound represented by the general formula (II) and n is 1 to 3 can be prepared by mixing the aluminum trialkoxide and a chelating reagent. Examples of the chelating reagent include compounds having a specific structure having two carbonyl groups. Specifically, when the aluminum trialkoxide is mixed with a compound having a specific structure having two carbonyl groups, at least a part of the alkoxide group of the aluminum trialkoxide is substituted with a compound having a specific structure, thereby forming an aluminum chelate structure. Form. At this time, if necessary, a solvent may be present, or heat treatment or addition of a catalyst may be performed. By replacing at least a part of the aluminum alkoxide structure with an aluminum chelate structure, the stability of the organoaluminum compound to hydrolysis and polymerization reaction is improved, and the storage stability of the composition for forming a passivation layer containing this is further improved. To do.

  The compound having a specific structure having two carbonyl groups may be at least one selected from the group consisting of a β-diketone compound, a β-ketoester compound, and a malonic acid diester from the viewpoint of reactivity and storage stability. preferable. Specific examples of the β-diketone compound, β-ketoester compound and malonic acid diester include the compounds described above as chelating reagents.

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

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

  The organoaluminum compound may be liquid or solid and is not particularly limited. From the viewpoint of the passivation effect and storage stability, the uniformity of the passivation layer formed can be achieved by using an organoaluminum compound that is stable at room temperature (about 10 ° C. to 40 ° C.) and has good solubility or dispersibility. It can improve further and can acquire the desired passivation effect stably.

When the composition for forming a passivation layer contains one or more aluminum compounds selected from the group consisting of Al ₂ O ₃ and the organoaluminum compound, the total content of the aluminum compounds in the composition for forming a passivation layer The rate is preferably 0.1 to 80% by mass, and more preferably 10 to 70% by mass. From the viewpoint of the high passivation effect, the total ratio of the aluminum compound in the total amount of the specific metal compound and the aluminum compound is preferably 0.1% by mass or more and 99.9% by mass or less. 5 mass% or more and 99 mass% or less are more preferable, and 1 mass% or more and 95 mass% or less are still more preferable.

When the composition for forming a passivation layer contains the aluminum compound, the composition of the specific metal oxide in the passivation layer obtained by heat-treating the composition for forming a passivation layer includes Nb ₂ O ₅ —Al ₂ O ₃ , Binary complex oxides such as Al ₂ O 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 ; 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 Examples thereof include ternary complex oxides such as ₂ O ₅ .

From the viewpoint of the high passivation effect and the temporal stability of the passivation effect, the composition for forming a passivation layer is selected from the group consisting of Nb ₂ O ₅ and a compound in which M is Nb in the general formula (I). It is preferable to contain at least one niobium compound. The total content of the niobium compound of the passivation layer forming composition is preferably a 0.1 to 99.9 wt% calculated as _Nb 2 _{O 5,} more to be 1 to 99 wt% Preferably, it is 5-90 mass%. Identification in a passivation layer obtained by heat-treating a composition for forming a passivation layer containing Nb ₂ O ₅ and at least one niobium compound selected from the group consisting of compounds in which M is Nb in the general formula (I) Examples of the composition of the metal oxide include Nb ₂ O ₅ —Al ₂ O ₃ , Nb ₂ O ₅ —Ta ₂ O ₅ , Nb ₂ O ₅ —Y ₂ O ₃ , Nb ₂ O ₅ —V ₂ O ₅ , Binary complex oxides such as Nb ₂ O ₅ —HfO ₂ ; 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 such as _{-Al 2 O 3 -V 2 O 5} , Nb 2 O 5 -HfO 2 -Ta 2 O ternary composite oxide such as ₅ can be mentioned.

  A composition for forming a passivation layer containing a specific metal compound is applied to a semiconductor substrate to form a composition layer having a desired shape, and the composition layer is heat-treated to obtain a desired passivation layer having an excellent passivation effect. It can be formed into a shape.

  The inventors consider the reason why a passivation layer having an excellent passivation effect can be formed by heat-treating the composition for forming a passivation layer as follows. It is considered that when the composition for forming a passivation layer containing a specific metal compound is heat-treated, defects such as metal atoms and oxygen atoms are generated and a large fixed charge is generated in the vicinity of the interface with the semiconductor substrate. This large fixed charge generates an electric field in the vicinity of the interface of the semiconductor substrate, so that the concentration of minority carriers can be reduced. As a result, the carrier recombination rate at the interface is suppressed, so that it has an excellent passivation effect. It is believed that a passivation layer can be formed. Furthermore, it is thought that the composition for forming a passivation layer is excellent in storage stability over time because the occurrence of problems such as gelation is suppressed.

(Liquid medium)
The composition for forming a passivation layer preferably contains a liquid medium. When the composition for forming a passivation layer contains a liquid medium, the viscosity can be adjusted more easily, the applicability can be further improved, and a more uniform passivation layer can be formed. The liquid medium is not particularly limited as long as it can dissolve or disperse the specific metal compound, and can be appropriately selected as necessary. The liquid medium preferably contains at least one selected from a hydrophobic organic solvent, an aprotic organic solvent, a terpene solvent, an ester solvent, an ether solvent, and an alcohol solvent.

