TWI485875B - Composition for forming impurity diffusion layer, composition for forming n-type diffusion layer, method for forming n-type diffusion layer, composition for forming p-type diffusion layer, method for forming p-type diffusion layer, and method for produci - Google Patents

Description

Composition for forming impurity diffusion layer, composition for forming n-type diffusion layer, method for producing n-type diffusion layer, composition for forming p-type diffusion layer, method for producing p-type diffusion layer, and method for producing solar cell

The present invention relates to a composition for forming an n-type diffusion layer of a solar cell, a method for producing an n-type diffusion layer, a composition for forming a p-type diffusion layer, a method for producing a p-type diffusion layer, and a method for producing a solar cell. More specifically, the present invention relates to a technique capable of forming an n-type diffusion layer at a specific portion of a germanium substrate as a semiconductor substrate, and a technique for forming a p-type diffusion layer capable of reducing a germanium substrate as a semiconductor substrate Internal stress, suppression of damage to the crystal grain boundary, suppression of increase in crystal defects, and suppression of warpage.

The conventional process of solar cell elements is described below.

First, by promoting an optical confinement effect to achieve high efficiency, a p-type germanium substrate having a texture structure formed on a light-receiving surface is modulated, and then the p-type germanium substrate is in the compound containing the donor element. The phosphorus oxychloride (POCl ₃ ), a mixed gas of nitrogen and oxygen are subjected to a treatment at 800 ° C to 900 ° C for several tens of minutes to uniformly form an n-type diffusion layer on the substrate. According to the method of the prior art, since the diffusion of phosphorus is performed using the mixed gas, not only the n-type diffusion layer is formed on the surface but also the n-type diffusion layer is formed on the side surface and the back surface. For these reasons, side etching is required to remove the side n-type diffusion layer. In addition, it is necessary to convert the n-type diffusion layer on the back surface into a p ⁺ -type diffusion layer, and apply an aluminum paste on the n-type diffusion layer on the back surface and sinter it to convert the n-type diffusion layer into p ⁺ by diffusion of aluminum. Type diffusion layer.

On the other hand, in the field of semiconductor manufacturing, for example, as a compound containing a donor element, a coating containing, for example, phosphorus pentoxide (P ₂ O ₅ ) is proposed as disclosed in Japanese Laid-Open Patent Publication No. 2002-75894. A method of forming an n-type diffusion layer by a phosphate solution such as ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ). However, since the donor element or the compound containing the donor element is scattered from the solution of the diffusion source in this method, the diffusion of phosphorus also reaches the side when the diffusion layer is formed, as in the gas phase reaction method using the mixed gas described above. On the back side, an n-type diffusion layer is also formed in a portion other than the coating.

Further, in the method of imparting the above-described aluminum paste to convert the n-type diffusion layer into the p ⁺ -type diffusion layer, the aluminum layer formed of the aluminum paste has a low electrical conductivity, and is usually formed in order to lower sheet resistance. The aluminum layer on the entire back surface must have a thickness of about 10 μm to 20 μm after calcination (sintering). Furthermore, if an aluminum layer as thick as described above is formed, since the coefficient of thermal expansion of the crucible differs greatly from the coefficient of thermal expansion of aluminum, large internal stress is generated in the crucible substrate during sintering and cooling, and there is a grain boundary. Damage, increased crystal defects, and warpage.

In order to solve this problem, there is a method of reducing the amount of coating of the aluminum paste and thinning the back electrode layer. However, when the coating amount of the aluminum paste is reduced, the amount of aluminum diffused from the surface of the p-type germanium semiconductor substrate to the inside becomes insufficient. As a result, the desired back surface field (BSF) effect cannot be achieved (the collection efficiency of the generated carrier is improved by the presence of the p ⁺ -type diffusion layer), and thus solar energy is generated. The problem of degraded battery characteristics.

Thus, for example, Japanese Laid-Open Patent Publication No. 2003-223813 proposes a paste composition comprising aluminum powder, an organic vehicle, and a coefficient of thermal expansion smaller than aluminum and having a melting temperature, a softening temperature, and a decomposition temperature. Any of the inorganic compound powders having a higher melting point than aluminum.

As described above, in the gas phase reaction using phosphorus oxychloride in forming the n-type diffusion layer, the n-type diffusion layer is formed not only on one side (usually the light-receiving side or the surface) of the necessary n-type diffusion layer, but also It is even formed on other faces (non-light-receiving side, or rear surface) or on the side. Further, in the method of applying a solution containing a phosphate and performing thermal diffusion, it is also the same as the gas phase reaction method, and an n-type diffusion layer is formed even outside the surface. Therefore, in order to obtain a pn junction structure as an element, it is necessary to perform etching on the side, and it is necessary to convert the n-type diffusion layer into a p-type diffusion layer on the back side. In general, a paste of aluminum as a Group 13 element (Group IIIA) is applied to the back surface, and calcination (sintering) is performed to convert the n-type diffusion layer into a p-type diffusion layer.

The present invention has been made in view of the above problems, and an object of the invention is to provide an n-type diffusion layer that can be formed on a specific portion for a short period of time without causing unnecessary formation in a method for manufacturing a solar cell element using a germanium substrate. A composition for forming an n-type diffusion layer, a method for producing an n-type diffusion layer, and a method for producing a solar cell.

In addition, even if the paste composition converted from the n-type diffusion layer into the p ⁺ -type diffusion layer described in the above-mentioned Japanese Patent Publication No. 2003-223813 is used, the warpage may not be sufficiently suppressed. Therefore, an object of the present invention is to provide a composition for forming a p-type diffusion layer which can suppress the internal stress in the ruthenium substrate and suppress the occurrence of warpage of the substrate while forming a p-type diffusion layer in a short time. A method of producing a p-type diffusion layer and a method of producing a solar cell element.

The above problems are solved by the following means.

<1> A composition for forming an impurity diffusion layer, comprising: a glass powder containing a donor element or an acceptor element, and a dispersion medium, wherein a content ratio of the glass powder is 1% by mass or more It is in the range of 90% by mass or less.

<2> A composition for forming an n-type diffusion layer, comprising: a glass powder containing a donor element, and a dispersion medium, wherein a content ratio of the glass powder is in a range of from 1% by mass or more to 90% by mass or less .

<3> The composition for forming an n-type diffusion layer according to the above <2>, wherein the donor element is at least one selected from the group consisting of P (phosphorus) and Sb (antimony).

<4> The composition for forming an n-type diffusion layer according to the above <2> or <3>, wherein the glass powder containing the donor element includes a substance containing a donor element and a glass component substance, and the above-mentioned donor body The substance of the element is at least one selected from the group consisting of P ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ , and the glass component is selected from the group consisting of SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO. At least one of MgO, BeO, ZnO, PbO, CdO, SnO, ZrO ₂ and MoO ₃ .

The composition for forming an n-type diffusion layer according to any one of <2> to <4> above, further comprising selected from the group consisting of Ag, Cu, Fe, Zn, and Mn. At least one metal, Si, or a combination thereof.

<6> The composition for forming an n-type diffusion layer according to the above <5>, wherein the metal is Ag (silver).

<7> A method of producing an n-type diffusion layer, comprising: a step of applying a composition for forming an n-type diffusion layer according to any one of the above <2> to <6> on a semiconductor substrate; The step of thermal diffusion treatment.

(8) A method of producing a solar cell element, comprising: a step of applying a composition for forming an n-type diffusion layer according to any one of the above <2> to <6> on a semiconductor substrate; and performing thermal diffusion a step of forming an n-type diffusion layer; and forming an electrode on the formed n-type diffusion layer.

<9> A composition for forming a p-type diffusion layer, comprising: a glass powder containing an acceptor element; and a dispersion medium, wherein a content ratio of the glass powder is in a range of from 1% by mass to 90% by mass.

<10> The composition for forming a p-type diffusion layer according to the above <9>, wherein the acceptor element is at least one selected from the group consisting of B (boron), Al (aluminum), and Ga (gallium).

<11> The composition for forming a p-type diffusion layer according to the above <9> or <10>, wherein the glass powder containing the acceptor element includes a substance containing an acceptor element and a glass component substance, and the above-mentioned acceptor The substance of the element is at least one selected from the group consisting of B ₂ O ₃ , Al ₂ O ₃ and Ga ₂ O ₃ , and the glass component is selected from the group consisting of SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO. At least one of MgO, BeO, ZnO, PbO, CdO, Tl ₂ O, SnO, ZrO ₂ and MoO ₃ .

<12> A method of producing a p-type diffusion layer, comprising: a step of applying a composition for forming a p-type diffusion layer according to any one of the above <9> to <11> on a semiconductor substrate; The step of thermal diffusion treatment.

<13> A method of producing a solar cell element, comprising: a step of applying a composition for forming a p-type diffusion layer according to any one of the above <9> to <11> on a semiconductor substrate; performing thermal diffusion a step of forming a p-type diffusion layer; and forming an electrode on the formed p-type diffusion layer.

According to the present invention, in the method of manufacturing a solar cell using a tantalum substrate, an n-type diffusion layer can be formed on a specific region in a short time without forming an unnecessary n-type diffusion layer.

