JP2016051848A - Composition for forming passivation layer, semiconductor substrate with passivation layer and method of manufacturing the same, solar cell element and method of manufacturing the same, and solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for forming a passivation layer which allows for formation of a passivation layer excellent in patternability and passivation effect, by a simple technique.SOLUTION: A composition for forming a passivation layer contains niobium alkoxide represented by Nb(OR)(in the formula, Rrepresents an alkyl group or an aryl group, independently), and water.SELECTED DRAWING: Figure 1

Description

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

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 increase the efficiency, and then in a mixed gas atmosphere of phosphorus oxychloride (POCl ₃ ), nitrogen and oxygen, 800 ° C. to 900 ° C. 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 powder 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, the electrical conductivity of the aluminum electrode formed from the aluminum paste is low. In order to reduce the sheet resistance, the aluminum electrode generally formed on the entire back surface must have a thickness of about 10 μm to 20 μm after heat treatment (firing). 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 (firing) and cooling in the silicon substrate on which the aluminum electrode is formed, and the grain boundary Cause damage, crystal defect growth, and warping.

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

In relation to the above, a point contact technique has been proposed in which an aluminum paste is applied to a part of the surface of a silicon substrate to partially form a p ⁺ -type diffusion layer and an aluminum electrode (for example, see Patent Document 1). ).
In the case of a solar cell having a point contact structure on the surface opposite to the light receiving surface (hereinafter also referred to as “back surface”), it is necessary to suppress the recombination rate of minority carriers on the surface of the portion other than the aluminum electrode. is there. For this purpose, a SiO ₂ film or the like has been proposed as a passivation layer for the back surface (see, for example, 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 a method such as an ALD (Atomic Layer Deposition) method or a CVD (Chemical Vapor Deposition) method (for example, see Non-Patent Document 1). 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. 3107287 Japanese Patent Laid-Open No. 2004-6565 Japanese Patent No. 4767110

Journal of Applied Physics, 104 (2008), 113703-1 to 113703-7. Thin Solid Films, 517 (2009), 6327-6330 Chinese Physics Letters, 26 (2009), 088102-1 to 088102-4

  Since the method described in Non-Patent Document 1 includes complicated manufacturing processes such as vapor deposition, it may be difficult to improve productivity. Moreover, in the composition for forming a passivation layer used in the methods described in Non-Patent Documents 2 and 3, since the spin coating method is included in the manufacturing process, it may be difficult to form a film in a target pattern in a short process. .

  The present invention has been made in view of the above-described conventional problems, and provides a composition for forming a passivation layer capable of forming a passivation layer having an excellent pattern forming property and an excellent passivation effect by a simple method. The task is to do. In addition, the present invention provides a semiconductor substrate with a passivation layer, which is obtained using the composition for forming a passivation layer of the present invention and has a passivation layer having an excellent passivation effect, a manufacturing method thereof, and a solar cell having excellent conversion efficiency. It is an object to provide an element, a manufacturing method thereof, and a solar cell.

<1> A composition for forming a passivation layer, comprising a compound represented by the following general formula (I) and water.
Nb (OR ¹ ) ₅ (I)
[In General Formula (I), each R ¹ independently represents an alkyl group or an aryl group. ]

<2> A composition for forming a passivation layer, comprising a hydrolyzate of a compound represented by the following general formula (I).
Nb (OR ¹ ) ₅ (I)
[In General Formula (I), each R ¹ independently represents an alkyl group or an aryl group. ]

<3> The composition for forming a passivation layer according to <1> or <2>, wherein at least one of R ^{1 in} the compound represented by the general formula (I) is an ethyl group.

<4> The composition for forming a passivation layer according to any one of <1> to <3>, further comprising a compound represented by the following general formula (II).

[In General Formula (II), each R ² independently represents an alkyl group. n represents an integer of 1 to 3. X ² and X ³ each independently represent an oxygen atom or a methylene group. R ³ , R ⁴ and R ⁵ each independently represents a hydrogen atom or an alkyl group. ]

<5> Passivation which is a heat treatment product of the composition for forming a passivation layer according to any one of <1> to <4>, provided on at least a part of at least one surface of the semiconductor substrate. And a passivation layer-attached semiconductor substrate.

<6> forming a composition layer by applying the passivation layer forming composition according to any one of <1> to <4> to at least a part of at least one surface of the semiconductor substrate; And a step of forming a passivation layer by heat-treating the composition layer.

<7> Any one of <1> to <4>, provided on a semiconductor substrate having a pn junction formed by pn junction of a p-type layer and an n-type layer, and at least a part of at least one surface of the semiconductor substrate A passivation layer that is a heat-treated product of the composition for forming a passivation layer according to claim 1, an electrode disposed on at least one of the p-type layer and the n-type layer,
A solar cell element having

<8> Passivation according to any one of <1> to <4>, in at least a part of at least one surface of a semiconductor substrate having a pn junction formed by pn junction of a p-type layer and an n-type layer. A step of forming a composition layer by applying a composition for forming a layer; a step of heat-treating the composition layer to form a passivation layer; and on at least one of the p-type layer and the n-type layer. And a step of arranging the electrodes.

<9> A solar cell comprising the solar cell element according to <7>, and a wiring material disposed on the electrode of the solar cell element.

  ADVANTAGE OF THE INVENTION According to this invention, the composition for passivation layer formation which can form the passivation layer excellent in the pattern formation property and excellent in the passivation effect by a simple method can be provided. Further, according to the present invention, a semiconductor substrate with a passivation layer, which is obtained using the composition for forming a passivation layer of the present invention and has a passivation layer having an excellent passivation effect, a method for manufacturing the same, and a solar having excellent conversion efficiency A battery element, a manufacturing method thereof, and a solar battery can be provided.

It is sectional drawing which shows typically an example of the manufacturing method of the solar cell element which has a passivation layer which concerns on this embodiment. It is sectional drawing which shows typically another example of the manufacturing method of the solar cell element which has a passivation layer which concerns on this embodiment. It is sectional drawing which shows typically another example of the manufacturing method of the solar cell element which has a passivation layer which concerns on this embodiment. It is a schematic plan view which shows an example of the light-receiving surface of the solar cell element of this embodiment. It is a schematic plan view which shows an example of the formation pattern in the back surface of the passivation layer which concerns on this embodiment. It is a schematic plan view which shows another example of the formation pattern in the back surface of the passivation layer which concerns on this embodiment. It is the schematic plan view to which the A section of FIG. 5 was expanded. It is the schematic plan view to which the B section of FIG. 5 was expanded. It is a schematic plan view which shows an example of the back surface of the solar cell element of this embodiment. It is a figure for demonstrating an example of the manufacturing method of the solar cell of this embodiment.

  In this specification, the term “process” is not limited to an independent process, and is included in this term if the purpose of the process is achieved even when it cannot be clearly distinguished from other processes. Moreover, the numerical range shown using "to" shows the range which includes the numerical value described before and behind "to" as a minimum value and a maximum value, respectively. Furthermore, the content of each component in the composition means 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. In addition, in the present specification, the term “layer” includes a configuration of a shape formed in part in addition to a configuration of a shape formed on the entire surface when observed as a plan view.

<Composition for forming a passivation layer>
The first composition for forming a passivation layer of the present invention contains a compound represented by the following general formula (I) (hereinafter also referred to as niobium alkoxide) and water. Moreover, the 2nd composition for passivation layer formation of this invention contains the hydrolyzate of niobium alkoxide. In the present invention, the first passivation layer forming composition and the second passivation layer forming composition may be collectively referred to simply as a passivation layer forming composition.
The composition for forming a passivation layer of the present invention may further contain other components as necessary. When the composition for forming a passivation layer of the present invention contains the above components, it is possible to form a passivation layer having excellent pattern forming properties and excellent passivation effect by a simple technique.

Nb (OR ¹ ) ₅ (I)

In the formula, each R ¹ independently represents an alkyl group or an aryl group.

As a result of intensive studies, the present inventor has found that although the mechanism is not clear, the thixotropy of the composition is improved by allowing water to act on the niobium alkoxide.
The first composition for forming a passivation layer contains niobium alkoxide and water, and by allowing water to act on the niobium alkoxide, the composition for forming a passivation layer has a high shear rate and low shear. The viscosity ratio at speed, that is, the thixo ratio is improved. On the other hand, the second composition for forming a passivation layer contains a hydrolyzate of niobium alkoxide, and the hydrolyzate is prepared by allowing water to act on the niobium alkoxide. Similar to the first passivation layer forming composition, the second passivation layer forming composition has water acting on the niobium alkoxide, so that the thixo ratio of the passivation layer forming composition is improved. . As a result, it is surmised that the composition for forming a passivation layer of the present invention is excellent in pattern formability.

  The composition for forming a passivation layer of the present invention improves the thixotropy by allowing water to act on niobium alkoxide, and is a composition layer formed by applying the composition for forming a passivation layer on a semiconductor substrate. Shape stability is further improved, and a passivation layer can be formed in a desired shape in the region where the composition layer is formed. Therefore, in the composition for forming a passivation layer of the present invention, at least one of a thixotropic agent and a resin described later (hereinafter, at least one of the thixotropic agent and the resin is referred to as a thixotropic agent or the like) in order to express desired thixotropic properties. Even if a thixotropic agent or the like is used, the amount added can be reduced as compared with the conventional passivation layer-forming composition.

