TWI482302B - Composition for forming n-type diffusion layer, method for forming n-type diffusion layer, and method for producing photovoltaic cell element - Google Patents

Description

Composition for forming n-type diffusion layer, method for producing n-type diffusion layer, and method for producing solar cell element

The present invention relates to a composition for forming an n-type diffusion layer of a solar cell element, a method for producing an n-type diffusion layer, and a method for manufacturing a solar cell element. More specifically, the present invention relates to a semiconductor substrate. A technique in which a specific portion of the germanium substrate forms an n-type diffusion layer.

The manufacturing steps of the prior 矽 solar cell element will be described.

First, in order to promote the optical confinement effect and to achieve high efficiency, a p-type germanium substrate having a texture structure is prepared, and then 800 ° C in a mixed gas atmosphere of phosphorus oxychloride (POCl ₃ ), nitrogen, and oxygen. The treatment was performed at 900 ° C for several tens of minutes to form an n-type diffusion layer in the same manner. In this prior method, since phosphorus is diffused by using a mixed gas, an n-type diffusion layer is formed not only on the surface but also on the side surface and the back surface. For these reasons, side etching is required to remove the side n-type diffusion layer. Further, the need to convert back surface of the n-type diffusion layer into the p ⁺ -type diffusion layer, thus giving an aluminum paste on the back surface of the n-type diffusion layer, by diffusion of aluminum to the n-type diffusion layer is converted into a p ⁺ -type diffusion layer .

On the other hand, in the field of the manufacture of semiconductors, for example, as disclosed in Japanese Laid-Open Patent Publication No. 2002-75894, it is proposed to apply phosphorus pentoxide (P ₂ O ₅ ) or ammonium dihydrogen phosphate by coating. A method of forming a n-type diffusion layer by a solution of a phosphate such as NH ₄ H ₂ PO ₄ ). However, since the solution is used in the method, the diffusion of phosphorus is also spread to the side surface and the back surface in the same manner as the gas phase reaction method using the above mixed gas, and not only the n-type diffusion layer is formed on the surface but also the side surface and the back surface are formed. Type diffusion layer.

As described above, when the n-type diffusion layer is formed, in the gas phase reaction using phosphorus oxychloride, an n-type diffusion layer is formed not only on the side (usually the light-receiving surface or the surface) where the n-type diffusion layer is originally required, but also An n-type diffusion layer is also formed on the other side (non-light-receiving surface, back surface) or side surface. Further, in the method of applying a solution containing a phosphate and performing thermal diffusion, an n-type diffusion layer is formed on the surface other than the gas phase reaction method. 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 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 a solar cell element using a germanium substrate, which can be more efficiently specified without forming an unnecessary n-type diffusion layer. The n-type diffusion layer forming composition of the n-type diffusion layer, the manufacturing method of the n-type diffusion layer, and the manufacturing method of the solar cell element.

The method for solving the above problems is as follows.

<1> A composition for forming an n-type diffusion layer, comprising a glass powder containing a donor element and having a softening temperature of 300 ° C to 950 ° C, and a dispersion medium.

<2> The composition for forming an n-type diffusion layer according to the above <1>, wherein the donor element is at least one selected from the group consisting of P (phosphorus) and Sb (antimony).

<3> The composition for forming an n-type diffusion layer according to the above <1> or <2>, wherein the glass powder containing the above-mentioned donor element comprises: selected from the group consisting of P ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ at least one substance containing a donor element, and is selected from _{SiO 2, K 2 O, Na} 2 O, Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO 2 At least one glass component substance of CeO ₂ and MoO ₃ .

The composition for forming an n-type diffusion layer according to any one of the above-mentioned items, wherein the crystallization temperature of the glass powder is further 1050 ° C or higher.

<5> A method of producing an n-type diffusion layer, comprising: a step of forming a composition for forming an n-type diffusion layer according to any one of the above <1> to <4>, and a method of performing thermal diffusion treatment step.

<6> A method for producing a solar cell element, comprising the step of applying a composition for forming an n-type diffusion layer according to any one of the above <1> to <4> on a semiconductor substrate, and performing thermal diffusion a step of forming an n-type diffusion layer and a step of forming an electrode on the n-type diffusion layer formed.

[Effects of the Invention]

According to the present invention, in the manufacturing step of the solar cell element using the germanium substrate, the n-type diffusion layer can be formed more efficiently in a specific portion without forming an unnecessary n-type diffusion layer.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

First, the composition for forming an n-type diffusion layer of the present invention will be described. Next, an n-type diffusion layer using a composition for forming an n-type diffusion 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 the present specification, "to" means a range including the numerical values described before and after the minimum value and the maximum value. Further, in the present specification, when the amount of each component in the composition is referred to, when a plurality of substances corresponding to the respective components are present in the composition, unless otherwise specified, the presence of the composition is indicated. The total amount of the plurality of substances.