Further, according to the present invention, it is possible to form a p-type diffusion layer in a short time while suppressing internal stress in the ruthenium substrate and suppressing occurrence of warpage of the substrate in the method of manufacturing a solar cell using the ruthenium substrate.

The present invention is a composition for forming an impurity diffusion layer, comprising: a glass powder containing a donor element or an acceptor element, and a dispersion medium, wherein a content ratio of the glass powder is in a range of from 1% by mass to 90% by mass. When the composition forming the impurity diffusion layer is a composition forming an n-type diffusion layer, the glass powder includes a donor element, and when the composition forming the impurity diffusion layer is a composition forming a p-type diffusion layer, the glass powder includes Receptor element.

The content of the glass powder contained in the composition forming the n-type diffusion layer and the composition forming the p-type diffusion layer is 1% by mass or more and 90% by mass or more In the following range, the glass layer formed on the n-type diffusion layer or the p-type diffusion layer can be removed in a short time. Further, the formation of the n-type diffusion layer or the formation of the p-type diffusion layer is sufficiently performed by diffusion of the donor element or the acceptor element. Therefore, according to the composition for forming an n-type diffusion layer of the present invention and the formation of the p-type diffusion layer, the n-type diffusion layer or the p-type diffusion layer can be formed in a specific portion for a short time.

First, the composition for forming an n-type diffusion layer and the composition for forming a p-type diffusion layer of the present invention will be described. Next, a method for producing an n-type diffusion layer using a composition for forming an n-type diffusion layer, and a method for forming a p-type diffusion will be described. A method for producing a p-type diffusion layer of a composition of a layer and a method for producing a solar cell element will be described.

Furthermore, in the present specification, the term "process" means not only an independent step but also a case where it cannot be clearly distinguished from other steps, and if the step can achieve the intended effect, then Also included in this term. In addition, in the present specification, when "~" is used to indicate the range of numerical values, "~" indicates a range including the numerical values described before and after the minimum value and the maximum value.

<Formation of n-type diffusion layer>

The composition for forming an n-type diffusion layer of the present invention includes a glass powder containing at least a donor element (hereinafter sometimes referred to simply as "glass powder") and a dispersion medium, and further, in consideration of coatability and the like, if necessary, it may be optionally contained. Other additives.

Here, the composition for forming an n-type diffusion layer is a glass powder containing a donor element, and can be applied to a ruthenium substrate, The donor element is thermally diffused to form a material of the n-type diffusion layer. By using the composition for forming an n-type diffusion layer of the present invention, an n-type diffusion layer is formed only at a desired portion, and an unnecessary n-type diffusion layer is not formed on the back surface or the side surface.

Therefore, if the composition for forming an n-type diffusion layer of the present invention is applied, the side etching step necessary in the gas phase reaction method which has been widely used previously becomes unnecessary, thereby simplifying the steps. Further, the step of converting the n-type diffusion layer formed on the back surface into a p ⁺ -type diffusion layer also becomes unnecessary. Therefore, the method of forming the p ⁺ -type diffusion layer on the back surface, or the material, shape, and thickness of the back surface electrode is not limited, and the applicable manufacturing method, material, and shape selection are expanded. Further, since the occurrence of internal stress in the ruthenium substrate due to the thickness of the back surface electrode is suppressed, warpage of the ruthenium substrate is also suppressed, and details will be described later.

Further, the glass powder contained in the composition for forming the n-type diffusion layer of the present invention is melted by calcination to form a glass layer on the n-type diffusion layer. However, in the prior gas phase reaction method or the method of coating a solution containing a phosphate, a glass layer is also formed on the n-type diffusion layer. Therefore, the glass layer produced in the present invention can be removed by etching as in the prior method. Therefore, the composition for forming an n-type diffusion layer of the present invention does not produce an unnecessary product, and does not add a step, even if compared with the prior method.

When the content of the glass powder contained in the composition forming the n-type diffusion layer is in the range of 1% by mass or more to 90% by mass or less, the glass layer formed on the n-type diffusion layer can be removed in a short time. . Further, the formation of the n-type diffusion layer is sufficiently performed by diffusion of the donor element.

Furthermore, the time required for "forming an n-type diffusion layer" in the present invention means: for forming an n-type diffusion layer plus for removing a glass layer formed on the n-type diffusion layer. Total time. According to this, the time for forming the n-type diffusion layer is shortened by removing the glass layer formed on the n-type diffusion layer in a short time.

Further, since the donor component in the glass powder is hardly sublimated in the calcination, it is suppressed that the n-type diffusion layer is formed not only on the surface but also on the back surface or the side surface due to the generation of the volatilized gas. The reason for this is considered to be that it is difficult to volatilize because the donor component is combined with an element in the glass powder or introduced into the glass.

As described above, the composition for forming an n-type diffusion layer of the present invention can form an n-type diffusion layer having a desired concentration at a desired portion, and thus can form a selective region having a high n-type dopant concentration. On the other hand, it is generally difficult to form a selective region of a high n-type dopant concentration by a gas reaction method using a general method of an n-type diffusion layer or a solution containing a phosphate.

The glass powder containing the donor element of the present invention will be described in detail.

The donor element refers to an element which can form an n-type diffusion layer by doping it in a germanium substrate. As the donor element, an element of Group 15 of the periodic table can be used, and examples thereof include P (phosphorus), Sb (antimony), Bi (antimony), and As (arsenic). From the viewpoints of safety, ease of vitrification, and the like, P or Sb is more preferable.

Examples of the substance containing a donor element for introducing a donor element into the glass powder include P ₂ O ₃ , P ₂ O ₅ , Sb ₂ O ₃ , Bi ₂ O ₃ and As ₂ O ₃ , preferably At least one selected from the group consisting of P ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ is used.

Further, the glass powder containing the donor element may be adjusted in composition ratio as needed, thereby controlling the melting temperature, the softening temperature, the glass transition temperature, the chemical durability, and the like. It is preferable to further include the glass component substance described below.

Examples of the glass component material include SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO ₂ , MoO ₃ , and La ₂ O. ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , Y ₂ O ₃ , TiO ₂ , ZrO ₂ , GeO ₂ , TeO ₂ and Lu ₂ O _{3 ,} etc., preferably selected from SiO ₂ , K ₂ O, Na ₂ At least one of O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO ₂ and MoO ₃ .

Specific examples of the glass powder containing the donor element include a system containing both the donor element and the glass component, and examples thereof include a P ₂ O ₅ —SiO ₂ system (containing a donor element). The order of the substance-glass component substance is the same as the following), P ₂ O ₅ -K ₂ O system, P ₂ O ₅ -Na ₂ O system, P ₂ O ₅ -Li ₂ O system, P ₂ O ₅ -BaO system , P ₂ O ₅ -SrO system, P ₂ O ₅ -CaO system, P ₂ O ₅ -MgO system, P ₂ O ₅ -BeO system, P ₂ O ₅ -ZnO system, P ₂ O ₅ -CdO system, P ₂ O ₅ -PbO system, P ₂ O ₅ -V ₂ O ₅ system, P ₂ O ₅ -SnO system, P ₂ O ₅ -GeO ₂ system, P ₂ O ₅ -TeO ₂ system, etc. include P ₂ O ₅ as A system containing a substance of a donor element, and a glass powder comprising a system in which P ₂ O ₅ of the above-described system including P ₂ O ₅ is replaced by Sb ₂ O ₃ as a substance containing a donor element.

Further, it may be a glass powder containing two or more kinds of substances containing a donor element, such as a P ₂ O ₅ -Sb ₂ O ₃ system or a P ₂ O ₅ -As ₂ O ₃ system.

Although the composite glass including the two components is exemplified above, it may be a glass powder including a substance of three or more components such as P ₂ O ₅ —SiO ₂ —V ₂ O ₅ , P ₂ O ₅ —SiO ₂ —CaO. .

The content ratio of the glass component in the glass powder is preferably set in consideration of the melting temperature, the softening temperature, the glass transition temperature, and the chemical durability, and is generally preferably 0.1% by mass or more and 95% by mass or less. More preferably, it is 0.5 mass% or more and 90 mass% or less.

The softening temperature of the glass powder is preferably from 200 ° C to 1000 ° C, more preferably from 300 ° C to 900 ° C from the viewpoint of diffusibility at the time of diffusion treatment and dripping.

The shape of the glass powder includes a substantially spherical shape, a flat shape, a block shape, a plate shape, a scaly shape, and the like, and the coating property or the uniform diffusibility of the substrate when the composition for forming the n-type diffusion layer is formed. In general, it is preferably substantially spherical, flat, or plate-shaped. The particle diameter of the glass powder is preferably 100 μm or less. When a glass powder having a particle diameter of 100 μm or less is used, a smooth coating film is easily obtained. Further, the particle diameter of the glass powder is more preferably 50 μm or less. Further, the lower limit is not particularly limited, but is preferably 0.01 μm or more.

Here, the particle diameter of the glass means an average particle diameter, and can be measured by a laser scattering diffraction method particle size distribution measuring apparatus or the like.

The glass powder containing the donor element was produced by the following procedure.

The raw material (for example, the above-mentioned substance containing the donor element and the glass component substance) is first weighed and filled into the crucible. Examples of the material of the crucible include platinum, platinum-rhodium, iridium, aluminum oxide, quartz, carbon, and the like, and are appropriately selected in consideration of the melting temperature, the environment, and the reactivity with the molten material.