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

  The liquid medium is a group consisting of a terpene solvent, an ester solvent, and an alcohol solvent from the viewpoint of impartability to a semiconductor substrate and pattern formability (inhibition of pattern enlargement during application of a passivation layer forming composition and drying). It is preferable to include at least one selected from the above, and it is more preferable to include at least one terpene solvent.

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

(resin)
It is preferable that the composition for forming a passivation layer further contains at least one resin. By including the resin, the shape stability of the composition layer formed by applying the passivation layer-forming composition on the semiconductor substrate is further improved, and the passivation layer is desired in the region where the composition layer is formed. It becomes easier to selectively form with this shape.

  The type of the resin is not particularly limited, and is preferably a resin whose viscosity can be adjusted within a range where a good pattern can be formed when the composition for forming a passivation layer is applied onto a semiconductor substrate. Specific examples of the resin include cellulose derivatives such as polyvinyl alcohol, polyacrylamide, polyvinylamide, polyvinylpyrrolidone, polyethylene oxide, polysulfone, polyacrylamide alkylsulfone, cellulose ether such as cellulose, carboxymethylcellulose, hydroxyethylcellulose, ethylcellulose, gelatin, and gelatin. Derivatives, starch and starch derivatives, sodium alginate and sodium alginate derivatives, xanthan and xanthan derivatives, guar gum and guar gum derivatives, scleroglucan and scleroglucan derivatives, tragacanth and tragacanth derivatives, dextrin and dextrin derivatives, (meth) acrylic acid resins, (Meth) acrylic ester resins (eg, alkyl (meta Acrylate resins, dimethylaminoethyl (meth) acrylate resin, etc.), butadiene resins, styrene resins, siloxane resins, and the like of these copolymers. These resins can be used alone or in combination of two or more.

Among these resins, from the viewpoint of storage stability and pattern formation, it is preferable to use a neutral resin having no acidic or basic functional group, and the viscosity and thixotrope can be easily used even when the content is small. From the viewpoint of adjusting the properties, it is more preferable to use a cellulose derivative.
The molecular weight of the resin is not particularly limited, and is preferably adjusted appropriately in view of the desired viscosity as the composition for forming a passivation layer. The weight average molecular weight of the resin is preferably 1,000 to 10,000,000, more preferably 3,000 to 5,000,000, from the viewpoints of storage stability and pattern formation. In addition, the weight average molecular weight of resin is calculated | required by converting using the analytical curve of a standard polystyrene from molecular weight distribution measured using GPC (gel permeation chromatography). The calibration curve is approximated by a cubic equation using a standard polystyrene 5 sample set (PStQuick MP-H, PStQuick B [trade name, manufactured by Tosoh Corporation]). The measurement conditions for GPC are shown below.

Device: (Pump: L-2130 [Hitachi High-Technologies Corporation])
(Detector: L-2490 RI [Hitachi High-Technologies Corporation])
(Column oven: L-2350 [Hitachi High-Technologies Corporation])
Column: Gelpack GL-R440 + Gelpack GL-R450 + Gelpack GL-R400M (3 in total) (Hitachi Chemical Co., Ltd., trade name)
Column size: 10.7 mm (inner diameter) x 300 mm
Eluent: Tetrahydrofuran Sample concentration: 10 mg / 2 mL
Injection volume: 200 μL
Flow rate: 2.05 mL / min Measurement 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 can be appropriately selected as necessary. For example, it is preferable that it is 0.1-30 mass% in the gross mass of the composition for passivation layer formation. From the viewpoint of expressing thixotropy that facilitates pattern formation, the content is more preferably 1 to 25% by mass, still more preferably 1.5 to 20% by mass, Even more preferably, it is 10 mass%.

  When the composition for forming a passivation layer contains a resin, the content ratio of the organoaluminum compound and the resin in the composition for forming a passivation layer can be appropriately selected as necessary. Above all, from the viewpoint of pattern formability and storage stability, the ratio of the resin when the total amount of one or more selected from the group consisting of the specific metal compound and the aluminum oxide and precursor thereof contained as necessary is 1. Is preferably 0.001 to 1000, more preferably 0.01 to 100, and still more preferably 0.1 to 1.

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

  Examples of acidic compounds include Bronsted acid and Lewis acid. Specific examples include inorganic acids such as hydrochloric acid and nitric acid, and organic acids such as acetic acid. Examples of basic compounds include Bronsted bases and Lewis bases. Specific examples include inorganic bases such as alkali metal hydroxides and alkaline earth metal hydroxides; organic bases such as trialkylamines and pyridines.

  The composition for forming a passivation layer contains various additives such as a thickener, a wetting agent, a surfactant, an inorganic powder, a resin containing a silicon atom, a thixotropic agent, as other components, as necessary. Also good.

  Examples of the inorganic powder include silica (silicon oxide), clay, silicon carbide, silicon nitride, montmorillonite, bentonite, and carbon black. Among these, it is preferable to use a filler containing silica as a component. Here, clay refers to a layered clay mineral, and specific examples include kaolinite, imogolite, montmorillonite, smectite, sericite, illite, talc, stevensite, and zeolite. When the composition for forming a passivation layer contains an inorganic powder, the impartability of the composition for forming a passivation layer tends to be improved.