The composition for forming an n-type diffusion layer of the present invention includes a glass powder (hereinafter, simply referred to as "glass powder") having at least a donor element and having a softening temperature of 300 ° C to 950 ° C, and a dispersion medium, and further considering the coating. Cloth, etc., may also contain other additives as needed.

Here, the composition forming the n-type diffusion layer means that a donor element is contained, and the donor element can be thermally diffused by, for example, being applied to a ruthenium substrate and then subjected to thermal diffusion treatment (calcination). A material that forms an 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 to which a composition for forming an n-type diffusion layer is imparted, and a composition for forming an n-type diffusion layer is not imparted. The back or side faces form an undesired n-type diffusion layer.

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. In addition, 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 undesired product and does not add a step even if compared with the prior method.

Further, since the donor component in the glass powder is hard to be sublimated during 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 volatile 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 (embedded) 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 and a phosphate-containing method.

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, a group 15 element can be used, and examples thereof include P (phosphorus), Sb (antimony), Bi (antimony), and As (arsenic). From the viewpoints of safety, easiness 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 . To use at least one selected from the group consisting of P ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ .

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 contain 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 , CeO ₂ , 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 At least one of Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO ₂ , CeO 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 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 -CeO ₂ system, P ₂ O ₅ -SnO system, P ₂ O ₅ -GeO ₂ system, P ₂ O ₅ -TeO ₂ system, etc., containing P ₂ O ₅ as a containing A system of a substance of a bulk element, which comprises Sb ₂ O ₃ instead of P ₂ O _{5 of the} above system containing P ₂ O ₅ as a glass powder of a system containing a substance of 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.

In the above, a composite glass containing two components is exemplified, but a glass powder containing three or more components such as P ₂ O ₅ —SiO ₂ —CeO ₂ , P ₂ O ₅ —SiO ₂ —CaO, or the like may be exemplified. .

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, the crystallization temperature, and the chemical durability. In general, it is preferably 0.1% by mass or more and 95% by mass. % or less, more preferably 0.5% by mass or more and 90% by mass or less.

Specifically, when it is a P ₂ O ₅ -CeO ₂ system glass, the content ratio of CeO ₂ is preferably from 1% by mass to 50% by mass, more preferably from 3% by mass to 40% by mass. By the content ratio, the n-type diffusion layer can be formed more uniformly.

The softening temperature of the glass powder is important in that the donor element is more efficiently diffused into the ruthenium substrate during the thermal diffusion treatment described later, and a more uniform n-type diffusion layer is obtained. In the present invention, the softening temperature is from 300 ° C to 950 ° C, preferably from 350 ° C to 900 ° C, more preferably from 370 ° C to 850 ° C, still more preferably from 390 ° C to 800 ° C.

When the softening temperature of the glass powder is less than 300° C., the glass component is easily crystallized during the thermal diffusion treatment at a high temperature, and the etching removal property of the glass component after the thermal diffusion treatment tends to be lowered. There is a tendency that the donor element is easily volatilized due to a decrease in melting point, and an n-type diffusion layer is likely to be formed in an unnecessary portion during thermal diffusion treatment. Further, when the softening temperature of the glass powder exceeds 950 ° C, the glass hardly softens during the heat diffusion treatment, and the glass powder maintains a granular shape. Therefore, the glass component is not uniformly covered on the ruthenium substrate in the microscopic state, and the donor body is applied. When the element is diffused, the formability of the n-type diffusion layer tends to be uneven, and the sheet resistance value may increase.

Further, the softening temperature of the glass powder can be easily measured based on the endothermic peak by a well-known differential thermal analyzer (DTA).

Further, in the present invention, the crystallization temperature of the glass powder is preferably 1050 ° C or higher, more preferably 1100 ° C or higher, and still more preferably 1200 ° C or higher. When the crystallization temperature is 1050 ° C or higher, crystallization of the glass component during thermal diffusion treatment is suppressed. Thereby, the residual of the crystallizing compound is suppressed in the glass component etching removal step after the thermal diffusion treatment, and the etching removal property of the glass component is improved.

Further, the crystallization temperature of the glass powder can be easily measured by a known differential thermal analyzer (DTA) based on the peak of heat generation.

The shape of the glass powder includes a substantially spherical shape, a flat shape, a block shape, a plate shape, a scale shape, and the like, and the coating property or uniform diffusion property to the substrate when the composition for forming the n-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 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.