Next, a molten metal is prepared by heating in an electric furnace at a temperature corresponding to the composition of the glass. At this time, it is preferable to stir so that the melt becomes uniform.

Then, the obtained melt flows out onto a zirconia substrate, a carbon substrate or the like to vitrify the melt.

Finally, the glass is pulverized to form a powder. A known method such as a jet mill, a bead mill, or a ball mill can be applied to the pulverization.

The content ratio of the glass powder containing the donor element in the composition forming the n-type diffusion layer is 1% by mass or more and 90% from the viewpoints of the coating property, the diffusibility of the donor element, the etching property of the unnecessary glass, and the like. The mass% or less is preferably 5% by mass or more and 70% by mass or less. Further, based on the viewpoint of sufficiently exhibiting a low surface resistance and the immersion time which does not damage the substrate during the etching treatment, the donor element is contained. The content ratio of the glass powder is more preferably 10% by mass or more and 30% by mass or less. When the content ratio of the glass powder exceeds 90% by mass, etching treatment of an unnecessary glass component becomes difficult. When the content ratio of the glass powder is less than 1% by mass, the diffusibility and coatability of the donor element to the substrate are lowered.

In addition, in consideration of the diffusibility of the donor element to the substrate, the content of the substance containing the donor element in the composition forming the n-type diffusion layer is preferably 1% by mass or more, and more preferably 2% by mass or more. Further, even if a certain amount or more of the donor element is added to the composition forming the n-type diffusion layer, the surface sheet resistance having the n-type diffusion layer formed is not less than a certain value and does not decrease.

Hereinafter, the dispersion medium will be described.

The dispersion medium is a medium in which the above glass powder is dispersed in the composition. quality. Specifically, a binder, a solvent or the like is used as a dispersion medium.

As the binder, for example, polyvinyl alcohol, polypropylene decylamine, polyvinyl decylamine, polyvinylpyrrolidone, polyethylene oxide, polysulfonic acid, acrylamide alkylsulfonate can be appropriately selected. Acids, cellulose ethers, cellulose derivatives, carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose, gelatin, starch and starch derivatives, sodium alginate, Sanxian gum Xanthan), guar gum and guar derivatives, scleroglucans and scleroglucan derivatives, tragacanth and xanthan gum derivatives, dextrin and dextrin derivatives, (meth)acrylic resins (meth)acrylate resin (for example, alkyl (meth)acrylic resin, dimethylaminoethyl (meth)acrylic resin, etc.), butadiene resin, styrene resin, and copolymerization thereof Things. And the decane resin can also be appropriately selected. These compounds may be used singly or in combination of two or more kinds thereof.

The molecular weight of the binder is not particularly limited, and is preferably appropriately adjusted in view of the desired viscosity as a composition.

The solvent may, for example, be acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl-isopropyl ketone, methyl-n-butyl ketone, methyl-isobutyl ketone or methyl-n-pentane. Ketone, methyl-n-hexyl ketone, diethyl ketone, dipropyl ketone, di-isobutyl ketone, trimethyl fluorenone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2, 4 a ketone solvent such as pentanedione, acetonylacetone, γ-butyrolactone or γ-valerolactone; for example, diethyl ether, methyl ethyl ether, methyl-n-propyl ether ), di-isopropyl ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, dimethyl dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-butyl Propyl ether, ethylene glycol dibutyl ether, Diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl n-propyl ether, diethylene glycol methyl n-butyl ether, diethylene glycol di-n-butyl 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 (tetraethylene glycol) Glycol) methyl ethyl ether, tetraethylene glycol methyl n-butyl ether, diethylene glycol di-n-butyl ether, tetraethylene glycol methyl n-hexyl ether, tetraethylene glycol di-n-butyl ether, propylene glycol dimethyl ether , propylene glycol diethyl ether, propylene glycol di-n-propyl ether, propylene glycol dibutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol methyl ethyl ether (dipropylene glycol) 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 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, tetradipropylene glycol methyl ethyl ether, tetrapropylene glycol methyl n-butyl ether, dipropylene glycol di-n-butyl ether, tetrapropylene glycol methyl n-hexyl ether An ether solvent such as tetrapropylene glycol di-n-butyl ether; for example, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, second butyl acetate, acetic acid N-amyl ester, second amyl acetate, 3-methoxybutyl acetate, methyl amyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, 2-(2-butoxy) acetate Ethoxyethyl ester, benzyl acetate, Cyclohexyl acetate, methylcyclohexyl acetate, decyl acetate, methyl acetate, ethyl acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, Diethylene glycol mono-n-butyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, ethylene glycol diacetate, methoxy triethylene glycol Acetate, ethyl propionate, n-butyl propionate, isoamyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate Ester solvent; for example, ethylene glycol methyl ether propionate, ethylene glycol ethyl ether propionate, ethylene glycol methyl ether acetate, ethylene glycol ethyl ether acetate, digan Alcohol methyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol-n-butyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether An ether acetate solvent such as acetate, dipropylene glycol methyl ether acetate or dipropylene glycol ethyl ether acetate; for example, acetonitrile, N-methylpyrrolidone, N-ethylpyrrolidone, N -C Aprons of pyrrolidone, N-butylpyrrolidone, N-hexylpyrrolidone, N-cyclohexylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylhydrazine, etc. Proton) a polar solvent; for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, second butanol, tert-butanol, n-pentanol, isoamyl alcohol, 2-methylbutanol , second pentanol, third pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, second hexanol, 2-ethylbutanol, second heptanol, n-octanol, 2-ethylhexanol, second octanol, n-nonanol, n-nonanol, twenty-first alkanol, trimethylnonanol, tetradecanol, heptadecyl alcohol, phenol, ring An alcohol solvent such as hexanol, methylcyclohexanol, benzyl alcohol, ethylene glycol, 1,2-propanediol, 1,3-butanediol, diethylene glycol, dipropylene glycol, triethylene glycol or tripropylene glycol ; for example, B Glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol single n-Hexyl ether, ethoxy triethylene glycol, tetraethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether Ethylene glycol monoether solvent; for example, α-terpinene, α-terpineol, laurylene, allo-ocimene, limonene, dipentene, α-pinene, β-pinene , terpineol (terpineol), fragrant celery ketone, ocimene, celery (terpene) solvent; water, etc. These materials may be used singly or in combination of two or more kinds thereof.

The content ratio of the dispersion medium in the composition forming the n-type diffusion layer is determined in consideration of coatability and donor concentration.

Considering the coating property, the viscosity of the composition forming the n-type diffusion layer is preferably 10 mPa. S above to 1000000mPa. Below S, more preferably 50mPa. S above to 500000mPa. S below.

Further, the composition forming the n-type diffusion layer may also contain other additives. As another additive, the metal which reacts easily with the said glass powder is mentioned, for example.

The composition forming the n-type diffusion layer is applied onto a semiconductor substrate and heat-treated at a high temperature to form an n-type diffusion layer, but at this time, glass is formed on the surface. The glass is immersed in an acid such as hydrofluoric acid and removed, but depending on the type of the glass, there is a glass which is difficult to remove. In this case, by previously adding a metal such as Ag, Mn, Cu, Fe, or Zn, Si, or a combination thereof, the glass can be easily removed after the acid cleaning. Among them, it is preferred to make It is more preferable to use at least one selected from the group consisting of Ag, Si, Cu, Fe, Zn, and Mn, and at least one selected from the group consisting of Ag, Si, and Zn, and particularly preferably Ag.

The content ratio of the metal is preferably adjusted depending on the type of the glass or the type of the metal. Generally, the content of the metal is preferably 0.01% by mass or more and 10% by mass or less based on the glass powder. . Further, the above metal can be used in the form of a metal monomer or a metal oxide.

<Composition for forming p-type diffusion layer>

The composition for forming a p-type diffusion layer of the present invention includes a glass powder (hereinafter sometimes referred to simply as "glass powder") containing at least an acceptor element, and a dispersion medium, and further contains other additives as needed in consideration of coatability and the like. .

Here, the composition forming the p-type diffusion layer means a glass powder containing an acceptor element, and for example, it can be applied to a ruthenium substrate and then subjected to thermal diffusion treatment (calcination/sintering) to form the above-mentioned acceptor element. Thermal diffusion to form a material of the p-type diffusion layer. By using the composition for forming a p-type diffusion layer of the present invention, the step of forming a p ⁺ -type diffusion layer and the step of forming an ohmic contact can be separated, thereby expanding the selection of an electrode material for forming an ohmic contact, and further expanding The choice of electrode construction. For example, when a low-resistance material such as silver is used for the electrode, a low resistance can be achieved with a thin film thickness. Further, the electrode does not need to be formed on the entire surface, and the comb-shaped electrode may be partially formed in a shape such as a comb shape. By forming a partial shape such as a film or a comb shape as described above, it is possible to form a p-type diffusion layer while suppressing internal stress in the ruthenium substrate and occurrence of warpage of the substrate.