  Examples of the surfactant include a nonionic surfactant, a cationic surfactant, and an anionic surfactant. Among these, nonionic surfactants or cationic surfactants are preferred because impurities such as heavy metals are not brought into the semiconductor device. Examples of nonionic surfactants include silicone surfactants, fluorine surfactants, hydrocarbon surfactants, and the like. When the composition for forming a passivation layer contains a surfactant, the thickness and composition uniformity of the composition layer formed from the composition for forming a passivation layer tend to be improved.

  Examples of the resin containing silicon atoms include lysine-modified silicones at both ends, polyamide-silicone alternating copolymers, side-chain alkyl-modified silicones, side-chain polyether-modified silicones, terminal alkyl-modified silicones, silicone-modified pullulans, and silicone-modified acrylic resins. It can be illustrated. When the composition for forming a passivation layer contains a resin containing silicon, the thickness and composition uniformity of the composition layer formed from the composition for forming a passivation layer tend to be improved.

  Examples of thixotropic agents include polyether compounds, fatty acid amides, fumed silica, hydrogenated castor oil, urea urethane amide, polyvinyl pyrrolidone, and oil-based gelling agents. When the composition for forming a passivation layer contains a thixotropic agent, the pattern formability when applying the composition for forming a passivation layer tends to be improved. Examples of the polyether compound include polyethylene glycol, polypropylene glycol, poly (ethylene-propylene) glycol copolymer, and the like.

The viscosity of the composition for forming a passivation layer is not particularly limited, and can be appropriately selected depending on a method for applying the composition to a semiconductor substrate. For example, the viscosity of the composition for forming a passivation layer can be 0.01 to 10,000 Pa · s. Among these, from the viewpoint of pattern formability, the viscosity of the composition for forming a passivation layer is preferably 0.1 to 1000 Pa · s. The viscosity is a value measured at 25 ° C. and a shear rate of 1.0 s ⁻¹ using a rotary shear viscometer.

It is preferable that the composition for forming a passivation layer has thixotropy. In particular, thixotropic passivation layer forming composition may contain a resin, from the viewpoint of pattern formability, which is calculated by dividing the shear viscosity η1 at a shear rate of 1.0 s ^-1 at shear viscosity η2 at a shear rate of 10s ^-1 The ratio (η1 / η2) is preferably 1.05 to 100, more preferably 1.1 to 50. The shear viscosity is measured at a temperature of 25 ° C. using a rotary shear viscometer equipped with a cone plate (diameter 50 mm, cone angle 1 °).

There is no restriction | limiting in particular in the manufacturing method of the composition for formation of a passivation layer. For example, a specific metal compound and a liquid medium or the like contained as necessary can be mixed and produced by a commonly used method. Moreover, you may manufacture by mixing the liquid medium and resin which dissolved resin, and a specific metal compound.
Furthermore, the specific metal compound may be prepared by mixing the compound of general formula (I) and a compound capable of forming a chelate with the metal element contained in the compound of general formula (I). At that time, a solvent may be appropriately used or heat treatment may be performed. A composition for forming a passivation layer may be produced using the specific metal compound thus prepared.
The components contained in the composition for forming a passivation layer, and the content of each component are thermal analysis such as differential thermal-thermogravimetric simultaneous measurement (TG / DTA), nuclear magnetic resonance (NMR), infrared spectroscopy. It can be confirmed by spectral analysis such as (IR), chromatographic analysis such as high performance liquid chromatography (HPLC), gel permeation chromatography (GPC) and the like.

<Method for producing double-sided light receiving solar cell element>
The method for manufacturing a double-sided light-receiving solar cell element according to the present invention includes a step of forming a light-receiving surface electrode on a front light-receiving surface and a back light-receiving surface of a semiconductor substrate; Nb ₂ O ₅ , Ta ₂ O ₅ , V ₂ O ₅ , Y ₂ O ₃ , HfO ₂ and one or more compounds selected from the group consisting of the compounds represented by the general formula (I) A step of applying a passivation layer forming composition to form a composition layer, and a step of heat-treating the composition layer to form a passivation layer. The method for producing a double-sided light-receiving solar cell element of the present invention may further include other steps as necessary.

  According to the above method, a passivation layer having an excellent passivation effect can be formed on the semiconductor substrate. In addition, the passivation layer can be formed with high productivity by a simple method that does not require a vapor deposition apparatus or the like. Therefore, according to the said method, the solar cell element excellent in conversion efficiency can be manufactured by a simple method.

  As a method for forming the light-receiving surface electrode on the semiconductor substrate, a commonly used method can be employed. For example, it can be formed by applying an electrode forming paste such as a silver paste or an aluminum paste to a desired region of a semiconductor substrate and performing a heat treatment (firing) as necessary.

  The step of forming the light-receiving surface electrode may be before the step of forming the composition layer by applying the composition for forming a passivation layer to at least one of the light-receiving surface, the back light-receiving surface, and the side surface of the semiconductor substrate. Or later. Further, the heat treatment (firing) for forming the electrode and the heat treatment (firing) for forming the passivation layer from the composition layer may be performed collectively or separately as independent steps.