  When forming a passivation layer using a composition for forming a passivation layer containing a thixotropic agent composed of an organic substance, the thixotropic agent is thermally decomposed and scattered from the passivation layer through a degreasing process. Become. However, a thermal decomposition product such as a thixotropic agent may remain as an impurity in the passivation layer even after the degreasing step, and the remaining thermal decomposition product such as a thixotropic agent may cause deterioration of the characteristics of the passivation layer. On the other hand, when forming a passivation layer using a composition for forming a passivation layer containing a thixotropic agent composed of an inorganic substance, the thixotropic agent does not scatter and remains in the passivation layer even after a heat treatment (firing) step. The remaining thixotropic agent may cause deterioration of the characteristics of the passivation layer.

  On the other hand, in the composition for forming a passivation layer of the present invention, when water acts on the niobium alkoxide, water or a hydrolyzate of niobium alkoxide behaves as a thixotropic agent. Water is more likely to scatter from the passivation layer than a conventional thixotropic agent or the like in a heat treatment (firing) step or the like that is performed when the passivation layer is formed using the passivation layer forming composition. For this reason, it is difficult to cause a decrease in the passivation effect of the passivation layer due to the presence of the residue in the passivation layer.

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

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

1 / τ = 1 / τ _b + 1 / τ _s (A)

  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.

(Niobium alkoxide)
The first composition for forming a passivation layer contains at least one niobium alkoxide. The second passivation layer-forming composition contains at least one hydrolyzate of niobium alkoxide. When the composition for forming a passivation layer of the present invention contains at least one niobium alkoxide or a hydrolyzate thereof, a passivation layer having an excellent passivation effect can be formed. The reason can be considered as follows.

  A metal oxide formed by heat-treating (firing) a composition for forming a passivation layer containing niobium alkoxide or a hydrolyzate thereof is considered to have defects of metal atoms or oxygen atoms and easily generate fixed charges. It is done. When this fixed charge generates charge near the interface of the semiconductor substrate, the concentration of minority carriers can be reduced. As a result, the carrier recombination rate at the interface is suppressed, and an excellent passivation effect is achieved. Conceivable.

  Here, as for the state of the passivation layer that generates a fixed charge on the semiconductor substrate, the cross section of the semiconductor substrate is subjected to electron transmission loss electron spectroscopy (EELS, Electron Energy Loss Spectroscopy) using a Scanning Transmission Electron Microscope (STEM, Scanning Transmission Electron Microscope). It can be evaluated by examining the binding mode in the analysis of). In addition, by measuring an X-ray diffraction spectrum (XRD, X-ray diffraction), the crystal phase near the interface of the passivation layer can be confirmed. Furthermore, the fixed charge of the passivation layer can be evaluated by a CV method (Capacitance Voltage measurement).

In the general formula (I), each R ¹ independently represents an alkyl group or an aryl group, preferably an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms, and an alkyl group having 1 to 8 carbon atoms. Are more preferable, and an alkyl group having 1 to 4 carbon atoms is more preferable. The alkyl group represented by R ¹ may be linear or branched.
Specific examples of the alkyl group represented by R ¹ include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, Examples include a hexyl group, an octyl group, a 2-ethylhexyl group, and a 3-ethylhexyl group.
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 include methyl group, ethyl group, i-propyl group, amino group, hydroxy group, carboxy group, sulfo group. Group, nitro group and the like.
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 reactivity with water and a passivation effect. Preferably, it is an ethyl group.

Niobium alkoxide is preferably R ¹ is niobium alkoxide an unsubstituted alkyl group having 1 to 4 carbon atoms, more preferably at least one of R ¹ is a niobium alkoxide is ethyl, for R ¹ More preferred are niobium alkoxides (niobium ethoxide), all of which are ethyl groups. When the composition for forming a passivation layer contains niobium ethoxide, a more excellent pattern forming property and a higher passivation effect can be obtained.

  The state of niobium alkoxide may be solid or liquid at normal temperature (25 ° C.). From the viewpoint of storage stability of the composition for forming a passivation layer of the present invention, miscibility with water, and miscibility in the case of using a compound represented by formula (II) or formula (III) described later in combination, niobium alkoxide. Is preferably liquid at 25 ° C.

  Specific examples of niobium alkoxide include niobium methoxide, niobium ethoxide, niobium i-propoxide, niobium n-propoxide, niobium n-butoxide, niobium t-butoxide, niobium i-butoxide, and the like. Niobium ethoxide, niobium n-propoxide and niobium n-butoxide are preferred, and niobium ethoxide is more preferred.

  As the niobium alkoxide, 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 from High Purity Chemical Laboratory Co., Ltd. And penta-sec-butoxyniobium.

  Niobium alkoxide is prepared by reacting niobium halide and alcohol in the presence of an inert organic solvent, and further adding ammonia or amines to extract halogen (Japanese Patent Laid-Open No. 63-227593 and JP-A-63-227593). Known manufacturing methods such as JP-A-3-291247) can be used.

  A part of the niobium alkoxide may be contained in the composition for forming a passivation layer of the present invention as a compound having a chelate structure formed by mixing with a compound having a specific structure having two carbonyl groups described later.

  The presence of the alkoxide structure in the niobium alkoxide 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 content of niobium alkoxide contained in the first composition for forming a passivation layer can be appropriately selected as necessary. The content of niobium alkoxide can be 0.1% by mass to 80% by mass in the first composition for forming a passivation layer from the viewpoint of the reactivity with water and the passivation effect, and 0.5% by mass. It is preferably ˜70% by mass, more preferably 1% by mass to 60% by mass, and still more preferably 1% by mass to 50% by mass.

The content of the hydrolyzate of niobium alkoxide contained in the second passivation layer forming composition can be appropriately selected as necessary. The content of the niobium alkoxide hydrolyzate may be 0.1% by mass to 80% by mass in the second composition for forming a passivation layer from the viewpoint of the passivation effect, and 0.5% by mass to 70% by mass. The mass is preferably 1% by mass, more preferably 1% by mass to 60% by mass, and still more preferably 1% by mass to 50% by mass.
In the present invention, the niobium alkoxide hydrolyzate refers to a hydrolysis product of niobium alkoxide obtained by adding water to niobium alkoxide, and the niobium alkoxide hydrolyzate reacts with water. Niobium alkoxide that is not present may remain, or water that has not reacted with the niobium alkoxide may remain.

(water)
The first composition for forming a passivation layer contains water. When the first composition for forming a passivation layer contains water, the composition for forming a passivation layer having excellent pattern forming properties is obtained. The reason can be considered as follows.

  Water reacts at least partially with niobium alkoxide in the first composition for forming a passivation layer. A hydrolyzate of niobium alkoxide, which is a metal compound formed by the reaction of water with niobium alkoxide, is considered to form a network between the metal compounds. Further, it is considered that this network is easily broken when the composition for forming a passivation layer is flowing, and is re-formed when the composition becomes stationary again. This network increases the viscosity when the composition for forming a passivation layer is stationary, and decreases the viscosity when the composition is flowing. As a result, it is considered that the composition for forming a passivation layer develops thixotropy necessary for pattern formation.

  By using a composition for forming a passivation layer having excellent pattern forming properties, a passivation layer having a desired shape can be formed. This makes it possible to manufacture an excellent semiconductor substrate with a passivation layer, a solar cell element, and a solar cell.

  The water state may be solid or liquid. From the viewpoint of miscibility with niobium alkoxide, water is preferably a liquid.

The content rate of water contained in the first composition for forming a passivation layer can be appropriately selected as necessary.
From the viewpoint of imparting thixotropy to the first passivation layer forming composition, the water content can be 0.01% by mass or more in the first passivation layer forming composition. It is preferably at least mass%, more preferably at least 0.05 mass%, and even more preferably at least 0.1 mass%.
Moreover, the content rate of water can be 0.01 mass%-80 mass% in the 1st composition for passivation layer formation from a viewpoint of pattern formation property and a passivation effect, and 0.03 mass%- It is preferably 70% by mass, more preferably 0.05% by mass to 60% by mass, and still more preferably 0.1% by mass to 50% by mass.

In addition, the second composition for forming a passivation layer may contain water. The content rate of water contained in the second composition for forming a passivation layer can be appropriately selected as necessary.
From the viewpoint of imparting thixotropy to the second passivation layer forming composition, the water content can be 0.01% by mass or more in the second passivation layer forming composition. It is preferably at least mass%, more preferably at least 0.05 mass%, and even more preferably at least 0.1 mass%.
The content of water can be 0.01% by mass to 80% by mass in the second composition for forming a passivation layer and 0.03% by mass to 70% by mass from the viewpoint of pattern formability and passivation effect. %, More preferably 0.05% by mass to 60% by mass, and still more preferably 0.1% by mass to 50% by mass.

The amount of water acting on the niobium alkoxide in the composition for forming a passivation layer can be calculated from the amount of alcohol liberated from the niobium alkoxide. When water acts on the niobium alkoxide, alcohol, that is, R ¹ OH is liberated from the niobium alkoxide. The amount of this liberated alcohol is proportional to the number of functional groups of the niobium alkoxide on which water has acted. Therefore, the amount of water that has acted on the niobium alkoxide can be calculated by measuring the amount of the liberated alcohol. The measurement of the amount of alcohol liberated can be confirmed, for example, using gas chromatography mass spectrometry (GC-MS).