Therefore, when the composition for forming a p-type diffusion layer of the present invention is applied, the generation of internal stress generated in the substrate and the warpage of the substrate in the previously widely used method are suppressed, and the previously widely used method is: printing The aluminum paste is then calcined, and a method of obtaining an ohmic contact while making the n-type diffusion layer into a p ⁺ -type diffusion layer.

Further, since the acceptor component in the glass powder is hardly volatilized during firing, it is suppressed that the p-type diffusion layer is formed outside the desired region due to the generation of volatile gas. The reason for this is considered to be that the acceptor component is bound to an element in the glass powder or introduced into the glass, so that it is difficult to volatilize.

In addition, when the content of the glass powder contained in the composition forming the p-type diffusion layer is in the range of 1% by mass or more to 90% by mass or less, the glass layer formed on the p-type diffusion layer can be removed in a short time. . Further, the formation of the p-type diffusion layer is sufficiently performed by diffusion of the acceptor element.

Further, the time required for "forming a p-type diffusion layer" in the present invention means: for forming a p-type diffusion layer plus for removing a glass layer formed on the p-type diffusion layer. Total time. According to this, the time for forming the p-type diffusion layer is shortened by removing the glass layer formed on the p-type diffusion layer in a short time.

The glass powder containing the acceptor element of the present invention will be described in detail.

The term "receptor element" means an element which can form a p-type diffusion layer by being doped into a germanium substrate. As the acceptor element, a Group 13 element of the periodic table can be used, and examples thereof include B (boron), Al (aluminum), and Ga (gallium).

Examples of the acceptor element-containing substance for introducing the acceptor element into the glass powder include B ₂ O ₃ , Al ₂ O ₃ and Ga ₂ O ₃ , preferably selected from B ₂ O ₃ and Al _{2 .} At least one of O ₃ and Ga ₂ O ₃ .

Further, the glass powder containing the acceptor element may be adjusted in composition ratio as needed, thereby controlling the melting temperature, the softening temperature, the glass transition temperature, the chemical durability, and the like. It is preferred to further include the components described below.

Examples of the glass component substance include SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, Tl ₂ O, SnO, ZrO ₂ , and MoO _{3 .} , La ₂ O ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , Y ₂ O ₃ , TiO ₂ , GeO ₂ , TeO ₂ , Lu ₂ O _{3 ,} etc., preferably selected from the group consisting of SiO ₂ , K ₂ O, Na _{At least one of 2} O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, Tl ₂ O, SnO, ZrO ₂ and MoO ₃ .

Specific examples of the glass powder containing the acceptor element include a system including both the above-described acceptor element-containing substance and the above-described glass component substance, and examples thereof include a B ₂ O ₃ —SiO ₂ system (containing an acceptor element). The order of the substance-glass component substance is the same as the above, B ₂ O ₃ -ZnO system, B ₂ O ₃ -PbO system, B ₂ O ₃ individual system, etc., including B ₂ O ₃ as a system containing a receptor element. The Al ₂ O ₃ -SiO ₂ system or the like includes a system in which Al ₂ O _{3 is} a substance containing an acceptor element, and a Ga ₂ O ₃ -SiO ₂ system or the like includes a system in which Ga ₂ O _{3 is} a substance containing an acceptor element. Glass powder.

Further, the glass powder may be a glass powder containing two or more kinds of substances containing an acceptor element, such as an Al ₂ O ₃ -B ₂ O ₃ system or a Ga ₂ O ₃ -B ₂ O ₃ system.

In the above, a glass containing one component or a composite glass including two components is exemplified, but a composite glass of three or more components such as a B ₂ O ₃ -SiO ₂ -Na ₂ O system may be used as needed.

The content ratio of the glass component in the glass powder is preferably set in consideration of the melting temperature, the softening temperature, the glass transition temperature, and the chemical durability. In general, it is preferably 0.1% by mass or more and 95% by mass or less. It is preferably 0.5% by mass or more and 90% by mass or less.

The softening temperature of the glass powder is preferably from 200 ° C to 1000 ° C, more preferably from 300 ° C to 900 ° C from the viewpoint of diffusibility at the time of diffusion treatment and dripping.

Examples of the shape of the glass powder include a substantially spherical shape, a flat shape, a block shape, a plate shape, and a scaly shape, and the coating property or uniform diffusibility of the substrate when the composition for forming the p-type diffusion layer is formed. From the viewpoint, it is preferable to be substantially spherical, flat, or plate-shaped. The particle diameter of the glass powder is preferably 50 μm or less. When a glass powder having a particle diameter of 50 μm or less is used, a smooth coating film is easily obtained. Further, the particle diameter of the glass powder is more preferably 10 μm or less. Further, the lower limit is not particularly limited, but is preferably 0.01 μm or more.

Here, the particle diameter of the glass means an average particle diameter, and can be measured by a laser scattering diffraction method particle size distribution measuring apparatus or the like.

The glass powder containing the acceptor element was produced by the following procedure.

First, the raw material is weighed and filled into the crucible. Examples of the material of the crucible include platinum, platinum-rhodium, iridium, aluminum oxide, quartz, carbon, and the like, and are appropriately selected in consideration of the melting temperature, the environment, and the reactivity with the molten material.

Next, a molten metal is prepared by heating in an electric furnace at a temperature corresponding to the composition of the glass. At this time, it is desirable to make the melt uniform. Stir.

Then, the obtained melt flows out onto a zirconia substrate, a carbon substrate or the like to vitrify the melt.

Finally, the glass is pulverized to form a powder. A known method such as a jet mill, a bead mill, or a ball mill can be applied to the pulverization.

The content ratio of the glass powder containing the acceptor element in the composition of the p-type diffusion layer is 1% by mass or more and 90% or more based on the coating property, the diffusibility of the donor element, and the etching property of the glass. The mass% or less is preferably 5% by mass or more and 70% by mass or less. Further, based on the viewpoint of sufficiently exhibiting a low surface resistance and the immersion time which does not damage the substrate during the etching treatment, the receptor element is contained. The content ratio of the glass powder is more preferably 10% by mass or more and 30% by mass or less. When the content ratio of the glass powder exceeds 90% by mass, etching treatment of an unnecessary glass component becomes difficult. When the content ratio of the glass powder is less than 1% by mass, the diffusibility and coatability of the acceptor to the substrate are lowered.

In addition, in consideration of the diffusibility of the acceptor element to the substrate, the content of the substance containing the acceptor element in the composition forming the p-type diffusion layer is preferably 1% by mass or more, and more preferably 2% by mass or more. Further, even if a certain amount or more of the acceptor element is added to the composition forming the p-type diffusion layer, the surface sheet resistance having the p-type diffusion layer formed is not less than a certain value and does not decrease.

Hereinafter, the dispersion medium will be described.

The dispersion medium in the composition for forming the p-type diffusion layer may be the same as the dispersion medium in the composition for forming the n-type diffusion layer, and the preferred range is also the same. Content ratio in the composition forming the p-type diffusion layer It is determined by considering the coatability and the receptor concentration.

Moreover, considering the coating property, the viscosity of the composition forming the p-type diffusion layer is preferably 10 mPa. S above to 1000000mPa. Below S, more preferably 50mPa. S above to 500000mPa. S below.

<Method for manufacturing n-type diffusion layer and solar cell element>

Next, a method of manufacturing an n-type diffusion layer and a solar cell element of the present invention will be described with reference to FIGS. 1(1) to 1(6). 1(1) to 1(6) are schematic cross-sectional views conceptually showing an example of a manufacturing procedure of a solar cell element of the present invention. In the following drawings, the same components are denoted by the same reference numerals.

In Fig. 1 (1), an alkaline solution is applied to a tantalum substrate as a p-type semiconductor substrate 10 to remove a damaged layer, and a texture structure is obtained by etching.

Specifically, the damaged layer of the crucible surface generated when slicing from the ingot was removed using 20% by mass of caustic soda. Then, etching was performed by a mixture of 1% by mass of caustic soda and 10% by mass of isopropyl alcohol to form a texture structure (the description of the texture structure is omitted in the drawing). By forming a texture structure on the light-receiving surface (surface) side, the solar cell element can promote an optical confinement effect and achieve high efficiency.

In the first embodiment, the composition in which the n-type diffusion layer is formed is applied onto the surface of the p-type semiconductor substrate 10, that is, the surface on which the light-receiving surface is formed, to form the composition layer 11 on which the n-type diffusion layer is formed. In the present invention, the coating method is not limited, and examples thereof include a printing method, a spin coating method, a brush coating method, a spray method, a doctor blade method, a roll coater method, and an ink jet method.

The coating amount of the composition forming the n-type diffusion layer is not particularly limited. For example, the amount of the glass powder can be set to 0.001 g/m ² to 1 g/m ² , preferably 0.015 g/m ² to 0.15 g/m ² .

Further, depending on the composition of the composition forming the n-type diffusion layer, if necessary, a drying step of volatilizing the solvent contained in the composition may be performed after coating. In this case, it is dried for 1 minute to 10 minutes when using a hot plate at a temperature of about 80 ° C to 300 ° C, and dried for about 10 minutes to 30 minutes when using a dryer or the like. The drying conditions depend on the solvent composition of the composition forming the n-type diffusion layer, and are not particularly limited to the above conditions in the present invention.