  Moreover, it is preferable to further have the process of providing aqueous alkali solution to a semiconductor substrate before the process of forming the said composition layer. That is, it is preferable to wash the surface of the semiconductor substrate with an alkaline aqueous solution before applying the passivation layer forming composition onto the semiconductor substrate. By washing with an alkaline aqueous solution, organic substances, particles, and the like present on the surface of the semiconductor substrate can be removed, and the passivation effect is further improved.

  As a method for cleaning with an alkaline aqueous solution, generally known RCA cleaning and the like can be exemplified. For example, an organic substance and particles can be removed and washed by immersing the semiconductor substrate in a mixed solution of ammonia water and hydrogen peroxide solution and treating at 60 to 80 ° C. The washing time is preferably 10 seconds to 10 minutes, and more preferably 30 seconds to 5 minutes.

  There is no particular limitation on the method for forming the composition layer on at least one of the light receiving surface, the back light receiving surface, and the side surface of the semiconductor substrate by using the passivation layer forming composition. For example, the method of providing the said composition for passivation layer formation on a semiconductor substrate using a well-known coating method etc. can be mentioned. Specific examples include a printing method such as an immersion method and a screen printing method, a spin coating method, a brush coating method, a spray method, a doctor blade method, a roll coater method, and an ink jet method. Among these, from the viewpoint of pattern formation, a spin coating method, a screen printing method, and an ink jet method are preferable, and a screen printing method is more preferable.

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

A passivation layer is formed on a semiconductor substrate by heat-treating (baking) the composition layer formed by the composition for forming a passivation layer to form a heat-treated layer (baked material layer) derived from the composition layer. be able to.
There are no particular restrictions on the heat treatment (firing) conditions of the composition layer. When the composition for forming a passivation layer contains a specific metal compound and other optional metal compounds (such as organoaluminum compounds), the specific metal oxide and other metal oxides that are heat-treated products (fired products) If it can be converted into (aluminum oxide (Al ₂ O ₃ ) or the like), the heat treatment (firing) conditions of the composition layer are not particularly limited.

  Among them, the heat treatment (firing) conditions that can form an amorphous specific metal oxide having no crystal structure are preferable. When the passivation layer is composed of an amorphous specific metal oxide, the passivation layer can effectively have a negative charge, and a more excellent passivation effect can be obtained. Specifically, the heat treatment (firing) temperature is preferably 400 ° C. or higher, more preferably 400 to 900 ° C., and still more preferably 600 to 800 ° C. The heat treatment (firing) time can be appropriately selected according to the heat treatment (firing) temperature and the like. For example, it can be 0.1 to 10 hours, and preferably 0.2 to 5 hours.

  Moreover, you may further have the process of drying a composition layer before the process of heat-processing (baking) a composition layer and forming a passivation layer. By having the process of drying the composition layer, a passivation layer having a more uniform passivation effect can be formed.

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

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view schematically illustrating an example of a method for producing a double-sided light receiving solar cell element capable of receiving light on both sides having a passivation layer for a semiconductor substrate according to the present embodiment. However, this process diagram does not limit the usage method of the present invention.

In FIG. 1A, an alkaline solution is applied to crystalline silicon as the n-type semiconductor substrate 10 to remove the damaged layer, and then a texture structure is obtained by an etching process or the like.
Specifically, for example, a damaged layer on the silicon surface generated when slicing from an ingot is removed with 20% by mass caustic soda. Next, a texture structure is formed on both sides by alkali etching using an aqueous caustic soda solution of about 5% by mass (the description of the texture structure is omitted in the figure). In the solar battery cell, by forming a texture structure on the light receiving surface (both sides) side, a light confinement effect is promoted, and high efficiency is achieved.

In FIG. 1B, a p ⁺ -type diffusion layer (1) is formed on the front light-receiving surface of the n-type semiconductor substrate 10 using a p-type diffusion composition capable of forming a p + -type diffusion layer by thermal diffusion treatment. Form. In addition, an n ⁺ -type diffusion layer (2) is formed on the back light-receiving surface using an n-type diffusion composition capable of forming an n ⁺ -type diffusion layer by thermal diffusion treatment. Here, the p-type diffusion layer forming composition can be configured to include, for example, an acceptor element-containing material and a glass component. Here, the n ⁺ -type diffusion layer refers to a diffusion layer having a lower resistance than the n layer. In FIG. 1, the p ⁺ type diffusion layer is formed and then the n ⁺ type diffusion layer is formed. However, the order may be reversed, but it is preferable to form the p ⁺ type diffusion layer first. In general, the carrier lifetime decreases when forming the p ⁺ -type diffusion layer, but the carrier lifetime is improved by the step of forming the n ⁺ -type diffusion layer, for example, ring gettering using a phosphorus compound.

Through the above steps, n ⁺ -type diffusion layer on one surface of the light-receiving surface of the semiconductor substrate, a semiconductor substrate p ⁺ -type diffusion layer is formed is obtained on the other side. In the subsequent steps, a passivation layer and an electrode are formed on the diffusion layer to produce a double-sided light receiving solar cell element.