  When the niobium alkoxide is niobium ethoxide, ethanol is liberated when water acts. Ethanol has low toxicity to the human body among alcohols. Therefore, by selecting niobium ethoxide as the niobium alkoxide, the material has less adverse effects on the human body.

0.5 mass%-70 mass% are preferable, and, as for the content rate of alcohol contained in the composition for forming a passivation layer, that is, liberated R ¹ OH, 1 mass% to 60 mass% are more preferable, and 1 mass% to 50 mass%. More preferred is mass%.

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

In general formula (II), each R ² independently represents an alkyl group. n represents an integer of 1 to 3. X ² and X ³ each independently represent an oxygen atom or a methylene group. R ³ , R ⁴ and R ⁵ each independently represents a hydrogen atom or an alkyl group.

  The passivation effect can be further improved because the composition for forming a passivation layer of the present invention contains the organoaluminum compound. This can be considered as follows.

The organoaluminum compound includes compounds called aluminum alkoxide, aluminum chelate and the like, and preferably has an aluminum chelate structure in addition to the aluminum alkoxide structure. Also, Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi, vol. 97, pp 369-399 (1989), the organoaluminum compound becomes aluminum oxide (Al ₂ O ₃ ) by heat treatment (firing). At this time, since the formed aluminum oxide is likely to be in an amorphous state, a four-coordinate aluminum oxide layer is easily formed in the vicinity of the interface with the semiconductor substrate, and has a large negative fixed charge caused by the four-coordinate aluminum oxide. It is considered possible. At this time, it is considered that a passivation layer having an excellent passivation effect can be formed by compounding with niobium alkoxide having a fixed charge or an oxide derived from a hydrolyzate thereof.

  In addition to the above, by combining niobium alkoxide or a hydrolyzate thereof and an organoaluminum compound as in the present invention, it is considered that the passivation effect becomes higher due to the respective effects in the passivation layer. Furthermore, the reaction as a composite metal alkoxide of niobium (Nb) and aluminum (Al) contained in niobium alkoxide by heat treatment (firing) in a state where niobium alkoxide or its hydrolyzate and organoaluminum compound are mixed. And physical properties such as vapor pressure are improved, the denseness of the passivation layer as a heat-treated product (baked product) is improved, and as a result, the passivation effect is considered to be higher.

In formula (II), R ² represents an alkyl group independently, preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms. The alkyl group represented by R ² may be linear or branched. Specific examples of the alkyl group represented by R ² include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, Examples include a hexyl group, an octyl group, a 2-ethylhexyl group, and a 3-ethylhexyl group. 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 1 to 3. n is preferably 1 or 3 from the viewpoint of storage stability, and more preferably 1 from the viewpoint of solubility.
X ² and X ³ each independently represent an oxygen atom or a methylene group. From the viewpoint of storage stability, at least one of X ² and X ³ is preferably an oxygen atom.
R ³ , R ⁴ and R ⁵ in the general formula (II) each independently represent a hydrogen atom or an alkyl group. The alkyl group represented by R ³ , R ⁴ and R ⁵ may be linear or branched. The alkyl group represented by R ³ , R ⁴ and R ⁵ is preferably an alkyl group having 1 to 8 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms. Specifically, methyl group, ethyl group, propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, hexyl group, octyl group, 2-ethylhexyl group, A 3-ethylhexyl group etc. can be mentioned.

Among these, from the viewpoint of storage stability and a passivation effect, R ³ and R ⁴ are each independently preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 8 carbon atoms, and preferably a hydrogen atom or 1 to 4 carbon atoms. The unsubstituted alkyl group is more preferable.
R ⁵ 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 an unsubstituted alkyl group having 1 to 4 carbon atoms. More preferably.

From the viewpoint of storage stability, the organoaluminum compound is preferably a compound in which n is an integer of 1 to 3, and R ⁵ is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

From the viewpoint of storage stability and passivation effect, the organoaluminum compound is an integer from 1 to 3, R ² is each independently an alkyl group having 1 to 4 carbon atoms, and at least X ² and X ³ One is an oxygen atom, R ³ and R ⁴ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ⁵ is a compound that is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. It is preferable. In the organoaluminum compound, n is an integer of 1 to 3, R ² is each independently an unsubstituted alkyl group having 1 to 4 carbon atoms, and at least one of X ² and X ³ is an oxygen atom, When R ³ or R ⁴ bonded to the oxygen atom is an alkyl group having 1 to ⁴ carbon atoms and X ² or X ³ is a methylene group, R ³ or R ⁴ bonded to the methylene group is a hydrogen atom. More preferably, R ⁵ is a hydrogen atom.

  Specific examples of the organoaluminum compound represented by the general formula (II) where n is an integer of 1 to 3 include aluminum ethyl acetoacetate di i-propylate and tris (ethyl acetoacetate) aluminum. .

  Moreover, as the organoaluminum compound represented by the general formula (II) and n being an integer 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 represented by the general formula (II) and n is an integer of 1 to 3 is prepared by mixing an aluminum trialkoxide and a compound having a specific structure having two carbonyl groups described later. Can do. A commercially available aluminum chelate compound may also be used.
When an aluminum trialkoxide and a compound having a specific structure having two carbonyl groups are mixed, at least a part of the alkoxide group of the aluminum trialkoxide is substituted with the compound having the specific structure to form an aluminum chelate structure. At this time, if necessary, a liquid medium may be present, and heat treatment, addition of a catalyst, and the like may be performed. By replacing at least a part of the aluminum alkoxide structure with the aluminum chelate structure, the stability of the 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 compound having a specific structure having the two carbonyl groups include acetylacetone, 3-methyl-2,4-pentanedione, 2,3-pentanedione, 3-ethyl-2,4-pentanedione, 3- Butyl-2,4-pentanedione, 2,2,6,6-tetramethyl-3,5-heptanedione, 2,6-dimethyl-3,5-heptanedione, 6-methyl-2,4-heptanedione Β-diketone compounds such as methyl acetoacetate, ethyl acetoacetate, n-propyl acetoacetate, i-propyl acetoacetate, i-butyl acetoacetate, n-butyl acetoacetate, t-butyl acetoacetate, n-pentyl acetoacetate I-pentyl acetoacetate, n-hexyl acetoacetate, n-octyl acetoacetate, n-heptyl acetoacetate, 3-pentyl acetoacetate, 2- Ethyl cetyl heptanoate, ethyl 2-methylacetoacetate, ethyl 2-butylacetoacetate, ethyl hexylacetoacetate, ethyl 4,4-dimethyl-3-oxovalerate, ethyl 4-methyl-3-oxovalerate, 2-ethylacetoacetate Ethyl, methyl 4-methyl-3-oxovalerate, ethyl 3-oxohexanoate, ethyl 3-oxovalerate, methyl 3-oxovalerate, methyl 3-oxohexanoate, ethyl 3-oxoheptanoate, 3- Β-ketoester compounds such as methyl oxoheptanoate, methyl 4,4-dimethyl-3-oxovalerate, dimethyl malonate, diethyl malonate, di-n-propyl malonate, di-i-propyl malonate, di-n malonate -Butyl, di-t-butyl malonate, dihexyl malonate, t-butylethyl malonate, methylmalonic acid Examples include malonic acid diesters such as ethyl, diethyl ethylmalonate, diethyl i-propylmalonate, diethyl n-butylmalonate, diethyl sec-butylmalonate, diethyl i-butylmalonate, diethyl 1-methylbutylmalonate, etc. be able to.

  The number of aluminum chelate structures can be controlled, for example, by appropriately adjusting the ratio of mixing aluminum trialkoxide and a compound having a specific structure having two carbonyl groups. Moreover, you may select suitably the compound which has a desired structure from a commercially available aluminum chelate compound.

  Among organoaluminum compounds, from the viewpoint of the passivation effect and compatibility with the solvent contained as necessary, specifically, at least selected from the group consisting of aluminum ethyl acetoacetate di i-propylate and tri i-propoxy aluminum One type is preferably used, and aluminum ethyl acetoacetate di i-propylate is more preferably used.

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

In the composition for forming a passivation layer of the present invention, when an organoaluminum compound is included, the content of the organoaluminum compound is not particularly limited. Especially, it is preferable that the content rate of an organoaluminum compound when the total content rate of niobium alkoxide or its hydrolyzate, and an organoaluminum compound is 100 mass% is 0.5 mass%-80 mass%. More preferably, it is more preferably from 75% by weight to 75% by weight, even more preferably from 2% to 70% by weight, and particularly preferably from 3% to 70% by weight.
By setting the content of the organoaluminum compound to 0.5% by mass or more, the passivation effect tends to be improved. Moreover, it exists in the tendency for the storage stability of the composition for passivation layer formation to improve by making an organoaluminum compound 80 mass% or less.

  When the composition for forming a passivation layer of the present invention contains an organoaluminum compound, the content of the organoaluminum compound in the composition for forming a passivation layer can be appropriately selected as necessary. The content of the organoaluminum compound can be 0.1% by mass to 60% by mass in the composition for forming a passivation layer, and 0.5% by mass to 55% by mass from the viewpoint of storage stability and a passivation effect. It is preferable that it is 1 mass%-50 mass%, and it is still more preferable that it is 1 mass%-45 mass%.

  The composition for forming a passivation layer of the present invention may contain at least one compound represented by the following general formula (III) (hereinafter referred to as “specific metal alkoxide”).