Further, when the manufacturing method of the present invention is used, the method of manufacturing the p ⁺ -type diffusion layer (high-concentration electric field layer) 14 on the back surface is not limited to the method of converting the n-type diffusion layer into a p-type diffusion layer by aluminum. Any of the previously known methods can be employed to expand the options of the manufacturing method. Therefore, for example, the composition 13 containing an element of Group 13 such as B (boron) can be imparted to form the high-concentration electric field layer 14.

Thereafter, the semiconductor substrate 10 on which the composition layer 11 forming the n-type diffusion layer is formed is subjected to thermal diffusion treatment at 600 ° C to 1200 ° C. By the above thermal diffusion treatment, as shown in FIG. 1 (3), the donor element is diffused into the semiconductor substrate to form the n-type diffusion layer 12. As the heat diffusion treatment, a known continuous furnace, a batch furnace, or the like can be applied. In addition, the furnace environment during the thermal diffusion treatment may be appropriately adjusted to air, oxygen, nitrogen, or the like.

The thermal diffusion treatment time can be appropriately selected in accordance with the content ratio of the donor element contained in the composition forming the n-type diffusion layer. For example, it can be set to 1 minute to 60 minutes, more preferably 2 minutes to 30 minutes.

Since a glass layer (not shown) such as phosphoric acid glass is formed on the surface of the formed n-type diffusion layer 12, the phosphoric acid glass is removed by etching. The etching can be carried out by a known method such as a method of immersing in an acid such as hydrofluoric acid or a method of immersing in an alkali such as caustic soda.

As shown in Fig. 1 (2) and Fig. 1 (3), in the method for forming an n-type diffusion layer of the present invention in which the n-type diffusion layer 12 of the present invention is formed to form the n-type diffusion layer 12, The n-type diffusion layer 12 is formed at a desired portion, and an unnecessary n-type diffusion layer is not formed on the back surface or the side surface.

Therefore, in the method of forming an n-type diffusion layer by a gas phase reaction method widely used previously, a step of etching for removing an unnecessary n-type diffusion layer formed on the side is necessary, however, according to the present invention The manufacturing method does not require a side etching step, thereby simplifying the steps.

Further, in the conventional manufacturing method, it is necessary to convert an unnecessary n-type diffusion layer formed on the back surface into a p-type diffusion layer, and as the conversion method, the following method is employed: coating on the n-type diffusion layer on the back surface A paste of aluminum of a Group 13 element is calcined to diffuse aluminum to the n-type diffusion layer to convert the n-type diffusion layer into a p-type diffusion layer. In the above method, in order to sufficiently convert the n-type diffusion layer into a p-type diffusion layer and further form a high-concentration electric field layer of the p ⁺ layer, a certain amount of aluminum is required, so it is necessary to form the aluminum layer thicker. . However, the coefficient of thermal expansion of aluminum differs greatly from the coefficient of thermal expansion of tantalum used as a substrate. Therefore, during the process of calcination and cooling, a large internal stress is generated in the tantalum substrate, which is a cause of warpage of the tantalum substrate.

The above internal stress versus crystalline grain boundary Boundary) causes damage, resulting in a problem of increased power loss. Further, in the process of transferring the solar cell element in the module process or the connection with a copper wire called a tab wire, the element is easily broken. In recent years, as the slicing technology has been improved, the thickness of the tantalum substrate is being reduced in thickness, and the element tends to be more easily broken.

However, according to the manufacturing method of the present invention, since an unnecessary n-type diffusion layer is not formed on the back surface, conversion from the n-type diffusion layer to the p-type diffusion layer is not required, and it is not necessary to make the aluminum layer thick. As a result, generation or warpage of internal stress in the ruthenium substrate can be suppressed. As a result, an increase in power loss or breakage of the element can be suppressed.

Further, when the manufacturing method of the present invention is used, the method of producing the p ⁺ -type diffusion layer (high-concentration electric field layer) 14 on the back surface is not limited to the method of converting the n-type diffusion layer into a p-type diffusion layer by aluminum. The choice of manufacturing method can also be extended by any method previously known. For example, the p ⁺ -type diffusion layer can also be formed by using the composition for forming a p-type diffusion layer of the present invention.

Further, as will be described later, the material of the surface electrode 20 for the back surface is not limited to aluminum of Group 13, for example, Ag (silver) or Cu (copper) may be applied, and the thickness of the surface electrode 20 on the back surface may be larger than that of the prior art. The thickness is formed thinner.

In FIG. 1 (4), an anti-reflection film 16 is formed on the n-type diffusion layer 12. The anti-reflection film 16 is formed using a well-known technique. For example, when the anti-reflection film 16 is a tantalum nitride film, it is formed by a plasma chemical vapor deposition (CVD) method using a mixed gas of SiH ₄ and NH ₃ as a raw material. At this time, hydrogen diffuses in the crystal to the orbit that does not participate in the bonding of the germanium atom, that is, the dangling bond is hydrogen-bonded, and the defect is passivated (hydrogen passivation).

More specifically, the mixed gas flow rate ratio NH ₃ /SiH ₄ is 0.05 to 1.0, the reaction chamber pressure is 13.3 Pa (0.1 Torr) to 266.6 Pa (2 Torr), and the film forming temperature is 300 ° C to 550 ° C. It is formed under the condition that the frequency of the plasma discharge is 100 kHz or more.

In Fig. 1 (5), a surface electrode 18 is formed by printing and coating a metal paste for a surface electrode on a surface (light-receiving surface) of the anti-reflection film 16 by a screen printing method. The metal paste for a surface electrode contains (1) metal particles and (2) glass particles as essential components, and if necessary, (3) a resin binder, and (4) other additives.

Then, the back surface electrode 20 is also formed on the high-concentration electric field layer 14 on the back surface. As described above, the material or formation method of the back surface electrode 20 in the present invention is not particularly limited. For example, a paste for a back electrode including a metal such as aluminum, silver or copper may be applied and dried to form the back electrode 20. At this time, in order to connect the components in the module process, a silver paste for silver electrode formation may be provided on a part of the back surface.

In Fig. 1 (6), the electrode was calcined to prepare a solar cell element. When calcined in the range of 600 ° C to 900 ° C for several seconds to several minutes, the antireflection film 16 as an insulating film is melted on the surface side by the glass particles contained in the metal paste for the electrode, and further, a part of the surface of the crucible 10 It is also melted, and metal particles (for example, silver particles) in the paste form a contact portion with the tantalum substrate 10 and solidify. Thereby, the formed surface electrode 18 and the germanium substrate 10 are electrically connected. This is called fire through.

The shape of the surface electrode 18 will be described. Surface electrode 18 is made up of sink The strip electrode 30 and the finger electrode 32 that intersects the bus bar electrode 30 are formed. 2(A) is a plan view of the solar cell element formed by the surface electrode 18 as viewed from the surface, including the bus bar electrode 30 and the finger electrode 32 crossing the bus bar electrode 30, and FIG. 2(B) This is a perspective view in which a part of Fig. 2(A) is enlarged.

Such a surface electrode 18 can be formed by, for example, screen printing of the above-described metal paste, plating of an electrode material, vapor deposition of an electrode material by electron beam heating in a high vacuum, or the like. As is well known, the surface electrode 18 including the bus bar electrode 30 and the finger electrode 32 is generally used as an electrode on the light-receiving surface side, and a known method of forming the bus bar electrode and the finger electrode on the light-receiving surface side can be applied.

<P-type diffusion layer and method of manufacturing solar cell element>

Next, a method of manufacturing the p-type diffusion layer and the solar cell element of the present invention will be described.

First, an alkaline solution is applied to a tantalum substrate as a p-type semiconductor substrate to remove the damaged layer, and a texture structure is obtained by etching. In this step, the steps will be described with reference to Fig. 1 (1) in the same manner as the formation of the n-type diffusion layer.

Next, the treatment is performed at 800 ° C to 900 ° C for several tens of minutes in a mixed gas atmosphere of phosphorus oxychloride (POCl ₃ ), nitrogen gas, and oxygen gas to form an n-type diffusion layer in the same manner. At this time, in the method using the phosphorus oxychloride environment, the diffusion of phosphorus also reaches the side surface and the back surface, and the n-type diffusion layer is formed not only on the surface but also on the side surface and the back surface. Therefore, side etching is performed in order to remove the n-type diffusion layer on the side.

Then, the composition for forming the p-type diffusion layer described above is applied to the p-type half. The back surface of the conductor substrate is not the surface of the n-type diffusion layer of the light receiving surface. In the present invention, the coating method is not limited, and examples thereof include a printing method, a spin coating method, a brush coating method, a spray method, a doctor blade method, a roll coater method, and an ink jet method.

The coating amount of the composition forming the p-type diffusion layer is not particularly limited. For example, the coating amount of the glass powder can be set to 0.05 g/m ² to 1.05 g/m ² , preferably 0.065 g/m ² to 0.02 g/m ² .

Further, depending on the composition of the composition forming the p-type diffusion layer, if necessary, a drying step of volatilizing the solvent contained in the composition may be performed after coating. In this case, it is dried for 1 minute to 10 minutes when using a hot plate at a temperature of about 80 ° C to 300 ° C, and dried for about 10 minutes to 30 minutes when using a dryer or the like. The drying conditions depend on the solvent composition of the composition forming the p-type diffusion layer, and are not particularly limited to the above conditions in the present invention.