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 preferable to stir so that the melt becomes uniform.

Then, the obtained melt flows out onto a graphite plate, a platinum plate, a platinum-ruthenium alloy plate, a zirconia plate 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 determined in consideration of coatability, diffusibility of the donor element, and the like. In general, the content ratio of the glass powder in the composition forming the n-type diffusion layer is preferably 0.1% by mass or more and 95% by mass or less, more preferably 1% by mass or more and 90% by mass or less, and still more preferably 1.5% by mass or less. The mass% or more is 85% by mass or less, and particularly preferably 2% by mass or more and 80% by mass or less.

Next, the dispersion medium will be described.

The dispersion medium refers to a medium in which the glass powder is dispersed in the composition. 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 alkyl chloride can be suitably selected. Sulfonic acid, cellulose ethers, cellulose derivatives, carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose, gelatin, starch and starch derivatives, sodium alginate, Sanxian gum (xanthan), guar and guar derivatives, scleroglucan and scleroglucan derivatives, tragacanth and tragacanth derivatives, dextrin and dextrin derivatives, (Meth)acrylic resin, (meth) acrylate resin (for example, alkyl (meth) acrylate resin, dimethylaminoethyl methacrylate resin, etc.), butadiene resin, styrene resin Further, in addition to the copolymers, a rhodium oxide resin may be suitably selected. These may be used alone or in combination of two or more.

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

Examples of the solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-isopropyl ketone, methyl-n-butyl ketone, methyl-isobutyl ketone, and methyl group. N-pentyl ketone, methyl-n-hexyl ketone, diethyl ketone, dipropyl ketone, di-isobutyl ketone, trimethyl fluorenone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2 a ketone solvent such as 4-pentanedione or acetonylacetone; 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-propyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethyl 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 Alcohol 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-positive Dibutyl ether, triethylene glycol di-n-butyl ether, triethylene glycol methyl-positive Ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetra-diethylene 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 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, three Propylene glycol diethyl ether, tripropylene glycol methyl ethyl ether, tripropylene glycol methyl-n-butyl ether, tripropylene glycol di-n-butyl ether, tripropylene glycol methyl-n-hexyl ether, tetrapropylene glycol dimethyl ether, tetrapropylene glycol diethyl ether, four- An ether solvent such as dipropylene glycol methyl ethyl ether, tetrapropylene glycol methyl-n-butyl ether, dipropylene glycol di-n-butyl ether, tetrapropylene glycol methyl-n-hexyl ether or tetrapropylene glycol di-n-butyl ether; methyl acetate, acetic acid Ethyl ester, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, second butyl acetate, B N-amyl ester, second amyl acetate, 3-methoxybutyl acetate, methyl amyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, 2-(2-butoxy) acetate Ethoxy)ethyl ester, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, decyl acetate, methyl acetonitrile, ethyl acetate, diethylene glycol methyl ether, diethyl acetate Glycol monoethyl ether, diethylene glycol-n-butyl ether acetate, dipropylene glycol methyl ether acetate, dipropylene glycol ethyl acetate, ethylene glycol diacetate, ethoxy triethylene glycol acetate, ethyl propionate, C N-butyl acrylate, isoamyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, ethylene glycol methyl ether propionate, Ethylene glycol ether propionate, ethylene glycol methyl ether acetate, ethylene glycol ethyl ether acetate, diethylene glycol methyl ether acetate, diethylene glycol diethyl ether acetate, diethylene glycol - positive Butyl ether acetate, propylene glycol methyl ether acetate, propylene glycol diethyl ether acetate, propylene glycol propyl ether acetate, dipropylene glycol methyl ether acetate, dipropylene glycol diethyl ether acetate, γ-butyrolactone, γ- An ester solvent such as lactone; acetonitrile, N-methylpyrrolidone, N-ethylpyrrolidone, N-propylpyrrolidone, N-butylpyrrolidone, N-hexylpyrrolidone, N-cyclohexylpyrrolidone, Aprotic polar solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethylhydrazine; methanol, ethanol, n-propanol, isopropanol, n-butanol, Isobutanol, second butanol, third 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, second - sec-undecyl alcohol, trimethyl sterol, second-tetradecanol, second heptadecyl alcohol, phenol, cyclohexanol, methylcyclohexanol, benzyl alcohol, ethylene glycol, Alcoholic solvents such as 1,2-propanediol, 1,3-butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol; ethylene glycol methyl ether, ethylene glycol ether, ethylene glycol monobenzene Ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-positive a glycol monoether solvent such as ether, ethoxytriethylene glycol, tetraethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether or tripropylene glycol monomethyl ether; Terpinene, α-terpineol, laurylene, allo-ocimene, limonene, dipentene, α-pinene, β-pinene, terpineol, fragrant celery, a terpene solvent such as basilene or water celery; water. These may be used alone or in combination of two or more.