M (OR ¹ ) _m (III)
[In General Formula (III), M represents at least one selected from the group consisting of Al, Ta, VO, Y, and Hf. R ¹ independently represents an alkyl group or an aryl group. m represents an integer of 1 to 5. ]

In the general formula (III), each R ¹ independently represents an alkyl group or an aryl group, preferably an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms, and an alkyl group having 1 to 8 carbon atoms. Are more preferable, and an alkyl group having 1 to 4 carbon atoms is more preferable. The alkyl group represented by R ¹ may be linear or branched.
Specific examples of the alkyl group represented by R ¹ include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, Examples include a hexyl group, an octyl group, a 2-ethylhexyl group, and a 3-ethylhexyl group.
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 include methyl group, ethyl group, i-propyl group, amino group, hydroxy group, carboxy group, sulfo group. Group, nitro group and the like.
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 reactivity with water and a passivation effect. Preferably, it is an ethyl group.

  In general formula (III), m represents the integer of 1-5. Here, from the viewpoint of reactivity with water, m is preferably 3 when M is Al, m is preferably 5 when M is Ta, and M is VO. In some cases, m is preferably 3, m is preferably 3 when M is Y, and m is preferably 4 when M is Hf.

  The state of the specific metal alkoxide may be solid or liquid at normal temperature (25 ° C.). From the viewpoint of storage stability of the composition for forming a passivation layer of the present invention, miscibility with water, and miscibility with niobium alkoxide or an organoaluminum compound, the specific metal alkoxide is preferably liquid at 25 ° C.

  Specific examples of the specific metal alkoxide include aluminum methoxide, aluminum ethoxide, aluminum i-propoxide, aluminum n-propoxide, aluminum n-butoxide, aluminum t-butoxide, aluminum i-butoxide, tantalum methoxide, and tantalum ethoxy. Tantalum i-propoxide, tantalum n-propoxide, tantalum n-butoxide, tantalum t-butoxide, tantalum i-butoxide, yttrium methoxide, yttrium ethoxide, yttrium i-propoxide, yttrium n-propoxide, yttrium n-butoxide, yttrium t-butoxide, yttrium i-butoxide, vanadium oxymethoxide, vanadium oxyethoxide, vanadium oxy i-pro Oxide, vanadium oxy n-propoxide, vanadium oxy n-butoxide, vanadium oxy t-butoxide, vanadium oxy i-butoxide, hafnium methoxide, hafnium ethoxide, hafnium i-propoxide, hafnium n-propoxide, hafnium n- Examples include butoxide, hafnium t-butoxide, hafnium i-butoxide, and the like.

  As the specific metal alkoxide, a prepared product or a commercially available product may be used. Examples of commercially available products include pentamethoxy tantalum, pentaethoxy tantalum, penta-i-propoxy tantalum, penta-n-propoxy tantalum, penta-i-butoxy tantalum, penta-n-butoxy tantalum manufactured by High Purity Chemical Laboratory Co., Ltd. Penta-sec-butoxy tantalum, penta-t-butoxy tantalum, vanadium (V) trimethoxide oxide, vanadium (V) triethoxy oxide, vanadium (V) tri-i-propoxide oxide, vanadium (V) tri- n-propoxide oxide, vanadium (V) tri-i-butoxide oxide, vanadium (V) tri-n-butoxide oxide, vanadium (V) tri-sec-butoxide oxide, vanadium (V) tri-t-butoxide oxide, Tri-i-propoxy Yttrium, tri-n-butoxy yttrium, tetramethoxy hafnium, tetraethoxy hafnium, tetra-i-propoxy hafnium, tetra-t-butoxy hafnium, Hokuko Chemical Industries, Ltd. pentaethoxy tantalum, pentaboxy tantalum, yttrium n-butoxide , Hafnium-tert-butoxide, vanadium oxytriethoxide, vanadium oxytrinormal propoxide, vanadium oxytrinormal butoxide, vanadium oxytriisobutoxide, vanadium oxytriisobutoxide, vanadium oxytrisecondary butoxide from Nichia Corporation .

  The specific metal alkoxide is prepared by reacting a halide of a specific metal (M) with an alcohol in the presence of an inert organic solvent, and further adding ammonia or amines to extract the halogen (Japanese Patent Laid-Open No. Sho). 63-227593 and JP-A-3-291247) can be used.

  A part of the specific metal alkoxide is contained in the composition for forming a passivation layer of the present invention as a compound in which a chelate structure is formed by mixing with a compound having a specific structure having two carbonyl groups, like niobium alkoxide. Also good.

  The presence of the alkoxide structure in the specific metal alkoxide 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 specific metal alkoxide may be contained in the composition for forming a passivation layer as a hydrolyzate of the specific metal alkoxide. The content rate of the specific metal alkoxide or its hydrolyzate contained in the composition for forming a passivation layer can be appropriately selected as necessary. From the viewpoint of the reactivity with water and the passivation effect, the composition for forming a passivation layer can be 0.1% by mass to 80% by mass, and preferably 0.5% by mass to 70% by mass. The content is more preferably 1% by mass to 60% by mass, and further preferably 1% by mass to 50% by mass.

  In the present invention, the hydrolyzate of the specific metal alkoxide refers to a hydrolysis product of the hydrolysis of the specific metal alkoxide obtained by adding water to the specific metal alkoxide. In the hydrolyzate of the specific metal alkoxide, The specific metal alkoxide that has not reacted with water may remain, or water that has not reacted with the specific metal alkoxide may remain.

(Liquid medium)
The composition for forming a passivation layer of the present invention may contain a liquid medium (solvent or dispersion medium). When the composition for forming a passivation layer contains a liquid medium, the viscosity can be easily adjusted, the impartability can be further improved, and a more uniform passivation layer can be formed. The liquid medium is not particularly limited and can be appropriately selected as necessary. Among these, a liquid medium capable of dissolving niobium alkoxide and an organoaluminum compound or a specific metal alkoxide added as necessary to give a uniform solution is preferable, and more preferably containing at least one organic solvent. A liquid medium means a medium in a liquid state at room temperature (25 ° C.).

  Specific examples of the liquid medium include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl i-propyl ketone, methyl-n-butyl ketone, methyl i-butyl ketone, methyl-n-pentyl ketone, methyl-n-hexyl ketone, Ketone solvents such as diethyl ketone, di-n-propyl ketone, di-butyl ketone, trimethylnonanone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, diethyl ether, methyl ethyl ether, methyl -N-propyl ether, di-propyl ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, dimethyldioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol Cold di-n-propyl ether, ethylene glycol di n-butyl 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 glycol Methyl-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 di n-butyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene Glycol methyl ethyl ether, dipropylene Glycol methyl-n-butyl ether, dipropylene glycol di-n-propyl ether, dipropylene glycol di-n-butyl ether, dipropylene glycol methyl-n-hexyl ether, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, tripropylene glycol Methyl ethyl ether, tripropylene glycol methyl-n-butyl ether, tripropylene glycol di-n-butyl ether, tripropylene glycol methyl-n-hexyl ether, tetrapropylene glycol dimethyl ether, tetrapropylene glycol diethyl ether, tetrapropylene glycol methyl ethyl ether, Tetrapropylene glycol methyl-n-butyl ether, tetrap Ether solvents such as pyrene glycol di-n-butyl ether, tetrapropylene glycol methyl-n-hexyl ether, tetrapropylene glycol di-n-butyl ether, methyl acetate, ethyl acetate, n-propyl acetate, i-propyl acetate, n-acetate Butyl, i-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, 2- (2-butoxyethoxy acetate) ) Ethyl, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, nonyl acetate, methyl acetoacetate, ethyl acetoacetate, diethylene glycol methyl ether acetate, diethylene glycol monoethyl ether acetate, dipropylene glycol methyl acetate Ether, dipropylene glycol ethyl ether, glycol diacetate, methoxytriethylene glycol acetate, i-amyl acetate, ethyl propionate, n-butyl propionate, i-amyl propionate, diethyl oxalate, di-n-oxalate Butyl, 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 Esters such as acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether acetate, γ-butyrolactone, γ-valerolactone, etc. , Acetonitrile, N-methylpyrrolidinone, N-ethylpyrrolidinone, Nn-propylpyrrolidinone, Nn-butylpyrrolidinone, Nn-hexylpyrrolidinone, N-cyclohexylpyrrolidinone, N, N-dimethylformamide, N, N- Aprotic polar solvents such as dimethylacetamide and dimethylsulfoxide, hydrophobic organic solvents such as methylene chloride, chloroform, dichloroethane, benzene, toluene, xylene, hexane, octane, ethylbenzene, 2-ethylhexanoic acid, methanol, ethanol, n- Propanol, i-propanol, n-butanol, i-butanol, sec-butanol, t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, sec-pentanol, t-pentanol , 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, n-decanol , Sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, phenol, cyclohexanol, methylcyclohexanol, benzyl alcohol, ethylene glycol, 1,2-propylene glycol, 1,3-butylene Alcohol solvents such as glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, 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, aloocimene, limonene, dipentene, pinene, carvone, osymene, ferrolandene, etc. Terpene solvent It is. These liquid media are used alone or in combination of two or more.