In FIG. 1C, passivation films (3) and (4) are formed on the front light receiving surface and the back light receiving surface of the semiconductor substrate 10. The passivation layers (3) and (4) are passivation films formed by applying the composition for forming a passivation layer according to the present invention by a screen printing method, an ink jet method, a spin coating method, and the like, followed by heat treatment (firing). Preferably there is. Thereby, it is possible to obtain a solar cell element having excellent conversion efficiency and suppressing a decrease in conversion efficiency over time.
The passivation layer (3) provided on the front light-receiving surface is formed by applying the passivation layer forming composition according to the present invention by a screen printing method, an inkjet method, a spin coating method, or the like, and heat-treating (firing) the passivation layer (3). It is preferable to form. On the other hand, the passivation layer (4) provided on the back light-receiving surface is preferably a SiN layer, SiO ₂ layer, amorphous-Si, or Al ₂ O ₃ as a main component, and uses a SiN layer or a SiO ₂ layer. It is preferable. In the case of using the SiO ₂ layer is preferably formed by thermal oxidation.
In addition, the passivation layer may have a two-layer structure on both the front light receiving surface and the back light receiving surface, and after forming the passivation layers (3) and (4) (hereinafter also referred to as “first passivation layer”), further. A passivation layer (5) (hereinafter also referred to as “second passivation layer”) may be formed. By using a two-layer structure, reflection of light can be suppressed. Examples of the second passivation layer include a SiN layer, a ZnS layer, and an MgF layer. The SiN layer is preferable from the viewpoint of suppressing the light reflectance and expecting a high passivation effect. The passivation layer may be three or more layers. The thickness of the entire passivation layer is not particularly limited, but is preferably 5 nm to 50 μm, more preferably 10 nm to 30 μm, more preferably 10 to 300 nm, and more preferably 30 to 150 nm. preferable.

Next, FIG. 1E illustrates a process of forming an electrode. 1E and 1F, an n-electrode (7) is formed on the n ⁺ -type diffusion layer (2), and a p-electrode (6) is formed on the p + -type diffusion layer (1). As a method for forming the electrode, a method for forming the electrode by applying a composition for forming an electrode including glass frit to a portion where the electrode on the passivation layer is to be formed and performing a fire-through, or a method for forming the electrode on the passivation layer where the electrode is to be formed. Examples of the method include forming an opening, supplying an electrode forming composition, and performing heat treatment (firing). If the former method is used, the step of opening the passivation films (3) and (4) can be omitted. An electrode-forming composition containing glass frit is applied onto the passivation films (3) and (4), and baked for several seconds to several minutes in the range of 600 to 900 ° C., the glass frit becomes the passivation films (3) and (4). The metal particles (for example, silver particles) in the composition form a contact portion with the semiconductor substrate 10 and solidify. Thereby, the formed n electrode (7), p electrode (6) and the semiconductor substrate 10 are electrically connected. FIGS. 1E and 1F illustrate the former method. When the latter method is used, it is necessary to form openings for forming electrodes in the passivation films (3) and (4) and expose the p ⁺ type diffusion layer and the n ⁺ type diffusion layer. In this case, an etching solution (a solution containing hydrofluoric acid, ammonium fluoride, phosphoric acid, or the like) is applied to a portion to be opened by an inkjet method or the like, and heat treatment is performed. By supplying the electrode-forming composition to the formed opening and performing heat treatment (firing), the formed n-electrode (7), p-electrode (6) and the semiconductor substrate 10 are electrically connected.
In addition, the material and formation method of n electrode (7) and p electrode (6) are not specifically limited. An electrode forming composition containing a metal such as aluminum, silver, or copper may be applied and dried to form an electrode. Further, the n electrode and the p electrode may be made of the same material.
The electrode is fired to produce a solar cell.

  In FIG. 1, the passivation film (4) is formed and then the passivation film (3) is formed. However, the order may be reversed, but the passivation film (4) is preferably formed first.

Further, FIG. 1C shows a method of forming a passivation layer only on both light receiving surface portions, but the side surface of the semiconductor substrate 10 is formed by applying the passivation layer forming composition to the side surface of the semiconductor substrate 10 and drying it. A passivation layer may be further formed on (edge) (not shown). Thereby, the solar cell element excellent in power generation efficiency can be manufactured.
Furthermore, the passivation layer may be formed by applying the composition for forming a passivation layer of the present invention only on the side surface without forming the passivation layer on the front light receiving surface and the back light receiving surface, and performing heat treatment (firing). When the composition for forming a passivation layer of the present invention is used in a place where there are many crystal defects such as side surfaces, the effect is particularly great.

  Alternatively, an electrode that does not need to be heat-treated (fired) at a high temperature may be formed on the entire surface.

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

<Double-sided solar cell module>
The double-sided light-receiving solar cell module includes at least one of the double-sided light-receiving solar cell elements, and is configured by arranging a wiring material such as a tab wire on the electrode of the double-sided light-receiving solar cell element. If necessary, the double-sided light receiving solar cell may be configured by connecting a plurality of double-sided light receiving solar cell elements via a wiring material and further sealing with a sealing material. The wiring material and the sealing material are not particularly limited, and can be appropriately selected from those usually used in the industry. There is no restriction | limiting in the magnitude | size of the said solar cell module. It is preferable that the 0.5~3m ^2.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “%” is based on mass.