When the composition for forming the n-type diffusion layer is formed, from the viewpoint of coatability of the substrate, α-terpineol, diethylene glycol mono-n-butyl ether, and acetic acid 2-(2- are preferable. Butoxyethoxy)ethyl ester.

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.

The viscosity of the composition forming the n-type diffusion layer is preferably from 10 mPa·S or more to 1,000,000 mPa·s or less, more preferably from 50 mPa·S or more to 500,000 mPa·s or less, in view of coatability. .

Next, a method of manufacturing the n-type diffusion layer and the 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, and the composition layer 11 on which the n-type diffusion layer is formed 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 may be set to 0.01 g/m ² to 100 g/m ² , preferably 0.1 g/m ² to 10 g/m ² .

Further, depending on the composition of the composition forming the n-type diffusion layer, a drying step for volatilizing the solvent contained in the composition after coating may be provided. In this case, it is dried at a temperature of about 80 ° C to 300 ° C for 1 minute to 10 minutes when using a hot plate, 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 conversion of the formed n-type diffusion layer into a p-type diffusion layer by aluminum. The method can also be extended by any method previously known to expand the selection of the manufacturing method. Therefore, for example, the composition layer 13 can be formed by imparting an element containing Group 13 such as B (boron), thereby forming the high-concentration electric field layer 14.

The composition 13 containing the element of Group 13 such as B (boron) may, for example, be a glass powder containing an acceptor element instead of a glass powder containing a donor element, and be the same as the composition forming the n-type diffusion layer. The composition of the p-type diffusion layer is formed in a manner. The acceptor element may be an element of Group 13 and examples thereof include B (boron), Al (aluminum), and Ga (gallium). Further, the glass powder containing the acceptor element is preferably at least one selected from the group consisting of B ₂ O ₃ , Al ₂ O ₃ and Ga ₂ O ₃ .

Further, the method of applying the composition for forming the p-type diffusion layer to the back surface of the ruthenium substrate is the same as the method of applying the composition for forming the n-type diffusion layer to the ruthenium substrate.

The composition for forming the p-type diffusion layer applied to the back surface is thermally diffused in the same manner as the thermal diffusion treatment of the composition for forming the n-type diffusion layer, which will be described later, whereby the high-concentration electric field layer 14 can be formed on the back surface. . Further, it is preferred that the thermal diffusion treatment of the composition forming the p-type diffusion layer be performed simultaneously with the thermal diffusion treatment of the composition forming the n-type diffusion layer.

Then, 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 this 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. Further, the furnace environment during the heat diffusion treatment may be appropriately adjusted to air, oxygen, nitrogen, or the like as needed.

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, or the softening temperature of the glass powder. 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 glass layer 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.

In the method of forming the n-type diffusion layer of the present invention in which the n-type diffusion layer 12 is formed using the composition 11 for forming an n-type diffusion layer of the present invention as shown in FIG. 1 (2) and FIG. 1 (3), only The desired portion forms the n-type diffusion layer 12 without forming an unnecessary n-type diffusion layer on the back side or the side surface.

Therefore, in the previously widely used method of forming an n-type diffusion layer by a gas phase reaction method, a side etching step is required in order to remove an unnecessary n-type diffusion layer formed on the side, but according to the manufacturing method of the present invention, The side etching step is not required, thereby simplifying the steps.

Further, in the prior 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 this 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 ⁺ -type diffusion layer, a certain amount of aluminum is required, so it is necessary to form an aluminum layer. Thicker. However, since the coefficient of thermal expansion of aluminum differs greatly from the coefficient of thermal expansion of tantalum as a substrate, a large internal stress is generated in the tantalum substrate during the firing and cooling, which causes the warpage of the tantalum substrate.

This internal stress causes a problem that the crystal grain boundary of the crystal is damaged and the power loss is increased. 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 solar cell 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 solar cell 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, it is not necessary to convert the n-type diffusion layer into a p-type diffusion layer without thickening the aluminum layer. 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 solar cell element can be suppressed.

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 conversion of the formed n-type diffusion layer into a p-type diffusion layer by aluminum. The method can also be extended by any method previously known to expand the selection of the manufacturing method.

Preferably, for example, a glass powder containing an acceptor element is used instead of the glass powder containing the donor element, and a composition for forming a p-type diffusion layer which is formed in the same manner as the composition for forming the n-type diffusion layer is applied to the crucible. The back surface of the substrate (the surface opposite to the surface on which the composition forming the n-type diffusion layer is applied) is subjected to a firing treatment to form a p ⁺ -type diffusion layer (high-concentration electric field layer) 14 on the back surface.