The semiconductor substrate coated with the composition forming the p-type diffusion layer described above is heat-treated at 600 ° C to 1200 ° C. By this heat treatment, the acceptor element is diffused into the semiconductor substrate to form a p ⁺ -type diffusion layer. A known continuous furnace, a batch furnace, or the like can be applied to the heat treatment. In addition, the furnace environment during the thermal diffusion treatment may be appropriately adjusted to air, oxygen, nitrogen, or the like.

The thermal diffusion treatment time can be appropriately selected in accordance with the content ratio of the acceptor element contained in the composition forming the p-type diffusion layer. For example, it can be set to 1 minute to 60 minutes, more preferably 2 minutes to 30 minutes.

Since the glass layer is formed on the surface of the p ⁺ -type diffusion layer, the glass is removed by etching. The etching can be carried out by a known method such as a method of immersing in an acid such as hydrofluoric acid or a method of immersing in an alkali such as caustic soda.

Here, when the composition for forming a p-type diffusion layer is used in a range in which the content ratio of the glass powder of the present invention is from 1% by mass or more to 90% by mass or less, the glass layer formed on the p-type diffusion layer is removed in a short time. .

Further, in the prior manufacturing method, the aluminum paste was printed on the back side and then calcined to convert the n-type diffusion layer into a p ⁺ -type diffusion layer while obtaining an ohmic contact. However, the aluminum layer formed of the aluminum paste has a low electrical conductivity, and in order to lower the sheet resistance, the aluminum layer usually formed on the entire back surface must have a thickness of about 10 μm to 20 μm after firing. Further, when the aluminum layer having the thickness as described above is formed, since the coefficient of thermal expansion of the crucible differs greatly from the coefficient of thermal expansion of aluminum, a large internal stress is generated in the crucible substrate during the calcination and cooling, and becomes a warp. The reason for the song.

There is a problem that the internal stress causes damage to the crystal grain boundary of the crystal and the power loss increases. Further, in the process of transferring the solar cell element in the module process or the connection with a copper wire called a tab wire, the element is easily broken. In recent years, as the slicing technology has been improved, the thickness of the tantalum substrate is being thinned, and the element tends to be more easily broken.

However, according to the manufacturing method of the present invention, after the n-type diffusion layer is converted into the p ⁺ -type diffusion layer by the composition for forming a p-type diffusion layer of the present invention, an electrode is additionally provided on the p ⁺ -type diffusion layer. Therefore, the material of the electrode for the back surface is not limited to aluminum. For example, Ag (silver) or Cu (copper) may be applied, and the thickness of the electrode on the back surface may be formed thinner than the previous thickness, and it is not necessary to form the entire surface. on. Therefore, internal stress and warpage in the tantalum substrate generated during the calcination and cooling can be reduced.

Then, after the glass is removed by etching, an anti-reflection film is formed on the n-type diffusion layer formed as described above. In this step, the steps will be described with reference to FIG. 1 (4) in the same manner as the formation of the n-type diffusion layer.

On the antireflection film of the surface (light-receiving surface), a metal paste for surface electrode coating was applied by screen printing and dried to form a surface electrode. In this step, the steps will be described with reference to Fig. 1 (5) in the same manner as the formation of the n-type diffusion layer.

Next, a back surface electrode is also formed on the p ⁺ -type diffusion layer on the back surface. The step of forming the back electrode described above is also the same as that described for the n-type diffusion layer.

The above electrode was calcined to prepare a solar cell element. In this step, the steps will be described with reference to FIG. 1 (6) in the same manner as the formation of the n-type diffusion layer.

Further, in the above-described p-type diffusion layer and method for producing a solar cell element, in order to form an n-type diffusion layer on a germanium substrate as a p-type semiconductor substrate, phosphorus oxychloride (POCl ₃ ), nitrogen, and oxygen are used. The mixed gas may be formed using the above-described composition forming the n-type diffusion layer to form an n-type diffusion layer.

In the method of forming the composition for forming an n-type diffusion layer for the formation of an n-type diffusion layer, first, a composition for forming an n-type diffusion layer is applied to a light-receiving surface of a surface of a p-type semiconductor substrate, and is coated on the back surface. The composition for forming a p-type diffusion layer of the present invention is then subjected to thermal diffusion treatment at 600 ° C to 1200 ° C. By the above-described thermal diffusion treatment, the donor element diffuses into the p-type semiconductor substrate to form an n-type diffusion layer, and the acceptor element diffuses on the back surface to form a p ⁺ -type diffusion layer. In addition to the above steps, the solar cell element was fabricated by the same steps as the above method.

In the above, a solar cell element in which an n-type diffusion layer is formed on the surface, a p ⁺ -type diffusion layer is formed on the back surface, and a surface electrode and a back surface electrode are provided on each layer has been described. However, if the present invention is used to form n A back contact solar cell element can also be produced as a composition of the diffusion layer and a composition for forming the p-type diffusion layer.

The back contact type solar cell element is a solar cell element in which all of the electrodes are provided on the back surface to increase the area of the light receiving surface. In other words, in the back contact type solar cell element, it is necessary to form both the n-type diffusion portion and the p ⁺ -type diffusion portion on the back surface to form a pn junction structure. The composition for forming an n-type diffusion layer and the composition for forming a p-type diffusion layer of the present invention can form an n-type diffusion portion and a p-type diffusion portion only at a specific portion, and thus can be preferably applied to a back contact type solar energy. Manufacturing of battery components.

In addition, the entire contents disclosed in Japanese Patent Application No. 2010-144203 and Japanese Application No. 2010-144204 are hereby incorporated by reference.

All of the documents, patent applications, and technical specifications described in the specification are the same as those which are specifically and individually described by reference to the respective documents, patent applications, and technical specifications, which are incorporated herein by reference. In the manual.

[Example]

Hereinafter, examples of the invention will be more specifically described, but the invention is not limited by these examples. In addition, as long as there is no special description in advance, all reagents are used as chemicals. In addition, "%" means "quality" as long as there is no explanation beforehand. %".

[Example 1A]

20 g of powder of P ₂ O ₅ -ZnO system glass (P ₂ O ₅ : 30%, ZnO: 70%) and 0.08 g of ethyl cellulose, 2-(2-acetic acid) using an automatic kneading machine (kneading machine) 2.14 g of 2-butoxyethoxy)ethyl ester was mixed and pasteified to prepare a composition forming an n-type diffusion layer having a glass content of 90%.

Next, the prepared paste was applied onto the surface of the p-type ruthenium substrate by screen printing, and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. Then, the substrate was immersed in 2.5% hydrofluoric acid for 90 minutes to remove the glass layer and subjected to running water washing. After that, it is dried.

The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 11 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer. The sheet resistance of the back surface was an unmeasurable sheet resistance of 1,000,000 Ω/□ or more, and it was determined that substantially no n-type diffusion layer was formed.

Further, the sheet resistance was measured by a four-probe method using a low resistivity meter of the Loresta-EP MCP-T360 type manufactured by Mitsubishi Chemical Corporation.

[Example 2A]

P ₂ O ₅ -ZnO system glass (P ₂ O ₅ : 30%, ZnO: 70%) powder 8 g and ethyl cellulose 0.17 g, 2-(2-butoxyethoxy) acetate using an automatic mortar mixing device 4.27 g of ethyl ester was mixed and pasteified to prepare a composition forming an n-type diffusion layer having a glass content of 65%.

Next, the prepared paste is applied to the p-type by screen printing. The substrate was rubbed on the surface of the substrate and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. Then, the substrate was immersed in 2.5% hydrofluoric acid for 40 minutes to remove the glass layer and subjected to running water washing. After that, it is dried.

The sheet resistance of the surface on the side on which the composition for forming the n-type diffusion layer was applied was 12 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer. The sheet resistance of the back surface was an unmeasurable sheet resistance of 1,000,000 Ω/□ or more, and it was determined that substantially no n-type diffusion layer was formed.

[Example 3A]

P ₂ O ₅ -ZnO system glass (P ₂ O ₅ : 30%, ZnO: 70%) powder 6g and ethyl cellulose 0.91g, acetic acid 2-(2-butoxyethoxy) using an automatic mortar mixing device 23.1 g of ethyl ester was mixed and pasteified to prepare a composition forming an n-type diffusion layer having a glass content of 20%.

Next, the prepared paste was applied onto the surface of the p-type ruthenium substrate by screen printing, and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. Then, the substrate was immersed in 2.5% hydrofluoric acid for 30 minutes to remove the glass layer and subjected to running water washing. After that, it is dried.

The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 11 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer. The sheet resistance of the back surface was an unmeasurable sheet resistance of 1,000,000 Ω/□ or more, and it was determined that substantially no n-type diffusion layer was formed.

[Example 4A]

P ₂ O ₅ -ZnO system glass (P ₂ O ₅ : 30%, ZnO: 70%) powder 3g and ethyl cellulose 1.02g, 2-(2-butoxyethoxy) acetate using an automatic mortar mixing device 26.0 g of ethyl ester was mixed and pasteified to prepare a composition forming an n-type diffusion layer having a glass content of 10%.