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

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

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

The type of resin is not particularly limited. The resin 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 of the present invention is applied on a semiconductor substrate. Specific examples of the resin include polyvinyl alcohol, polyacrylamide, polyacrylamide derivatives, polyvinylamide, polyvinylamide derivatives, polyvinylpyrrolidone, polyethylene oxide, polyethylene oxide derivatives, polysulfonic acid, polyacrylamide alkylsulfonic acid, cellulose, and cellulose derivatives (carboxymethylcellulose). , Cellulose ethers such as hydroxyethyl cellulose and ethyl cellulose), gelatin, gelatin derivatives, starch, starch derivatives, sodium alginate, sodium alginate derivatives, xanthan, xanthan derivatives, guar gum, guar gum derivatives, scleroglucan, scleroglucan derivatives, tragacanth, Tragacanth derivative, dextrin, dextrin derivative, (meta) Examples include crylic acid resin, (meth) acrylic acid ester resin (alkyl (meth) acrylate resin, dimethylaminoethyl (meth) acrylate resin, etc.), butadiene resin, styrene resin, siloxane resin, and copolymers thereof. . These resins are used singly or in combination of two or more.
In the present invention, (meth) acryl represents acryl or methacryl, and (meth) acrylate represents acrylate or methacrylate.

Among these resins, from the viewpoint of storage stability and pattern formation, it is preferable to use a neutral resin having no acidic or basic functional group, and even when the content is small, viscosity and From the viewpoint of adjusting the thixotropy, it is more preferable to use a cellulose derivative.
Further, the molecular weight of these resins is not particularly limited, and it is preferable to adjust appropriately in view of the desired viscosity as the composition for forming a passivation layer. The weight average molecular weight of the resin is preferably 1000 to 10,000,000, and more preferably 1,000 to 5,000,000, from the viewpoints of storage stability and pattern formation. In addition, the weight average molecular weight of resin is calculated | required by converting using the analytical curve of a standard polystyrene from the molecular weight distribution measured using GPC (gel permeation chromatography).

When the composition for forming a passivation layer of the present invention contains a resin, the content of the resin in the composition for forming a passivation layer can be appropriately selected as necessary. For example, the resin content is preferably 0.1% by mass to 50% by mass in the total mass of the composition for forming a passivation layer. From the viewpoint of expressing thixotropy that facilitates pattern formation, the resin content is more preferably 0.2% by mass to 25% by mass, and 0.5% by mass to 20% by mass. Is more preferable, and it is particularly preferably 0.5% by mass to 15% by mass.
In addition, since the composition for forming a passivation layer of the present invention is excellent in thixotropy, it is not necessary to develop thixotropy with a resin. Therefore, the content of the resin contained in the composition for forming a passivation layer of the present invention is preferably 0.5% by mass or less, more preferably 0.2% by mass or less, still more preferably 0.1% by mass or less, and substantially It is particularly preferable that no resin is contained.

(Other ingredients)
The composition for forming a passivation layer of the present invention may further contain other components that are usually used in the art as needed, in addition to the components described above.
The composition for forming a passivation layer of the present invention 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 is 1% by mass or less in the composition for forming a passivation layer, respectively. It is preferable that the content is 0.1% by mass or less.
Examples of acidic compounds include Bronsted acid and Lewis acid. Specific examples include inorganic acids such as hydrochloric acid and nitric acid, and organic acids such as acetic acid. Examples of basic compounds include Bronsted bases and Lewis bases. Specifically, examples of the basic compound include inorganic bases such as alkali metal hydroxides and alkaline earth metal hydroxides, and organic bases such as trialkylamine and pyridine.

  Examples of other components include plasticizers, dispersants, surfactants, thixotropic agents, other metal alkoxide compounds, and high-boiling materials.

  Examples of the thixotropic agent include fatty acid amides, polyalkylene glycol compounds, organic fillers, and inorganic fillers. Examples of the polyalkylene glycol compound include compounds represented by the following general formula (IV).

R ⁶ — (O—R ⁸ ) _n —O—R ⁷ (IV)

In general formula (IV), R ⁶ and R ⁷ each independently represent a hydrogen atom or an alkyl group, and R ⁸ represents an alkylene group. n is an arbitrary integer of 3 or more. Incidentally, R ⁸ in the presence of a plurality of (O-R ⁸⁾ may or may not be the same.

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

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

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

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

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

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

  Examples of other metal alkoxide compounds include titanium alkoxide, zirconium alkoxide, and silicon alkoxide.

(High boiling point material)
In the composition for forming a passivation layer of the present invention, a high boiling point material may be used together with the resin or as a material replacing the resin. The high boiling point material is preferably a compound that is easily vaporized when heated and does not need to be degreased. The high boiling point material is particularly preferably a high boiling point material having a high viscosity capable of maintaining a printed shape after printing and coating. An example of a material that satisfies these conditions is isobornylcyclohexanol.

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

  When the composition for forming a passivation layer of the present invention contains a high boiling point material, the content of the high boiling point material is preferably 3% by mass to 95% by mass in the total mass of the composition for forming a passivation layer, More preferably, it is 5 mass%-90 mass%, and it is still more preferable that it is 7 mass%-80 mass%.

  The composition for forming a passivation layer of the present invention contains at least one oxide selected from the group consisting of Al, Nb, Ta, V, Y, and Hf (hereinafter referred to as “specific oxide”). May be. The specific oxide is preferably an oxide formed by heat treatment (firing) at least one metal alkoxide selected from the group consisting of Al, Nb, Ta, V, Y, and Hf. A passivation layer formed from such a composition for forming a passivation layer containing a specific oxide is expected to exhibit an excellent passivation effect.

The viscosity of the composition for forming a passivation layer of the present invention is not particularly limited, and can be appropriately selected depending on a method for applying the composition to a semiconductor substrate. For example, the viscosity of the composition for forming a passivation layer can be 0.01 Pa · s to 100,000 Pa · s. Among these, from the viewpoint of pattern formability, the viscosity of the composition for forming a passivation layer is preferably 0.1 Pa · s to 10000 Pa · s. The viscosity is measured at 25 ° C. and a shear rate of 1.0 s ⁻¹ using a rotary shear viscometer equipped with a cone plate (diameter 50 mm, cone angle 1 °).

The thixo ratio of the composition for forming a passivation layer of the present invention is not particularly limited, and can be appropriately selected according to a method for applying to a semiconductor substrate. For example, shear rate 0.1s ^-1 Viscosity is measured by η1 a (Pa · s), a thixotropic ratio is calculated by dividing the viscosity measured at a shear rate of ^{10.0s -1 η2 (Pa · s)} ( (η1 / η2) is preferably from 1.05 to 100, more preferably from 1.1 to 50. The shear viscosity is measured at 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 passivation layer formation of this invention. For example, it can be manufactured by mixing niobium alkoxide, water, and an organoaluminum compound, a specific metal alkoxide, a liquid medium, a resin, and the like that are included as necessary by a commonly used mixing method.
In addition, the components contained in the composition for forming a passivation layer of the present invention, and the content of each component include thermal analysis such as TG / DTA, spectrum analysis such as NMR and IR, and chromatographic analysis such as HPLC and GPC. Can be confirmed.

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

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

  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 μm to 1000 μm, and preferably 75 μm to 750 μm.

The thickness of the passivation layer formed on the semiconductor substrate is not particularly limited and can be appropriately selected depending on the purpose. For example, the thickness is preferably 5 nm to 50 μm, more preferably 10 nm to 30 μm, and still more preferably 15 nm to 20 μm.
In addition, the average thickness of the formed passivation layer was measured by measuring the thickness at three points by an ordinary method using an interference film thickness meter (for example, Filmetrics F20 film thickness measurement system), and the arithmetic average value thereof Calculated.

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

<Method for manufacturing semiconductor substrate with passivation layer>
The method for producing a semiconductor substrate with a passivation layer of the present invention comprises a step of forming a composition layer by applying the composition for forming a passivation layer of the present invention to at least a part of at least one surface of a semiconductor substrate, and the composition Forming a passivation layer by heat-treating (baking) the physical layer. The manufacturing method may further include other steps as necessary.
By using the composition for forming a passivation layer of the present invention, a passivation layer having excellent pattern forming properties and an excellent passivation effect can be formed by a simple method.

  The method for producing a semiconductor substrate with a passivation layer of the present invention preferably further includes a step of applying an alkaline aqueous solution on the semiconductor substrate before the step of forming the 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 of the present invention on the semiconductor substrate. By washing with an alkaline aqueous solution, organic substances, particles, and the like present on the surface of the semiconductor substrate can be removed, and the passivation effect is further improved. As a cleaning method using an alkaline aqueous solution, a generally known cleaning method using RCA cleaning or the like can be exemplified. For example, by immersing the semiconductor substrate in a mixed solution of aqueous ammonia and hydrogen peroxide and treating at 60 ° C. to 80 ° C., organic substances and particles can be removed and cleaned. The cleaning time is preferably 10 seconds to 10 minutes, and more preferably 30 seconds to 5 minutes.

  There is no particular limitation on the method of forming the composition layer by applying the composition for forming a passivation layer of the present invention on a semiconductor substrate. For example, the method of providing the composition for forming a passivation layer of the present invention on a semiconductor substrate can be exemplified using a known coating method or the like. Specific examples include an immersion method, a screen printing method, an inkjet method, a dispenser method, a spin coating method, a brush coating method, a spray method, a doctor blade method, and a roll coating method. Among these, from the viewpoint of pattern formability and productivity, a screen printing method, an inkjet method, and the like are preferable.