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 pressure in the reaction chamber is 0.1 Torr to 2 Torr, and the temperature at the time of film formation is 300 to 550 ° C, which is used for discharge of plasma. The frequency is formed under conditions of 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 surface electrodes contains (1) metal particles and (2) glass particles as essential components, and if necessary, (3) a resin binder, (4) other additives, and the like.

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 surface electrode containing a metal such as aluminum, silver or copper may be applied and dried to form the back surface electrode 20. At this time, in order to connect the solar cell elements 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 is calcined to form 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. The surface electrode 18 is composed of a bus bar electrode 30 and a finger electrode 32 that intersects the bus bar electrode 30. 2(A) is a plan view of a solar cell element having a configuration in which the surface electrode 18 is formed to include the bus bar electrode 30 and the finger electrode 32 crossing the bus bar electrode 30, as seen from the surface, 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.

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 composition of the type of diffusion layer can also produce a back contact solar cell element.

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 a structure in which a pn junction is formed by forming both an n-type diffusion portion and a p ⁺ -type diffusion portion on the back surface. Since the composition for forming an n-type diffusion layer of the present invention can form an n-type diffusion site only at a specific portion, it can be preferably applied to the manufacture of a back contact type solar cell element.

In addition, the entire contents disclosed in Japanese Patent Application No. 2010-100226 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, and are cited by reference. In this manual.

[Example]

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

[Example 1]

P ₂ O ₅ -CeO ₂ system glass having a particle shape of approximately spherical shape and an average particle diameter of 3.5 μm (P ₂ O ₅ : 39.6%, CeO ₂ : 10) using a mortar kneading machine %, BaO: 10.4%, MoO ₃ : 10%, ZnO: 30%) powder 20 g mixed with ethyl cellulose 0.3 g, 2-(2-butoxyethoxy)ethyl acetate 7 g and paste A composition for forming an n-type diffusion layer is formed.

The P ₂ O ₅ -CeO ₂ system glass powder was heated by a thermal analysis device (TG-DTA, DTG60H type, measurement conditions: heating rate 20 ° C / min, air flow rate 100 ml / min) manufactured by Shimadzu Corporation (share) As a result of the analysis, the softening temperature was 520 °C.

Further, the crystallization temperature is 1100 ° C or more, which exceeds the measurement range of the thermal analysis apparatus.

Further, the glass particle shape was observed and judged using a TM-1000 scanning electron microscope manufactured by Hitachi High-Technologies Co., Ltd. The average particle diameter of the glass was calculated using a LS 13 320 laser scattering diffraction particle size distribution measuring apparatus (measuring wavelength: 632 nm) manufactured by Beckman Coulter Co., Ltd.

Next, the prepared paste (the composition forming the n-type diffusion layer) 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. Then, heat diffusion treatment was performed for 10 minutes in an electric furnace set to 1000 ° C, and then, in order to remove the glass layer, the substrate was immersed in hydrofluoric acid for 5 minutes, and then washed with running water. Thereafter, drying is carried out.

The surface sheet resistance on the side coated with the composition forming the n-type diffusion layer was 45 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer. On the other hand, the sheet resistance including the portion of the back surface on which the composition for forming the n-type diffusion layer was not applied was too large to be measured, and it was judged that the n-type diffusion layer was not substantially formed. In addition, warpage of the substrate did not occur on the substrate. The evaluation results are shown in Table 1.

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

[Example 2]

An n-type diffusion layer was formed in the same manner as in Example 1 except that the thermal diffusion treatment time was set to 15 minutes. The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 30 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer.

On the other hand, the sheet resistance including the portion of the back surface on which the composition for forming the n-type diffusion layer was not applied was too large to be measured, and it was judged that the n-type diffusion layer was not substantially formed.

[Example 3]

An n-type diffusion layer was formed in the same manner as in Example 1 except that the thermal diffusion treatment time was set to 30 minutes. The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 17 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer.

On the other hand, the sheet resistance including the portion of the back surface on which the composition for forming the n-type diffusion layer was not applied was too large to be measured, and it was judged that the n-type diffusion layer was not substantially formed.