Next, the prepared paste was applied onto the surface of the p-type ruthenium substrate by screen printing, and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. Then, the substrate was immersed in 2.5% hydrofluoric acid for 30 minutes to remove the glass layer and subjected to running water washing. After that, it is dried.

The sheet resistance of the surface on the side on which the composition for forming the n-type diffusion layer was applied was 17 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer. The sheet resistance of the back surface was an unmeasurable sheet resistance of 1,000,000 Ω/□ or more, and it was determined that substantially no n-type diffusion layer was formed.

[Example 5A]

P ₂ O ₅ -ZnO system glass (P ₂ O ₅ : 30%, ZnO: 70%) powder 0.5 g with ethyl cellulose 0.36 g, 2-(2-butoxy B acetate) using an automatic mortar mixing device 9.14 g of oxy)ethyl ester was mixed and pasteified to prepare a composition forming an n-type diffusion layer having a glass content of 5%.

Next, the prepared paste was applied onto the surface of the p-type ruthenium substrate by screen printing, and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. Then, the substrate was immersed in 2.5% hydrofluoric acid for 30 minutes to remove the glass layer and subjected to running water washing. After that, it is dried.

The sheet resistance of the surface on the side on which the composition for forming the n-type diffusion layer was applied was 20 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer. back The sheet resistance was an unmeasurable sheet resistance of 1,000,000 Ω/□ or more, and it was judged that the n-type diffusion layer was not substantially formed.

[Example 6A]

P ₂ O ₅ -ZnO system glass (P ₂ O ₅ : 30%, ZnO: 70%) powder 0.3 g with ethyl cellulose 0.56 g, 2-(2-butoxy B acetate) using an automatic mortar mixing device 14.1 g of oxy)ethyl ester was mixed and pasteified to prepare a composition forming an n-type diffusion layer having a glass content of 2%.

Next, the prepared paste was applied onto the surface of the p-type ruthenium substrate by screen printing, and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. Then, the substrate was immersed in 2.5% hydrofluoric acid for 30 minutes to remove the glass layer and subjected to running water washing. After that, it is dried.

The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 56 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer. The sheet resistance of the back surface was an unmeasurable sheet resistance of 1,000,000 Ω/□ or more, and it was determined that substantially no n-type diffusion layer was formed.

[Comparative Example 1A]

20 g of ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ) powder, 3 g of ethyl cellulose and 7 g of 2-(2-butoxyethoxy)ethyl acetate were mixed to prepare a paste to prepare n. The composition of the type of diffusion layer.

Next, the prepared paste was applied onto the surface of the p-type ruthenium substrate by screen printing, and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. Then, the substrate was immersed in hydrofluoric acid for 5 minutes to remove the glass layer. Wash and dry with running water.

The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 14 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer. However, the sheet resistance of the back surface was 50 Ω/□, and an n-type diffusion layer was also formed on the back surface.

[Comparative Example 2A]

1 g of ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ) powder, 7 g of pure water, 0.7 g of polyvinyl alcohol, and 1.5 g of isopropyl alcohol were mixed to prepare a solution to prepare a composition for forming an n-type diffusion layer.

Next, the prepared solution was applied onto the surface of the p-type ruthenium substrate by a spin coater (2000 rpm, 30 seconds), and dried at 150 ° C for 5 minutes on a hot plate. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. Then, the substrate was immersed in hydrofluoric acid for 5 minutes to remove the glass layer, followed by washing with running water and drying.

The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 10 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer. However, the sheet resistance of the back surface was 100 Ω/□, and an n-type diffusion layer was also formed on the back surface.

[Comparative Example 3A]

30 g of powder of P ₂ O ₅ -ZnO system glass (P ₂ O ₅ : 30%, ZnO: 70%) and 0.06 g of ethyl cellulose and 1.52 g of 2-(2-butoxyethoxy)ethyl acetate These were mixed and pasteified to prepare a composition which forms an n-type diffusion layer having a glass content of 95%.

Next, the prepared paste was applied onto the surface of the p-type ruthenium substrate by screen printing, and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. The substrate was then immersed in 2.5% hydrofluoric acid for 90 minutes to remove the glass layer. After that, it was washed with running water and dried.

The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 10 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer. The sheet resistance of the back surface was an unmeasurable sheet resistance of 1,000,000 Ω/□ or more, and it was determined that substantially no n-type diffusion layer was formed.

[Comparative Example 4A]

P ₂ O ₅ -ZnO system glass (P ₂ O ₅ : 30%, ZnO: 70%) powder 0.05g and ethyl cellulose 0.38g, 2-(2-butoxyethoxy)ethyl acetate 9.57 g was mixed and pasteified to prepare a composition forming an n-type diffusion layer having a glass content of 0.5%.

Next, the prepared paste was applied onto the surface of the p-type ruthenium substrate by screen printing, and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. Then, the substrate was immersed in 2.5% hydrofluoric acid for 30 minutes to remove the glass layer and subjected to running water washing. After that, it is dried.

The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 186 Ω/□, and the diffusion of P (phosphorus) was not sufficient. The sheet resistance of the back surface was an unmeasurable sheet resistance of 1,000,000 Ω/□ or more, and it was determined that substantially no n-type diffusion layer was formed.

[Example 1B]

B ₂ O ₃ -SiO ₂ -R ₂ O (R:Na, K, Li)-based glass powder (trade name: TMX-603C, manufactured by Tokan Material Technology Co., Ltd.) 20 g using an automatic mortar mixing device 0.08 g of ethyl cellulose and 2.14 g of 2-(2-butoxyethoxy)ethyl acetate were mixed and pasteified to prepare a composition for forming a p-type diffusion layer having a glass content of 90%.

Next, by screen printing, the applied amount of the paste was applied to the surface of the p-type germanium substrate having the n-type diffusion layer formed thereon at a coating amount of 0.065 g/m ² , and at 150 ° C. Dry on a hot plate for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. Then, the substrate was immersed in 2.5% hydrofluoric acid for 90 minutes to remove the glass layer, washed by running water, and dried.

The sheet resistance of the surface on the side on which the composition for forming the p-type diffusion layer was applied was 30 Ω/□, and B (boron) was diffused to form a p-type diffusion layer. In addition, warpage of the substrate did not occur.

[Example 2B]

B ₂ O ₃ -SiO ₂ -R ₂ O (R:Na, K, Li)-based glass powder (trade name: TMX-603C, manufactured by Tokan Material Technology Co., Ltd.) 8 g using an automatic mortar mixing device 0.17 g of ethyl cellulose and 4.27 g of 2-(2-butoxyethoxy)ethyl acetate were mixed and pasteified to prepare a composition for forming a p-type diffusion layer having a glass content of 65%.

Next, the prepared paste was applied onto the surface of the p-type ruthenium substrate having the n-type diffusion layer formed thereon by screen printing, and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. Then, the substrate was immersed in 2.5% hydrofluoric acid for 40 minutes to remove the glass layer, washed with running water, and dried.

The sheet resistance of the surface on the side on which the composition for forming the p-type diffusion layer was applied was 48 Ω/□, and B (boron) was diffused to form a p-type diffusion layer. In addition, No warpage of the substrate occurred.

[Example 3B]

B ₂ O ₃ -SiO ₂ -R ₂ O (R:Na, K, Li)-based glass powder (trade name: TMX-603C, manufactured by Tokan Material Technology Co., Ltd.) 6 g using an automatic mortar mixing device 0.91 g of ethyl cellulose and 23.1 g of 2-(2-butoxyethoxy)ethyl acetate were mixed and pasteified to prepare a composition for forming a p-type diffusion layer having a glass content of 20%.

Next, the prepared paste was applied onto the surface of the p-type ruthenium substrate having the n-type diffusion layer formed thereon by screen printing, and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. Then, the substrate was immersed in 2.5% hydrofluoric acid for 30 minutes to remove the glass layer, washed with running water, and dried.

The sheet resistance of the surface on the side on which the composition for forming the p-type diffusion layer was applied was 75 Ω/□, and B (boron) was diffused to form a p-type diffusion layer. In addition, warpage of the substrate did not occur.

[Example 4B]

B ₂ O ₃ -SiO ₂ -R ₂ O (R:Na, K, Li)-based glass powder (trade name: TMX-603C, manufactured by Tokan Material Technology Co., Ltd.) 3 g using an automatic mortar mixing device 1.02 g of ethyl cellulose and 26.0 g of 2-(2-butoxyethoxy)ethyl acetate were mixed and pasteified to prepare a composition which forms a p-type diffusion layer having a glass content of 10%.

Next, the prepared paste was applied onto the surface of the p-type ruthenium substrate having the n-type diffusion layer formed thereon by screen printing, and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, in an electric furnace set to 1000 ° C The thermal diffusion treatment was carried out for 10 minutes. Then, the substrate was immersed in 2.5% hydrofluoric acid for 30 minutes to remove the glass layer, washed with running water, and dried.

The sheet resistance of the surface on the side on which the composition for forming the p-type diffusion layer was applied was 83 Ω/□, and B (boron) was diffused to form a p-type diffusion layer. In addition, warpage of the substrate did not occur.