<Example 1> (Preparation of a composition for forming a passivation layer)
Al ₂ O ₃ thin film coating material (manufactured by Kojundo Chemical Laboratory, “SYM-Al04”, Al ₂ O ₃ : 2 mass%, xylene: 87 mass%, 2-propanol: 5 mass%, stabilizer: 6 mass%), 1.0 g of Nb ₂ O ₅ thin film coating material (manufactured by Kojundo Chemical Laboratory Co., Ltd., “Nb-05”, Nb ₂ O ₅ : 5 mass%, n-butyl acetate: 56 mass%, 1.0 g of a stabilizer: 16.5% by mass and a viscosity modifier: 22.5% by mass) were mixed to prepare a composition 1 for forming a passivation layer.

(Formation of passivation layer)
A single crystal p-type silicon substrate (manufactured by SUMCO Corporation, 50 mm square, thickness: 625 μm) having a mirror-shaped surface was used as the semiconductor substrate. The silicon substrate was cleaned by immersing it at 70 ° C. for 5 minutes using an RCA cleaning solution (manufactured by Kanto Chemical Co., Ltd., “Frontier Cleaner-A01”).
Thereafter, 4000 rpm (rotation / min ⁻¹ ) was applied to the entire surface of one surface of the silicon substrate pretreated with the passivation layer forming composition 1 obtained above using a spin coater (“MS-100” manufactured by Mikasa Corporation). ) For 30 seconds. Then, it dried at 150 ° C. for 3 minutes. Subsequently, after heat-treating (baking) in the air at 700 ° C. for 10 minutes, it was allowed to cool at room temperature (25 ° C.) to produce an evaluation substrate.

(Measurement of effective lifetime)
The effective lifetime (μs) of the region where the passivation layer of the evaluation substrate obtained above was formed was measured at room temperature (25 ° C.) using a lifetime measurement device (“WT-2000PVN”, manufactured by Nippon Semi-Lab Co., Ltd.). ) By the reflected microwave photoconductive decay method. The effective lifetime was 480 μs.

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

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

(Production of double-sided light-receiving solar cell element)
A p ⁺ -type diffusion layer was formed on the front light-receiving surface using boronic acid on a 156 mm square n-type silicon substrate that had been subjected to double-sided texture treatment, and an n ⁺ -type diffusion layer was formed on the back light-receiving surface using phosphorus oxychloride. On the back light-receiving surface side, annealing treatment was performed at 600 ° C. for 1 hour to form a diffusion layer. Next, on the front light-receiving surface side, the composition 1 for forming a passivation layer is formed by a solid pattern by inkjet (manufactured by Microjet Co., Ltd., inkjet device “MJP-1500V”, head: IJH-80, nozzle size: 50 μm × 70 μm). The composition for forming a semiconductor substrate passivation layer 1 was applied so that the film thickness after drying was 5 μm. Then, it dried at 150 ° C. for 3 minutes. Next, after heat treatment (baking) at 550 ° C. for 1 hour, the mixture was allowed to cool to room temperature (25 ° C.). Thereafter, a SiNx film was formed on both light-receiving surfaces using plasma CVD (SiNx film thickness: 80 nm).

Thereafter, a silver electrode-forming composition (manufactured by DuPont, “PV159A”) was screen-printed on the front light-receiving surface side using a printing mask. Subsequently, it dried at 150 degreeC. Subsequently, the same thing was done to the back light-receiving surface side. Then, it heat-processed (baked) at 700 degreeC using the tunnel type | mold baking furnace (made by Noritake Company Limited). The electrode was formed when the composition for silver electrode formation fired through to the passivation layer at the time of baking. As a result, the electrode was in ohmic contact with the n ⁺ -type diffusion layer and the p ⁺ -type diffusion layer to produce a double-sided light-receiving solar cell element.

  One hour after producing the double-sided light-receiving solar cell element, the power generation characteristics were evaluated using a solar cell element solar simulator ("XS-155S-10" manufactured by Wacom Denso Co., Ltd.). The power generation performance is evaluated by using artificial sunlight (“WXS-155S-10” manufactured by Wacom Denso Co., Ltd.) and a voltage-current (IV) evaluation measuring instrument (“E-V CURVE TRACER” manufactured by Eihiro Seiki Corporation MP-180 ") was combined. Jsc (short circuit current density), Voc (open circuit voltage), FF (form factor), and η (conversion efficiency) indicating the power generation performance as a solar cell are based on JIS-C-8913 and JIS-C-8914, respectively. It was obtained by measuring. The results are shown in Table 2.

Moreover, the produced double-sided light-receiving solar cell element was placed in a constant temperature and humidity layer at 50 ° C. and 80% RH, and power generation characteristics after storage for 1 month were evaluated. The results are shown in Table 3. The rate of change in conversion efficiency after storage of the double-sided light-receiving solar cell element (conversion efficiency η ² [%] after storage relative to conversion efficiency η ¹ before storage) was 99.1%.

<Example 2> (Preparation of a composition for forming a passivation layer)
Ta ₂ O ₅ thin film coating material (manufactured by Kojundo Chemical Laboratory, “Ta-10-P”, Ta ₂ O ₅ : 10 mass%, n-octane: 9 mass%, n-butyl acetate: 60 mass% , Stabilizer: 21% by mass) was used as composition 2 for forming a passivation layer.

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

  A double-sided light-receiving solar cell element was prepared in the same manner as in Example 1 except that the passivation layer forming composition 2 was used instead of the passivation layer forming composition 1, and power generation characteristics were evaluated.