[Example 4]

The glass powder was replaced with a P ₂ O ₅ -ZnO system glass having a particle shape of a substantially spherical shape and an average particle diameter of 3.2 μm (P ₂ O ₅ : 40%, ZnO: 40%, CeO ₂ : 10%, MgO: 5). A composition for forming an n-type diffusion layer was prepared in the same manner as in Example 1 except that %, CaO: 5%), and the n-type diffusion layer was formed using the composition forming the n-type diffusion layer. Further, the softening temperature of the glass powder was 480 °C. Further, the crystallization temperature is 1100 ° C or more, which exceeds the measurement range of the thermal analysis apparatus.

The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 41 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer.

On the other hand, the sheet resistance including the portion of the back surface on which the composition for forming the n-type diffusion layer was not applied was too large to be measured, and it was judged that the n-type diffusion layer was not substantially formed.

[Example 5]

The glass powder was replaced with a P ₂ O ₅ -SiO ₂ system glass having a particle shape of a substantially spherical shape and an average particle diameter of 3.2 μm (P ₂ O ₅ : 30%, SiO ₂ : 50%, CeO ₂ : 10%, ZnO). A composition forming an n-type diffusion layer was prepared in the same manner as in Example 1 except that the composition of the n-type diffusion layer was formed, and an n-type diffusion layer was formed using the composition of the n-type diffusion layer. Further, the glass powder had a softening temperature of 610 °C. Further, the crystallization temperature is 1100 ° C or more, which exceeds the measurement range of the thermal analysis apparatus.

The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 48 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer.

On the other hand, the sheet resistance including the portion of the back surface on which the composition for forming the n-type diffusion layer was not applied was too large to be measured, and it was judged that the n-type diffusion layer was not substantially formed.

[Example 6]

An n-type diffusion layer was formed in the same manner as in Example 5 except that the heat diffusion treatment time was set to 30 minutes. The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 30 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer.

On the other hand, the sheet resistance including the portion of the back surface on which the composition for forming the n-type diffusion layer was not applied was too large to be measured, and it was judged that the n-type diffusion layer was not substantially formed.

[Example 7]

The glass powder was replaced with P ₂ O ₅ -PbO system glass (P ₂ O ₅ : 30%, PbO: 50%, ZnO: 20%) having a substantially spherical shape and an average particle diameter of 3.2 μm. A composition forming an n-type diffusion layer was prepared in the same manner as in Example 1, and the composition forming the n-type diffusion layer was used to form an n-type diffusion layer. Further, the softening temperature of the glass powder was 330 °C. Further, the crystallization temperature is 1100 ° C or more, which exceeds the measurement range of the thermal analysis apparatus.

The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 15 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer.

On the other hand, the sheet resistance including the portion of the back surface on which the composition for forming the n-type diffusion layer was not applied was too large to be measured, and it was judged that the n-type diffusion layer was not substantially formed.

[Example 8]

The glass powder was replaced with a P ₂ O ₅ -SiO ₂ system glass having a particle shape of a substantially spherical shape and an average particle diameter of 3.2 μm (P ₂ O ₅ : 40%, SiO ₂ : 10%, PbO: 30%, ZnO: A composition for forming an n-type diffusion layer was prepared in the same manner as in Example 1 except that 10%, CaO: 10%), and the n-type diffusion layer was formed using the composition forming the n-type diffusion layer. Further, the softening temperature of the glass powder was 360 °C. Further, the crystallization temperature is 1100 ° C or more, which exceeds the measurement range of the thermal analysis apparatus.

The sheet resistance of the surface on the side where the composition on which the n-type diffusion layer was formed was 21 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer.

On the other hand, the sheet resistance including the portion of the back surface on which the composition for forming the n-type diffusion layer was not applied was too large to be measured, and it was judged that the n-type diffusion layer was not substantially formed.

[Example 9]

The glass powder was replaced with a P ₂ O ₅ -SiO ₂ system glass having a particle shape of a substantially spherical shape and an average particle diameter of 3.2 μm (P ₂ O ₅ : 40%, SiO ₂ : 10%, PbO: 20%, ZnO: A composition for forming an n-type diffusion layer was prepared in the same manner as in Example 1 except that 20%, NaO: 10%), and the n-type diffusion layer was formed using the composition forming the n-type diffusion layer. Further, the softening temperature of the glass powder was 385 °C. Further, the crystallization temperature is 1100 ° C or more, which exceeds the measurement range of the thermal analysis apparatus.

The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 25 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer.

On the other hand, the sheet resistance including the portion of the back surface on which the composition for forming the n-type diffusion layer was not applied was too large to be measured, and it was judged that the n-type diffusion layer was not substantially formed.