[Example 5B]

B ₂ O ₃ -SiO ₂ -R ₂ O (R:Na, K, Li)-based glass powder (trade name: TMX-603C, manufactured by Tokan Material Technology Co., Ltd.) 0.5 using an automatic mortar mixing device g and 0.3 g of ethyl cellulose and 9.14 g of 2-(2-butoxyethoxy)ethyl acetate were mixed and pasteified to prepare a composition which forms a p-type diffusion layer having a glass content of 5%.

Next, the prepared paste was applied onto the surface of the p-type ruthenium substrate having the n-type diffusion layer formed thereon by screen printing, and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. Then, the substrate was immersed in 2.5% hydrofluoric acid for 30 minutes to remove the glass layer, washed with running water, and dried.

The sheet resistance of the surface on the side on which the composition for forming the p-type diffusion layer was applied was 110 Ω/□, and B (boron) was diffused to form a p-type diffusion layer. In addition, warpage of the substrate did not occur.

[Example 6B]

B ₂ O ₃ -SiO ₂ -R ₂ O (R:Na, K, Li)-based glass powder (trade name: TMX-603C, manufactured by Tokan Material Technology Co., Ltd.) 0.3 using an automatic mortar mixing device g and 0.56 g of ethyl cellulose and 14.1 g of 2-(2-butoxyethoxy)ethyl acetate were mixed and pasteified to prepare a composition which forms a p-type diffusion layer having a glass content of 2%.

Next, the prepared paste was applied onto the surface of the p-type ruthenium substrate having the n-type diffusion layer formed thereon by screen printing, and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. Then, the substrate was immersed in 2.5% hydrofluoric acid for 30 minutes to remove the glass layer, washed with running water, and dried.

The sheet resistance of the surface on the side on which the composition for forming the p-type diffusion layer was applied was 160 Ω/□, and B (boron) was diffused to form a p-type diffusion layer. In addition, warpage of the substrate did not occur.

[Comparative Example 1B]

B ₂ O ₃ -SiO ₂ -R ₂ O (R:Na, K, Li)-based glass powder (trade name: TMX-603C, manufactured by Tokan Material Technology Co., Ltd.) 30 g using an automatic mortar mixing device 0.06 g of ethyl cellulose and 1.52 g of 2-(2-butoxyethoxy)ethyl acetate were mixed and paste-formed to prepare a composition which forms a p-type diffusion layer having a glass content of 95%.

Next, the prepared paste was applied onto the surface of the p-type ruthenium substrate having the n-type diffusion layer formed thereon by screen printing, and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. The substrate was then immersed in 2.5% hydrofluoric acid for 90 minutes to remove the glass layer. After that, it was washed with running water and dried.

The sheet resistance of the surface on the side where the composition for forming the p-type diffusion layer was applied was 42 Ω/□, and B (boron) was diffused.

[Comparative Example 2B]

B ₂ O ₃ -SiO ₂ -R ₂ O (R:Na, K, Li)-based glass powder (trade name: TMX-603C, manufactured by Tokan Material Technology Co., Ltd.) 0.05 using an automatic mortar mixing device g and 0.38 g of ethyl cellulose and 9.57 g of 2-(2-butoxyethoxy)ethyl acetate were mixed and pasteified to prepare a composition for forming a p-type diffusion layer having a glass content of 0.5%.

Next, the prepared paste was applied onto the surface of the p-type ruthenium substrate having the n-type diffusion layer formed thereon by screen printing, and dried on a hot plate at 150 ° C for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 °C. Then, the substrate was immersed in 2.5% hydrofluoric acid for 90 minutes to remove the glass layer, washed by running water, and dried.

The sheet resistance of the surface on the side on which the composition for forming the p-type diffusion layer was applied was 320 Ω/□, and B (boron) was not sufficiently diffused.

10‧‧‧p type semiconductor substrate

11‧‧‧ Forming the composition layer of the n-type diffusion layer

12‧‧‧n type diffusion layer

13‧‧‧Composition

14‧‧‧p ⁺ diffusion layer

16‧‧‧Anti-reflective film

18‧‧‧ surface electrode

20‧‧‧Back electrode

30‧‧‧Bus Bar Electrode

32‧‧‧ finger electrode

1(1) to 1(6) are cross-sectional views conceptually showing an example of a manufacturing procedure of a solar cell element of the present invention.

Fig. 2(A) is a plan view of the solar cell element viewed from the surface, and Fig. 2(B) is a perspective view showing a part of Fig. 2(A) in an enlarged manner.

10‧‧‧p type semiconductor substrate

11‧‧‧ Forming the composition layer of the n-type diffusion layer

12‧‧‧n type diffusion layer

13‧‧‧Composition

14‧‧‧p ⁺ diffusion layer

16‧‧‧Anti-reflective film

18‧‧‧ surface electrode

20‧‧‧Back electrode

Claims (13)

A composition for forming an impurity diffusion layer, comprising: a glass powder containing a donor element or an acceptor element; and a dispersion medium, wherein a content ratio of the glass powder is in a range of from 1% by mass to 90% by mass, and the above-mentioned impurity is formed The composition of the diffusion layer is a manufacturing method for the impurity diffusion layer, and the method for producing the impurity diffusion layer includes the step of applying the composition for forming the impurity diffusion layer on the semiconductor substrate to form a composition layer for forming the impurity diffusion layer. And a step of heat-treating the semiconductor substrate on which the composition layer for forming the impurity diffusion layer is formed to form an impurity diffusion layer in the semiconductor substrate, and removing the glass formed on the surface of the impurity diffusion layer. A composition for forming an n-type diffusion layer, comprising: a glass powder containing a donor element; and a dispersion medium, wherein a content ratio of the glass powder is in a range of from 1% by mass to 90% by mass, and the n-type diffusion layer is formed as described above In the method for producing an n-type diffusion layer, the method for manufacturing the n-type diffusion layer includes applying the composition forming the n-type diffusion layer on the semiconductor substrate to form a composition layer forming the n-type diffusion layer. a step of heat-treating the semiconductor substrate on which the composition layer forming the n-type diffusion layer is formed to form an n-type diffusion layer in the semiconductor substrate, and removing the n-type diffusion layer formed on the semiconductor substrate The steps of the surface of the glass. The composition for forming an n-type diffusion layer according to claim 2, wherein the donor element is at least one selected from the group consisting of P (phosphorus) and Sb (antimony). The composition for forming an n-type diffusion layer according to the second aspect of the invention, wherein the glass powder containing the donor element comprises a substance containing a donor element and a glass component, and the substance containing the donor element is selected from the group consisting of P At least one of ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ , the glass component is selected from the group consisting of SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO. At least one of PbO, CdO, SnO, ZrO ₂ and MoO ₃ . The composition for forming an n-type diffusion layer as described in claim 2, further comprising at least one metal selected from the group consisting of Ag, Cu, Fe, Zn, and Mn, Si, or a combination thereof. The composition for forming an n-type diffusion layer according to claim 5, wherein the metal is Ag (silver). A method of producing an n-type diffusion layer, comprising: coating a semiconductor substrate with a composition for forming an n-type diffusion layer according to any one of claims 2 to 6; and performing thermal diffusion The steps of processing. A method of manufacturing a solar cell element, comprising: coating a semiconductor substrate with a composition for forming an n-type diffusion layer according to any one of claims 2 to 6; performing thermal diffusion treatment a step of forming an n-type diffusion layer; A step of forming an electrode on the formed n-type diffusion layer. A composition for forming a p-type diffusion layer, comprising: a glass powder containing an acceptor element; and a dispersion medium, wherein a content ratio of the glass powder is in a range of from 1% by mass to 90% by mass, and the p-type diffusion layer is formed as described above The composition is a method for producing a p-type diffusion layer, and the method for manufacturing the p-type diffusion layer includes applying the composition forming the p-type diffusion layer on the semiconductor substrate to form a composition layer forming the p-type diffusion layer. a step of heat-treating the semiconductor substrate on which the composition layer forming the p-type diffusion layer is formed, forming a p-type diffusion layer in the semiconductor substrate, and removing the glass formed on the surface of the p-type diffusion layer . The composition for forming a p-type diffusion layer according to claim 9, wherein the acceptor element is at least one selected from the group consisting of B (boron), Al (aluminum), and Ga (gallium). The composition for forming a p-type diffusion layer according to claim 9, wherein the glass powder containing the acceptor element includes a substance containing an acceptor element and a glass component substance, and the substance containing the acceptor element is selected from the group consisting of B At least one of ₂ O ₃ , Al ₂ O ₃ and Ga ₂ O ₃ , the glass component is selected from the group consisting of SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO. At least one of PbO, CdO, Tl ₂ O, SnO, ZrO ₂ and MoO ₃ . A method for manufacturing a p-type diffusion layer, comprising: A step of forming a composition for forming a p-type diffusion layer as described in any one of claims 9 to 11 on a semiconductor substrate; and a step of performing a thermal diffusion treatment. A method of manufacturing a solar cell element, comprising: coating a semiconductor substrate with a composition for forming a p-type diffusion layer according to any one of claims 9 to 11; performing thermal diffusion treatment a step of forming a p-type diffusion layer; and a step of forming an electrode on the formed p-type diffusion layer.