  The application amount of the composition for forming a passivation layer of the present invention 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.

A passivation layer is formed on a semiconductor substrate by heat-treating (baking) the composition layer formed by the composition for forming a passivation layer to form a heat-treated material layer (fired material layer) derived from the composition layer. can do.
The heat treatment (firing) conditions of the composition layer are the niobium alkoxide contained in the composition layer, the organoaluminum compound and the specific metal alkoxide contained as necessary, the metal oxide or the heat treatment product (firing product) or There is no particular limitation as long as it can be converted into a complex oxide. In order to effectively give a fixed charge to the passivation layer and obtain a more excellent passivation effect, specifically, the heat treatment (firing) temperature is preferably 300 ° C to 900 ° C, more preferably 450 ° C 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 hours to 10 hours, and preferably 0.2 hours to 5 hours.

  In the method for producing a semiconductor substrate with a passivation layer of the present invention, the composition for forming a passivation layer is formed by applying the composition for forming a passivation layer of the present invention to a semiconductor substrate and before forming the passivation layer by heat treatment (firing). You may further have the process of drying the composition layer which consists of a thing. By including the step of drying the composition layer, a passivation layer having a more uniform passivation effect can be formed.

  If the step of drying the composition layer is capable of removing at least a part of water contained in the composition for forming a passivation layer and at least a part of a liquid medium that may be contained in the composition for forming a passivation layer. There is no particular restriction. The drying treatment can be, for example, a heat treatment at 30 ° C. to 250 ° C. for 1 minute to 60 minutes, and is preferably a heat treatment at 40 ° C. to 220 ° C. for 3 minutes to 40 minutes. The drying treatment may be performed under normal pressure or under reduced pressure.

  When the composition for forming a passivation layer contains a resin, the method for manufacturing a semiconductor substrate with a passivation layer according to the present invention provides the composition for forming a passivation layer, and then before the step of forming the passivation layer by heat treatment (firing). The composition layer comprising the composition for forming a passivation layer may further include a step of degreasing the composition layer. By having a step of degreasing the composition layer, a passivation layer having a more uniform passivation effect can be formed.

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

<Solar cell element>
The solar cell element of the present invention is provided with a semiconductor substrate having a pn junction part in which a p-type layer and an n-type layer are pn-junction, and at least part of at least one surface of the semiconductor substrate. A passivation layer, which is a heat-treated product of the layer forming composition, and an electrode disposed on at least one of the p-type layer and the n-type layer. The solar cell element of the present invention may further include other components as necessary.
The solar cell element of this invention is excellent in conversion efficiency by having the passivation layer formed from the composition for passivation layer formation of this invention.

  It does not restrict | limit especially as a semiconductor substrate which provides the composition for formation of the passivation layer of this invention, According to the objective, it can select suitably from what is normally used. As the semiconductor substrate, those described in the section of the semiconductor substrate with a passivation layer of the present invention can be used, and those that can be suitably used are also the same. It is preferable that the surface of the semiconductor substrate provided with the passivation layer of the present invention is the back surface of the solar cell element.

The thickness of the passivation layer formed on the semiconductor substrate is not particularly limited and can be appropriately selected according to the purpose. For example, the average thickness of the passivation layer is preferably 5 nm to 200 μm, more preferably 10 nm to 190 μm, and still more preferably 15 nm to 180 μm.
There is no restriction | limiting in the shape and magnitude | size of the solar cell element of this invention. For example, it is preferable that one side is a substantially square of 125 mm to 156 mm.

<Method for producing solar cell element>
The method for producing a solar cell element according to the present invention comprises the composition for forming a passivation layer according to the present invention on at least a part of at least one surface of a semiconductor substrate having a pn junction formed by pn junction of a p-type layer and an n-type layer. On the at least one of the p-type layer and the n-type layer, a step of applying a product to form a composition layer, a step of heat-treating (firing) the composition layer to form a passivation layer, Arranging the electrodes. The method for manufacturing a solar cell element of the present invention may further include other steps as necessary.

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

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

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

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

  In FIG. 1A, the p-type semiconductor substrate 1 is washed with an alkaline aqueous solution to remove organic substances, particles, and the like on the surface of the p-type semiconductor substrate 1. Thereby, the passivation effect improves more. As a cleaning method using an alkaline aqueous solution, a method using generally known RCA cleaning and the like can be mentioned.

  Thereafter, as shown in FIG. 1B, the surface of the p-type semiconductor substrate 1 is subjected to alkali etching or the like to form irregularities (also referred to as texture) on the surface. Thereby, reflection of sunlight can be suppressed on the light receiving surface side. For alkali etching, an etching solution composed of NaOH and IPA (i-propyl alcohol) can be used.

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

As a method for diffusing phosphorus, for example, a method of performing several tens of minutes at 800 ° C. to 1000 ° C. in a mixed gas atmosphere of phosphorus oxychloride (POCl ₃ ), nitrogen, and oxygen can be cited. In this method, since phosphorus is diffused using a mixed gas, the n ⁺ -type diffusion layer 2 is formed not only on the light receiving surface (front surface) but also on the back surface and side surfaces (not shown) as shown in FIG. Is formed. A PSG (phosphosilicate glass) layer 3 is formed on the n ⁺ -type diffusion layer 2. Therefore, side etching is performed to remove the side PSG layer 3 and the n ⁺ -type diffusion layer 2.

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

Then, as shown in FIG. 1 (6), an antireflection film 4 such as silicon nitride is formed on the n ⁺ -type diffusion layer 2 on the light-receiving surface by a PECVD (Plasma Enhanced Chemical Vapor Deposition) method or the like at a thickness of about 90 nm. Provide.

  Next, as shown in FIG. 1 (7), the passivation layer forming composition of the present invention is applied to a part of the back surface by screen printing or the like, and then dried (heated) at a temperature of 300 ° C. to 900 ° C. To form a passivation layer 5.

In FIG. 5, an example of the formation pattern of the passivation layer in the back surface is shown as a schematic plan view. FIG. 7 is an enlarged schematic plan view of a portion A in FIG. FIG. 8 is an enlarged schematic plan view of a portion B in FIG. In the case of the passivation layer formation pattern shown in FIG. 5, as can be seen from FIGS. 7 and 8, the back surface passivation layer 5 is formed in a dot shape except for the portion where the back surface output extraction electrode 7 is formed in a later step. The pattern semiconductor substrate 1 is formed with an exposed pattern. The pattern of the dot-shaped openings is defined by the dot diameter (L _a ) and the dot interval (L _b ), and is preferably arranged regularly. Dot diameter _{(L a)} and the dot interval _{(L b)} is can be arbitrarily set, in view of suppressing the recombination of the passivation effect and minority carriers, that _{L a} is _{L b} in 5μm~2mm is 10μm~3mm It is more preferable that L _a is 10 μm to 1.5 mm and L _b is 20 μm to 2.5 mm, and it is more preferable that L _a is 20 μm to 1.3 mm and L _b is 30 μm to 2 mm.

In the case where the composition for forming a passivation layer has an excellent pattern forming property, the dot diameter (L _a ) and the dot interval (L _b ) are more regularly arranged in this dot-like opening pattern. For this reason, a preferable dot-shaped opening pattern can be formed by suppressing minority carrier recombination, and the power generation efficiency of the solar cell element is improved.

  Here, a passivation layer having a desired shape is formed by applying the passivation layer forming composition to a portion where the passivation layer is to be formed (portion other than the dot-shaped opening) and heat-treating (sintering). . On the other hand, the passivation layer forming composition can be applied to the entire surface including the dot-shaped opening, and the passivation layer in the dot-shaped opening can be selectively removed by laser, photolithography, etc. after heat treatment (firing). . Alternatively, the passivation layer forming composition can be selectively applied by previously masking a portion such as a dot-shaped opening where the passivation layer forming composition is not desired to be applied with a mask material.

  Next, as shown in FIG. 1 (8), a silver electrode paste containing glass particles is applied to the light receiving surface by screen printing or the like. FIG. 4 is a schematic plan view showing an example of the light receiving surface of the solar cell element. As shown in FIG. 4, the light receiving surface electrode includes a light receiving surface current collecting electrode 8 and a light receiving surface output extraction electrode 9. In order to secure a light receiving area, it is necessary to suppress the formation area of these light receiving surface electrodes. In addition, from the viewpoint of the resistivity and productivity of the light receiving surface electrode, the width of the light receiving surface current collecting electrode 8 is preferably 10 μm to 250 μm, and the width of the light receiving surface output extraction electrode 9 is preferably 100 μm to 2 mm. In FIG. 4, two light receiving surface output extraction electrodes 9 are provided. However, from the viewpoint of minority carrier extraction efficiency (power generation efficiency), the number of light receiving surface output extraction electrodes 9 may be three or four. it can.

  On the other hand, as shown in FIG. 1 (8), an aluminum electrode paste containing glass powder and a silver electrode paste containing glass particles are applied to the back surface by screen printing or the like. FIG. 9 is a schematic plan view showing an example of the back surface of the solar cell element. Although the width | variety of the back surface output extraction electrode 7 is not restrict | limited in particular, From viewpoints, such as connectivity of the wiring material in the manufacturing process of a later solar cell, it is preferable that the width | variety of the back surface output extraction electrode 7 is 100 micrometers-10 mm.