[Example 10]

The glass powder was replaced with P ₂ O ₅ -ZnO system glass having a particle shape of substantially spherical shape and an average particle diameter of 3.2 μm (P ₂ O ₅ : 30%, ZnO: 40%, CaO: 20%, Al ₂ O ₃ (10%), except that a composition for forming an n-type diffusion layer was prepared in the same manner as in Example 1, and the composition for forming an n-type diffusion layer was used to form an n-type diffusion layer. Further, the softening temperature of the glass powder was 450 °C. Further, the crystallization temperature is 1100 ° C or more, which exceeds the measurement range of the thermal analysis apparatus.

The sheet resistance of the surface on the side on which the composition on which the n-type diffusion layer was formed was 36 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer.

On the other hand, the sheet resistance including the portion of the back surface on which the composition for forming the n-type diffusion layer was not applied was too large to be measured, and it was judged that the n-type diffusion layer was not substantially formed.

[Example 11]

The glass powder was replaced with a P ₂ O ₅ -SiO ₂ system glass having a particle shape of a substantially spherical shape and an average particle diameter of 3.2 μm (P ₂ O ₅ : 50%, SiO ₂ : 10%, ZnO: 30%, CaO: A composition for forming an n-type diffusion layer was prepared in the same manner as in Example 1 except that the thermal diffusion treatment time was set to 20 minutes, and the composition for forming the n-type diffusion layer was used to form. N-type diffusion layer. Further, the softening temperature of the glass powder was 610 °C. Further, the crystallization temperature is 1100 ° C or more, which exceeds the measurement range of the thermal analysis apparatus.

The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 40 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer.

On the other hand, the sheet resistance including the portion of the back surface on which the composition for forming the n-type diffusion layer was not applied was too large to be measured, and it was judged that the n-type diffusion layer was not substantially formed.

[Example 12]

The glass powder was replaced with a P ₂ O ₅ -SiO ₂ system glass (P ₂ O ₅ : 27%, SiO ₂ : 58%, CaO: 15%) having a particle shape of a substantially spherical shape and an average particle diameter of 3.2 μm. Except that the composition for forming the n-type diffusion layer was prepared in the same manner as in Example 1, and the composition for forming the n-type diffusion layer was used to form an n-type diffusion layer. Further, the softening temperature of the glass powder was 830 °C. Further, the crystallization temperature is 1100 ° C or more, which exceeds the measurement range of the thermal analysis apparatus.

The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 69 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer.

On the other hand, the sheet resistance including the portion of the back surface on which the composition for forming the n-type diffusion layer was not applied was too large to be measured, and it was judged that the n-type diffusion layer was not substantially formed.

[Example 13]

The glass powder was replaced with a P ₂ O ₅ —SiO ₂ system glass (P ₂ O ₅ : 30%, SiO ₂ : 60%, CaO: 10%) having a particle shape of a substantially spherical shape and an average particle diameter of 3.2 μm. Except that the composition for forming the n-type diffusion layer was prepared in the same manner as in Example 1, and the composition for forming the n-type diffusion layer was used to form an n-type diffusion layer. Further, the softening temperature of the glass powder was 875 °C. Further, the crystallization temperature is 1100 ° C or more, which exceeds the measurement range of the thermal analysis apparatus.

The sheet resistance of the surface on the side where the composition on which the n-type diffusion layer was formed was 71 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer.

On the other hand, the sheet resistance including the portion of the back surface on which the composition for forming the n-type diffusion layer was not applied was too large to be measured, and it was judged that the n-type diffusion layer was not substantially formed.

[Example 14]

The glass powder was replaced with a P ₂ O ₅ -SiO ₂ system glass having a particle shape of a substantially spherical shape and an average particle diameter of 3.2 μm (P ₂ O ₅ : 25%, SiO ₂ : 65%, CaO: 5%, Al _{2 )} A composition for forming an n-type diffusion layer was prepared in the same manner as in Example 1 except that O ₃ : 5%), and the composition for forming an n-type diffusion layer was used to form an n-type diffusion layer. Further, the softening temperature of the glass powder was 930 °C. Further, the crystallization temperature is 1100 ° C or more, which exceeds the measurement range of the thermal analysis apparatus.

The sheet resistance of the surface on the side on which the composition on which the n-type diffusion layer was formed was 83 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer.

On the other hand, the sheet resistance including the portion of the back surface on which the composition for forming the n-type diffusion layer was not applied was too large to be measured, and it was judged that the n-type diffusion layer was not substantially formed.

[Comparative Example 1]

20 g of ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ) powder was mixed with 3 g of ethyl cellulose and 7 g of 2-(2-butoxyethoxy)ethyl acetate using an automatic mortar mixing device. It is pasteified to form a composition (paste) which forms an n-type diffusion layer.

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

The sheet resistance of the surface coated with 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 formed on the back surface.