<Example 3>
HfO ₂ thin film coating material (manufactured by Kojundo Chemical Laboratory Co., Ltd., “Hf-05”, HfO ₂ content: 5 mass%, isoamyl acetate: 73 mass%, n-octane: 10 mass%, 2-propanol: 5 Mass%, stabilizer: 7 mass%) was used as composition 3 for forming a passivation layer.

An evaluation substrate was prepared in the same manner as in Example 1 except that the passivation layer forming composition 3 prepared above was used, and evaluated in the same manner as in Example 1. The effective lifetime was 380 μs. The thickness of the passivation layer was 71 nm and the density was 3.2 g / cm ³ .

  A double-sided light-receiving solar cell element was prepared in the same manner as in Example 1 except that the passivation layer forming composition 3 was used instead of the passivation layer forming composition 1, and power generation characteristics were evaluated.

<Example 4>
Y ₂ O ₃ thin film coating material (manufactured by Kojundo Chemical Laboratory Co., Ltd., “Y-03”, Y ₂ O ₃ : 3% by mass, 2-ethylhexanoic acid: 12.5% by mass, n-butyl acetate: 22 0.5% by mass, ethyl acetate: 8% by mass, terpin oil: 45% by mass, viscosity modifier: 9% by mass) were used as the passivation layer forming composition 4.

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

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

<Example 5>
Ethyl acetoacetate aluminum diisopropylate (manufactured by Kawaken Fine Chemical Co., Ltd., “ALCH”), pentaethoxyniobium (manufactured by Hokuko Chemical Co., Ltd.), acetylacetone (manufactured by Wako Pure Chemical Industries, Ltd.), xylene (Wako Pure Chemical Industries, Ltd.) Company), 2-propanol (manufactured by Wako Pure Chemical Industries, Ltd.), and terpineol (manufactured by Nippon Terpene Chemical Co., Ltd.) were mixed at the compounding ratio shown in Table 1, and used as composition 5 for forming a passivation layer.

A passivation layer was formed on a pretreated silicon substrate and evaluated in the same manner as in Example 1 except that the composition 5 for forming a passivation layer prepared above was used. The effective lifetime was 420 μs. The thickness of the passivation layer was 94 nm and the density was 2.6 g / cm ³ .

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

<Comparative Example 1>
In Example 1, an evaluation substrate and a solar cell element were produced in the same manner as in Example 1, except that the passivation layer forming composition 1 was not applied. The effective lifetime of the evaluation substrate was measured and evaluated. The effective lifetime was 20 μs.

<Comparative example 2>
In a 3 L separable flask, 100 g of ethylcellulose and 900 g of terpineol were weighed and stirred in air at 150 ° C. as they were. Ethylcellulose was almost dissolved in about 2 hours, and further stirred for 1 hour to obtain a light brown transparent 10% ethylcellulose terpineol solution.
3.00 g of Al ₂ O ₃ particles (manufactured by High Purity Chemical Laboratory, “ALO14PB”, average particle size 1 μm), 2.95 g of terpineol (manufactured by Nippon Terpene Chemical Co., Ltd.), A colorless and transparent composition C2 was prepared by mixing 5.90 g.
A substrate for evaluation 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 lifetime was 21 μs. The thickness of the passivation layer was 2.1 μm, and the density was 1.4 g / cm ³ . Here, since the film thickness could not be measured with an interference film thickness meter, the film thickness was measured with a stylus step meter (“XP-2” manufactured by AmBios). Specifically, a part of the substrate was scraped off with a spatula, and the level difference between the applied portion and the scraped 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 film thickness.
A double-sided light-receiving 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 a passivation layer, and the power generation characteristics were evaluated.

<Comparative Example 3>
A colorless and transparent composition comprising 3.00 g of tetraethoxysilane (manufactured by Tama Chemical Industries), 1.95 g of terpineol (manufactured by Nippon Terpene Chemical Co., Ltd.), and 4.05 g of an ethyl cellulose solution prepared in the same manner as in Comparative Example 2. Product C3 was prepared.
An evaluation substrate was prepared in the same manner as in Example 1 except that the composition C3 prepared above was used, and evaluated in the same manner as in Example 1. The effective lifetime was 23 μs. The thickness of the passivation layer was 85 nm and the density was 2.1 g / cm ³ .
A double-sided light-receiving solar cell element was produced in the same manner as in Example 1 except that the composition C3 was used instead of the composition 1 for forming a passivation layer, and power generation characteristics were evaluated.

In Examples 1 to 6 having the passivation layer of the specific metal oxide, the effective lifetime is longer than 380 to 480 μs and 20 to 23 μs of Comparative Examples 1 to 3, and the conversion efficiency is low because the recombination rate of minority carriers is slow. It can be made high with 14.1-15.76% of an Example with respect to 12.27-12.43% of a comparative example. Further, by providing a passivation layer of a specific metal oxide, the moisture resistance is improved, and the conversion efficiency after being stored at 50 ° C. and 80% RH for one month is maintained at about 98%, whereas in the comparative example, It is about 90%, and a decrease in conversion efficiency over time is suppressed.
From the above, it can be seen that the double-sided solar cell element of the present invention has a passivation layer having an excellent passivation effect, and thus exhibits high conversion efficiency and suppresses deterioration of solar cell characteristics over time. . Furthermore, it turns out that the passivation layer of the double-sided light-receiving solar cell element of the present invention can be formed in a desired shape by a simple process.