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

After heat treatment (firing), as shown in FIG. 1 (9), on the light receiving surface, the glass particles contained in the silver electrode paste forming the light receiving surface electrode react with the antireflection film 4 (fire through), The light-receiving surface electrode (light-receiving surface current collecting electrode 8, light-receiving surface output extraction electrode 9) and the n ⁺ -type diffusion layer 2 are electrically connected (ohmic contact). On the other hand, on the back surface, in the portion where the semiconductor substrate 1 is exposed in the form of dots (the portion where the passivation layer 5 is not formed), the aluminum in the aluminum electrode paste diffuses into the semiconductor substrate 1 by heat treatment (firing). , P ⁺ -type diffusion layer 10 is formed. In the present invention, by using the composition for forming a passivation layer of the present invention having excellent pattern formability, a passivation layer having excellent passivation effect can be formed by a simple method, and a solar cell element having excellent power generation performance is produced. be able to.

FIG. 2 is a cross-sectional view showing another example of a method for manufacturing a solar cell element having a passivation layer according to this embodiment, and the n ⁺ -type diffusion layer 2 on the back surface is removed by an etching process. After that, the solar cell element can be manufactured in the same manner as in FIG. 1 except that the back surface is further flattened. When flattening, a technique such as immersing the back surface of the semiconductor substrate in a mixed solution of nitric acid, hydrofluoric acid and acetic acid or a potassium hydroxide solution can be used.

FIG. 3 is a cross-sectional view showing a process diagram illustrating another example of a method for manufacturing a solar cell element having a passivation layer according to the present embodiment. This method is the same as the method shown in FIG. 1 until the step of forming the texture structure, the n ⁺ -type diffusion layer 2 and the antireflection film 4 on the semiconductor substrate 1 (FIGS. 3 (19) to (24)).

  After forming the antireflection film 4, as shown in FIG. 3 (25), a composition for forming a passivation layer is applied. In FIG. 6, an example of the formation pattern of the passivation layer in the back surface is shown as a schematic plan view. In the formation pattern of the passivation layer shown in FIG. 6, dot-like openings are arranged on the entire back surface, and dot-like openings are also arranged on the portion where the back-surface output extraction electrode is formed in a later step.

Thereafter, as shown in FIG. 3 (26), from the portion where the semiconductor substrate 1 in a dot shape is exposed (the portion passivation layer 5 is not formed) on the rear surface, to diffuse boron or aluminum, p ⁺ -type diffusion layer 10 Form. When boron is diffused when forming the p ⁺ -type diffusion layer 10, a method of treating at a temperature around 1000 ° C. in a gas containing boron trichloride (BCl ₃ ) can be used. However, since the method of gas diffusion is the same as in the case of using phosphorus oxychloride, the p ⁺ -type diffusion layer 10 is formed on the light receiving surface, the back surface, and the side surface of the substrate. It is necessary to take measures such as masking the portions other than the openings to prevent boron from diffusing into unnecessary portions of the p-type semiconductor substrate 1.

In addition, when aluminum is diffused when forming the p ⁺ -type diffusion layer 10, the aluminum paste is applied to the dot-shaped opening, and this is heat-treated (fired) at a temperature of 450 ° C. to 900 ° C. It is possible to use a technique in which aluminum is diffused from the opening to form the p ⁺ -type diffusion layer 10 and then a heat treatment product layer (baked product layer) made of an aluminum paste on the p ⁺ -type diffusion layer 10 is etched with hydrochloric acid or the like. it can.

  Next, as shown in FIG. 3 (27), aluminum is physically vapor-deposited on the entire back surface to form the back surface collecting aluminum electrode 11.

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

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

<Solar cell>
The solar cell of the present invention includes at least one of the solar cell elements of the present invention, and is configured by arranging a wiring material on the electrode of the solar cell element. That is, the solar cell of this invention has the said solar cell element and the wiring material arrange | positioned on the said electrode of the said solar cell element.
If necessary, the solar cell of the present invention is constituted by connecting a plurality of 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 technical field.

  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.

(Preparation of composition 1 for forming a passivation layer)
3.663 g of pentaethoxyniobium (Hokuko Chemical Co., Ltd., structural formula: Nb (OC ₂ H ₅ ) ₅ , molecular weight: 318.2), aluminum ethyl acetoacetate di-i-propylate (Kawaken Fine Chemical Co., Ltd.) Name: ALCH) 3.667 g, terpineol (Nippon Terpene Chemical Co., Ltd., sometimes abbreviated as TPO) 11.107 g, isobornylcyclohexanol (Nippon Terpene Chemical Co., Ltd., sometimes abbreviated as tersolve) Was mixed and kneaded for 5 minutes, and then 1.350 g of pure water was added and further kneaded for 5 minutes to prepare a composition 1 for forming a passivation layer.

(Evaluation of thixotropy)
The shear viscosity of the composition 1 for forming a passivation layer prepared above was attached to a rotary shear viscometer (AntonPaar, MCR301) with a cone plate (diameter 50 mm, cone angle 1 °) at a temperature of 25 ° C. Measurements were made under conditions of speeds of 0.1 s ⁻¹ and 10.0 s ⁻¹ , respectively.
The shear viscosity (η ₁ ) at a shear rate of 0.1 s ⁻¹ was 4930 Pa · s, and the shear viscosity (η ₂ ) at a shear rate of 10.0 s ⁻¹ was 55 Pa · s. The thixo ratio (η ₁ / η ₂ ) when the shear rate was 0.1 s ⁻¹ and 10.0 s ⁻¹ was 89.6.

(Evaluation of pattern formability)
For the evaluation of the pattern formability of the composition for forming a passivation layer, a single crystal p-type silicon substrate (50 mm square, thickness 160 μm, hereinafter referred to as silicon substrate B) having a facet shape was used as a semiconductor substrate. The silicon substrate B is a single crystal p-type silicon substrate (thickness 180 μm) with a textured surface, and 30% NaOH at 80 ° C. using an automatic substrate cleaning machine (Samasu Semiconductor Industry Co., Ltd., PV-MECH1 type). After washing for 10 minutes to make the surface faceted, it was washed with pure water for 10 minutes and dried with warm air.

  The prepared composition 1 for forming a passivation layer was printed on the entire surface of the silicon substrate B other than the openings of the dot-like or line-like pattern using a screen printing method. Screen printing was performed using a screen printing machine (Neurong Seimitsu Kogyo Co., Ltd., LZ-0913).

The dot-shaped opening pattern used for the evaluation has a dot diameter (L _a ) of 200 μm and a dot interval (L _b ) of 0.886 mm, a dot diameter (L _a ) of 150 μm and a dot interval (L _b ) of Three types of patterns were prepared: a 0.664 mm pattern and a dot diameter (L _a ) of 100 μm and a dot interval (L _b ) of 0.443 mm. Further, the pattern of the line-shaped openings used for the evaluation is a pattern having a line width (L _a ) of 200 μm and a line interval (L _b ) of 1.0 mm, and a line width (L _a ) of 150 μm and a line interval (L _b). ) Is a 1.0 mm pattern, and three patterns are prepared: _a line width (L _a ) of 100 μm and a line interval (L _b ) of 1.0 mm.

  The silicon substrate B to which the composition 1 for forming a passivation layer was applied by screen printing was heated at 150 ° C. for 5 minutes, and the liquid medium was evaporated to dry the silicon substrate B. Next, the silicon substrate B was heat-treated (fired) at a temperature of 700 ° C. for 10 minutes, and then allowed to cool at room temperature (25 ° C.). The heat treatment (firing) was performed using a diffusion furnace (ACCURON CQ-1200, Hitachi Kokusai Electric Inc.) under conditions of a maximum temperature of 700 ° C. and a holding time of 10 minutes in an air atmosphere.

In the evaluation of pattern formability, the dot diameter (L _a ) of the dot-shaped opening in the passivation layer formed on the substrate after heat treatment (firing) was measured. At that time, the dot diameter (L _a ) was measured at 10 points, and the average value was calculated.
Here, with respect to the dot diameter (L _a ) immediately after printing, the change rate of the dot diameter (L _a ) after the heat treatment (firing) is less than 15%, and the change rate of 15% or more and less than 30% is Δ, Those with 30% or more were evaluated as x. If evaluation is (circle) or (triangle | delta), the pattern formation property of the composition for passivation layer formation is favorable.

(Measurement of effective lifetime)
For the measurement of effective lifetime, a single crystal p-type silicon substrate (50 mm square, thickness 770 μm, hereinafter referred to as silicon substrate A) having a mirror shape was used. The prepared composition 1 for forming a passivation layer was printed on the entire surface of the silicon substrate A using a screen printing method. Thereafter, the silicon substrate A provided with the passivation layer forming composition 1 was heated at 150 ° C. for 5 minutes to dry the liquid medium by evaporating. Thereafter, the passivation layer forming composition 1 was printed on the other surface of the silicon substrate A, followed by drying treatment. Next, the silicon substrate A was heat-treated (baked) for 10 minutes at a temperature of 700 ° C. and then allowed to cool at room temperature (25 ° C.). The heat treatment (firing) was performed using a diffusion furnace (ACCURON CQ-1200, Hitachi Kokusai Electric) under the conditions of an atmospheric temperature and a maximum temperature of 700 ° C. and a holding time of 10 minutes.