[Comparative Example 2]

A solution of 1 g of ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ) powder was mixed with 7 g of pure water, 0.7 g of polyvinyl alcohol, and 1.5 g of isopropyl alcohol to prepare a solution.

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

The sheet resistance of the surface on the side where the composition on which the n-type diffusion layer was formed 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 formed on the back surface.

[Comparative Example 3]

The glass powder was replaced with a P ₂ O ₅ —SiO ₂ system glass (P ₂ O ₅ : 10%, SiO ₂ : 20%, NaO: 70%) having a particle shape of a substantially spherical shape and an average particle diameter of 3.2 μm. Except that the composition for forming the n-type diffusion layer was prepared in the same manner as in Example 1, and the composition for forming the n-type diffusion layer was used to form an n-type diffusion layer. Further, the softening temperature of the glass powder was 230 °C.

The sheet resistance of the surface on the side on which the composition forming the n-type diffusion layer was applied was 61 Ω/□, and P (phosphorus) was diffused to form an n-type diffusion layer. However, the sheet resistance including the portion of the back surface which is not coated with the composition forming the n-type diffusion layer is 65 Ω/□, and the n-type diffusion layer is formed to an unnecessary portion, and the target n-type diffusion layer cannot be realized. Formation.

[Comparative Example 4]

The glass powder was replaced with a P ₂ O ₅ —SiO ₂ system glass (P ₂ O ₅ : 5%, SiO ₂ : 93%, NaO: 2%) having a particle shape of a substantially spherical shape and an average particle diameter of 3.2 μm. Except that the composition for forming the n-type diffusion layer was prepared in the same manner as in Example 1, and the composition for forming the n-type diffusion layer was used to form an n-type diffusion layer. Further, the softening temperature of the glass powder is 1100 ° C or more, which exceeds the measurement range of the thermal analysis apparatus.

The sheet resistance of the surface on the side on which the composition on which the n-type diffusion layer was formed was too large to be measured, and it was judged that the n-type diffusion layer was not substantially formed.

As described above, by using the composition for forming an n-type diffusion layer of the present invention, the n-type diffusion layer can be uniformly formed only at a specific portion.

While the present invention has been described in its preferred embodiments, the present invention is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

10. . . P-type semiconductor substrate / semiconductor substrate / 矽 / 矽 substrate

11. . . a composition layer forming an n-type diffusion layer / a composition forming an n-type diffusion layer

12. . . N-type diffusion layer

13. . . Composition layer/composition

14. . . P ⁺ type diffusion layer (high concentration electric field layer)

16. . . Anti-reflection film

18. . . Surface electrode

20. . . Back electrode/surface 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 observed from the surface.

Fig. 2(B) is a perspective view showing a part of Fig. 2(A) in an enlarged manner.

10. . . P-type semiconductor substrate / semiconductor substrate / 矽 / 矽 substrate

11. . . a composition layer forming an n-type diffusion layer / a composition forming an n-type diffusion layer

12. . . N-type diffusion layer

13. . . Composition layer/composition

14. . . P ⁺ type diffusion layer (high concentration electric field layer)

16. . . Anti-reflection film

18. . . Surface electrode

20. . . Back electrode/surface electrode

Claims (6)

A composition for forming an n-type diffusion layer, which is a composition for forming a method of forming an n-type diffusion layer, the method for forming the n-type diffusion layer, comprising: applying the composition for forming the n-type diffusion layer described above to a step of forming a composition layer forming an n-type diffusion layer on the semiconductor substrate; a step of heat-treating the semiconductor substrate on which the composition layer forming the n-type diffusion layer is formed, and forming an n-type diffusion layer on the semiconductor substrate; a step of removing the glass formed on the surface of the n-type diffusion layer, the composition forming the n-type diffusion layer comprising: a glass powder containing a donor element and having a softening temperature of 300 ° C to 950 ° C; and a dispersion medium. The composition for forming an n-type diffusion layer according to claim 1, 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 claim 1, wherein the glass powder containing the above-mentioned donor element comprises: at least one selected from the group consisting of P ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ a substance containing a donor element; and selected from the group consisting of SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO ₂ , CeO ₂ and MoO ₃ at least one glass component material. The composition for forming an n-type diffusion layer according to claim 1, wherein the glass powder has a crystallization temperature of 1050 ° C or higher. A method of manufacturing an n-type diffusion layer, comprising: A step of forming a composition for forming an n-type diffusion layer according to any one of claims 1 to 4; 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 an n-type diffusion layer according to any one of claims 1 to 4; and performing thermal diffusion treatment a step of forming an n-type diffusion layer; and a step of forming an electrode on the n-type diffusion layer formed.