10 n type semiconductor substrate 1 p ⁺ type diffusion layer 2 n ⁺ type diffusion layer 3 first passivation layer 4 first passivation layer 5 second passivation layer 6 p type electrode 7 n type electrode

Claims (18)

A semiconductor substrate having a front light receiving surface and a back light receiving surface opposite to the front light receiving surface;
A light receiving surface electrode disposed on the front light receiving surface and the back light receiving surface;
A group consisting of Nb ₂ O ₅ , Ta ₂ O ₅ , V ₂ O ₅ , Y ₂ O _3, and HfO ₂ disposed on at least one of the front light receiving surface, the back light receiving surface, and the side surface of the semiconductor substrate. A passivation layer containing one or more compounds selected from:
A double-sided light-receiving solar cell element. The double-sided light-receiving solar cell element according to claim 1, wherein the passivation layer further contains Al ₂ O ₃ .   The double-sided solar cell element according to claim 1 or 2, wherein the passivation layer is a heat-treated product of the composition for forming a passivation layer. The composition for forming a passivation layer is 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 a compound represented by the following general formula (I). The double-sided light-receiving solar cell element according to claim 3, comprising at least one compound.
M (OR ¹ ) _m (I)
[In General 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 of 0 to 5. ] The passivation layer forming composition contains at least one selected from the group consisting of further Al ₂ O ₃ and a compound represented by the following formula (II), bifacial according to claim 3 or 4 Type solar cell element.

[In the general formula (II), ^{R 2} each independently represent an alkyl group having 1 to 8 carbon atoms. n represents an integer of 0 to 3. X ² and X ³ each independently represent an oxygen atom or a methylene group. R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. ] The double-sided light-receiving solar cell element according to claim 5, wherein R ² in the general formula (II) is independently an alkyl group having 1 to 4 carbon atoms. The double-sided light-receiving type according to claim 5 or 6, wherein n in the general formula (II) is an integer of 1 to 3, and R ⁵ is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Solar cell element. In the composition for forming a passivation layer, the composition for forming a passivation layer contains one or more aluminum compounds selected from the group consisting of the compound represented by the general formula (II) and Al ₂ O ₃ . The double-sided solar cell element according to any one of claims 5 to 7, wherein a content of the aluminum compound is 0.1 to 80% by mass. The composition for forming a passivation layer contains Nb ₂ O ₅ and one or more niobium compounds selected from the group consisting of compounds in which M in the general formula (I) is Nb, and the composition for forming a passivation layer the total content of the niobium compound in things, Nb ₂ O ₅ is 0.1 to 99.9 mass% in terms of claims 4 to bifacial solar cell element according to any one of claims 8 .   The double-sided light-receiving solar cell element according to any one of claims 3 to 9, wherein the composition for forming a passivation layer further contains a liquid medium.   The double-sided solar cell element according to claim 10, wherein the liquid medium contains at least one selected from a hydrophobic organic solvent, an aprotic organic solvent, a terpene solvent, an ester solvent, an ether solvent, and an alcohol solvent. The double-sided light-receiving solar cell element according to any one of claims 1 to 11, wherein a density of the passivation layer is 1.0 to 10.0 g / cm ³ .   The double-sided light-receiving solar cell element according to any one of claims 1 to 12, wherein an average thickness of the passivation layer is 5 nm to 50 µm. Forming a light receiving surface electrode on the front light receiving surface and the back light receiving surface of the semiconductor substrate;
Nb ₂ O ₅ , Ta ₂ O ₅ , V ₂ O ₅ , Y ₂ O ₃ , HfO ₂ and the following general formula (I) are represented on at least one of the front light receiving surface, the back light receiving surface and the side surface. Forming a composition layer by applying a composition for forming a passivation layer containing one or more compounds selected from the group consisting of:
Heat-treating the composition layer to form a passivation layer;
The manufacturing method of the double-sided light reception type solar cell element which has this.
M (OR ¹ ) _m (I)
[In General 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 of 0 to 5. ] The passivation layer forming composition, bifacial of claim 14 which further comprise one or more aluminum compounds selected from the group consisting of the following compound represented by general formula (II) and Al ₂ O ₃ Type solar cell element manufacturing method.

[In the general formula (II), ^{R 2} each independently represent an alkyl group having 1 to 8 carbon atoms. n represents an integer of 0 to 3. X ² and X ³ each independently represent an oxygen atom or a methylene group. R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. ]   The method for manufacturing a double-sided light-receiving solar cell element according to claim 14 or 15, wherein a temperature of the heat treatment is 400 ° C or higher.   The process of forming the said composition layer includes providing the said composition for formation of a passivation layer by the spin coat method, the screen printing method, or the inkjet method, Both surfaces as described in any one of Claims 14-16. A method for manufacturing a light-receiving solar cell element. The double-sided light-receiving solar cell element according to any one of claims 1 to 13,
A wiring material disposed on the electrode of the double-sided light-receiving solar cell element;
A double-sided light-receiving solar cell module.

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