  The effective lifetime of the substrate for evaluation obtained above was measured by a reflected microwave photoconductive decay method at room temperature (25 ° C.) using a lifetime measurement device (Nippon Semi-Lab Co., Ltd., WT-2000PVN). In the obtained evaluation substrate, the effective lifetime of the region to which the passivation layer forming composition was applied was 1004 μs.

<Example 2>
In Example 1, the compounding amount of the components of the composition for forming a passivation layer was changed. Specifically, the content of each component was changed to 3.778 g of pentaethoxyniobium (Hokuko Chemical Co., Ltd., structural formula: Nb (OC ₂ H ₅ ) ₅ , molecular weight: 318.2), and 8.944 g of terpineol. In the same manner as in Example 1, except that 32.427 g of isobornylcyclohexanol, 3.781 g of aluminum ethylacetoacetate di-i-propylate, and 1.392 g of pure water were changed. Composition 2 was prepared.
Thereafter, in the same manner as in Example 1, evaluation of the thixotropy, evaluation of pattern formation, and evaluation of effective lifetime of the composition 2 for forming a passivation layer were performed.

<Example 3>
In Example 1, the compounding amount of the components of the composition for forming a passivation layer was changed. Specifically, the content of each component is 2.518 g of pentaethoxyniobium (Hokuko Chemical Co., Ltd., structural formula: Nb (OC ₂ H ₅ ) ₅ , molecular weight: 318.2), and 12.278 g of terpineol. In the same manner as in Example 1 except that 31.986 g of isobornylcyclohexanol, 2.519 g of aluminum ethyl acetoacetate di-i-propylate and 0.928 g of pure water were changed. Composition 3 was prepared.
Thereafter, in the same manner as in Example 1, evaluation of the thixotropy, evaluation of pattern formation, and evaluation of effective lifetime of the composition 3 for forming a passivation layer were performed.

<Example 4>
In Example 1, the compounding amount of the components of the composition for forming a passivation layer was changed. Specifically, the content of each component was 2.518 g of pentaethoxyniobium (Hokuko Chemical Co., Ltd., structural formula: Nb (OC ₂ H ₅ ) ₅ , molecular weight: 318.2), and 9.7742 g of terpineol. In the same manner as in Example 1, except that 34.12 g of isobornylcyclohexanol, 2.5202 g of aluminum ethylacetoacetate di-i-propylate, and 0.928 g of pure water were changed. Composition 4 was prepared.
Thereafter, in the same manner as in Example 1, evaluation of the thixotropy of the composition 4 for forming a passivation layer, evaluation of pattern formation, and evaluation of effective lifetime were performed.

<Reference Example 1>
In the preparation of the composition for forming a passivation layer in Example 1, pentaethoxyniobium was not used as a component of the composition for forming a passivation layer. Specifically, the content of each component was changed to 6.419 g of terpineol, 17.217 g of isobornylcyclohexanol, 3.268 g of aluminum ethyl acetoacetate di-i-propylate, and 1.495 of pure water. A composition R1 for forming a passivation layer was prepared in the same manner as in Example 1 except that.
Thereafter, in the same manner as in Example 1, evaluation of the thixotropy of the composition R1 for forming a passivation layer, evaluation of pattern formation, and evaluation of effective lifetime were performed.

<Reference Example 2>
In the preparation of the passivation layer forming composition in Example 2, pure water was not used. Specifically, the content of each component was 2.928 g of pentaethoxyniobium (Hokuko Chemical Co., Ltd., structural formula: Nb (OC ₂ H ₅ ) ₅ , molecular weight: 318.2), and 6.489 g of terpineol. A composition R2 for forming a passivation layer was prepared in the same manner as in Example 1 except that 17.535 g of isobornylcyclohexanol and 2.950 g of aluminum ethylacetoacetate di-i-propylate were changed.
Thereafter, in the same manner as in Example 1, evaluation of the thixotropy, pattern formation, and effective lifetime of the passivation layer forming composition R2 were performed.

<Comparative Example 1>
In the preparation of the composition for forming a passivation layer in Example 1, pentaethoxyniobium and aluminum ethyl acetoacetate di-i-propylate were not used. Specifically, passivation was performed in the same manner as in Example 1 except that the content of each component was changed to 6.015 g of terpineol, 16.815 g of isobornylcyclohexanol, and 1.423 g of pure water. A layer forming composition C1 was prepared.
Thereafter, in the same manner as in Example 1, evaluation of the thixotropy, pattern formation, and effective lifetime of the passivation layer forming composition C1 were performed.

  Table 1 shows the composition of the composition for forming a passivation layer prepared in Examples 1 to 4, Reference Examples 1 to 2, and Comparative Example 1. Table 2 shows the evaluation results of the thixo ratio, pattern formability, and lifetime of the compositions for forming a passivation layer implemented in Examples 1 to 4, Reference Examples 1 to 2, and Comparative Example 1.

  It was found that the passivation layer forming compositions prepared in Examples 1 to 4 have good thixo ratio and pattern formability.

  Moreover, the effective lifetime evaluated in Examples 1 to 4 greatly exceeded that measured in Comparative Example 1. Thereby, it was found that an excellent passivation layer derived from niobium alkoxide was formed by using the composition for forming a passivation layer of the present invention.

  The thixo ratio of the composition for forming a passivation layer tended to be relatively high when a composition containing niobium alkoxide and water was used as the composition for forming a passivation layer. This is an effect obtained by including niobium alkoxide and water in the composition for forming a passivation layer, as described above.

  Furthermore, when the composition for forming a passivation layer containing both niobium alkoxide and organoaluminum compound was used, the effective lifetime tended to be relatively high. About this, by including both the niobium alkoxide and the organoaluminum compound in the composition for forming the passivation layer, a complex oxide of niobium alkoxide-derived metal (niobium) and aluminum is formed by heat treatment (firing), so that the denser This is probably because the passivation effect is further improved by forming a passivation layer having a large negative fixed charge.

  It turned out that the effective lifetime of the silicon substrate A produced by the comparative example 1 is low compared with the reference examples 1 and 2 and Examples 1-6. This is probably because the passivation layer forming composition C1 does not contain niobium alkoxide, and a sufficient passivation effect was not obtained from the passivation layer formed by heat treatment (firing). .

1: p-type semiconductor substrate, 2: n ⁺ -type diffusion layer, 3: PSG (phosphorus silicate glass) layer, 4: antireflection film, 5: passivation layer, 6: aluminum electrode paste, or heat-treated (fired) Back surface collecting aluminum electrode, 7: Back surface output extraction electrode paste, or back surface output extraction electrode obtained by heat treatment (baking), 8: Light receiving surface current collection electrode paste, or light receiving surface current collection obtained by heat treatment (firing) Electrode: 9: light receiving surface output extraction electrode paste, or light receiving surface output extraction electrode obtained by heat treatment (baking), 10: p ⁺ type diffusion layer, 11: aluminum electrode for backside current collection, 12: solar cell element, 13 : Wiring member, 14: Sealing material, 15: Back sheet, 16: Glass plate.

Claims (9)

A composition for forming a passivation layer, comprising a compound represented by the following general formula (I) and water.
Nb (OR ¹ ) ₅ (I)
[In General Formula (I), each R ¹ independently represents an alkyl group or an aryl group. ] A composition for forming a passivation layer, comprising a hydrolyzate of a compound represented by the following general formula (I).
Nb (OR ¹ ) ₅ (I)
[In General Formula (I), each R ¹ independently represents an alkyl group or an aryl group. ] The composition for forming a passivation layer according to claim ¹ , wherein at least one of R ^{1 in} the compound represented by the general formula (I) is an ethyl group. Furthermore, the composition for formation of a passivation layer of any one of Claims 1-3 containing the compound represented with the following general formula (II).

[In General Formula (II), each R ² independently represents an alkyl group. n represents an integer of 1 to 3. X ² and X ³ each independently represent an oxygen atom or a methylene group. R ³ , R ⁴ and R ⁵ each independently represents a hydrogen atom or an alkyl group. ] A semiconductor substrate;
A passivation layer, which is a heat treatment product of the composition for forming a passivation layer according to any one of claims 1 to 4, provided on at least a part of at least one surface of the semiconductor substrate,
A semiconductor substrate with a passivation layer. A step of providing a composition for forming a passivation layer according to any one of claims 1 to 4 on at least a part of at least one surface of a semiconductor substrate to form a composition layer;
Heat-treating the composition layer to form a passivation layer;
The manufacturing method of the semiconductor substrate with a passivation layer which has this. a semiconductor substrate having a pn junction formed by p-type junction of a p-type layer and an n-type layer;
A passivation layer, which is a heat treatment product of the composition for forming a passivation layer according to any one of claims 1 to 4, provided on at least a part of at least one surface of the semiconductor substrate,
An electrode disposed on at least one of the p-type layer and the n-type layer;
A solar cell element having 5. The passivation layer forming device according to claim 1, wherein at least a part of at least one surface of a semiconductor substrate having a pn junction formed by pn junction of a p-type layer and an n-type layer is formed. Applying the composition to form a composition layer;
Heat-treating the composition layer to form a passivation layer;
Disposing an electrode on at least one of the p-type layer and the n-type layer;
The manufacturing method of the solar cell element which has this. The solar cell element according to claim 7,
A wiring material disposed on the electrode of the solar cell element;
A solar cell having: