JP5333564B2 - Method for manufacturing solar battery cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell manufacturing method which forms an n-type diffusion layer in a specific area without forming unnecessary n-type diffusion layers in a manufacturing process of solar cells using silicon substrates. <P>SOLUTION: A solar cell manufacturing method includes a process in which an n type diffusion layer formation composition containing glass powder including a donor element and a dispersion medium is applied to a part of a semiconductor substrate to form an n type diffusion layer formation composition layer and a heating process in which the semiconductor substrate, on which the n type diffusion layer formation composition layer is formed, is heated with an adequate temperature which allows the donor element to disperse from the glass powder to the semiconductor substrate so that an n type diffusion region is formed on the semiconductor substrate. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing a solar battery cell, and more particularly to a technique that enables an n-type diffusion layer to be formed in a specific portion of silicon as a semiconductor substrate.

The manufacturing process of the conventional silicon solar cell will be described.
First, a p-type silicon substrate having a textured structure formed on the light receiving surface is prepared so as to promote the light confinement effect, and then a donor element-containing compound such as phosphorus oxychloride (POCl ₃ ), nitrogen, oxygen The n-type diffusion layer is uniformly formed by performing several tens of minutes at 800 to 900 ° C. in the mixed gas atmosphere. In this conventional method, since phosphorus is diffused using a mixed gas, n-type diffusion layers are formed not only on the surface but also on the side surface and the back surface. Therefore, a side etching process for removing the side n-type diffusion layer is necessary. Further, the n-type diffusion layer on the back surface needs to be converted into a p ⁺ -type diffusion layer. An aluminum paste is applied on the n-type diffusion layer on the back surface, and the p ⁺ -type diffusion is performed from the n-type diffusion layer by the diffusion of aluminum. Was converted into a layer.

On the other hand, in the semiconductor manufacturing field, by applying a solution containing a phosphate such as phosphorus pentoxide (P ₂ O ₅ ) or ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ) as a donor element-containing compound. A method for forming an n-type diffusion layer has been proposed (see, for example, Patent Document 1). In addition, for forming a diffusion layer, a technique is also known in which a paste containing phosphorus as a donor element is applied on a silicon substrate surface as a diffusion source and thermally diffused to form a diffusion layer (see, for example, Patent Document 2). ). However, in these methods, since the donor element or a compound containing the same is scattered from the solution or paste as the diffusion source, the diffusion of phosphorus is caused by the side surface and the diffusion during the formation of the diffusion layer as in the gas phase reaction method using the mixed gas. An n-type diffusion layer is also formed on the back surface and in addition to the applied portion.

JP 2002-75894 A Japanese Patent No. 4073968

  As described above, in forming a n-type diffusion layer, in the gas phase reaction using phosphorus oxychloride, not only one side (usually the light receiving surface or the surface) that originally requires the n-type diffusion layer but also the other side An n-type diffusion layer is also formed on the surface (non-light-receiving surface or back surface) and side surfaces. In addition, even in a method in which a solution containing a compound containing phosphorus or a paste is applied and thermally diffused, an n-type diffusion layer is formed in addition to the surface as in the gas phase reaction method. Therefore, in order to have a pn junction structure as an element, it is necessary to perform etching on the side surface and convert the n-type diffusion layer to the p-type diffusion layer on the back surface. In general, an aluminum paste which is a Group 13 element is applied to the back surface and fired to convert the n-type diffusion layer into a p-type diffusion layer. Further, in the conventionally known method of applying a paste containing a donor element such as phosphorus as a diffusion source, the compound having the donor element is volatilized and gas is diffused and diffused in a region other than the region where diffusion is required. In particular, it is difficult to form a diffusion layer in a specific region.

The present invention has been made in view of the above-described conventional problems, and an n-type diffusion layer is formed in a specific portion without forming an unnecessary n-type diffusion layer in a manufacturing process of a solar battery cell using a silicon substrate. it is possible to form a further, when forming the diffusion layer to a specific area, the manufacturing method of the n-type n ⁺ layer to a specific part of the diffusion layer or the n ⁺⁺ layer capable of forming a solar cell, The issue is to provide

Means for solving the problems are as follows.
<1> Applying an n-type diffusion layer forming composition containing a glass powder containing a donor element and a dispersion medium to at least a part of a semiconductor substrate to form an n-type diffusion layer forming composition layer;
The semiconductor in which the n-type diffusion layer forming composition layer is formed at a temperature sufficient for the donor element to diffuse from the glass powder to the semiconductor substrate so that an n-type diffusion region is formed in the semiconductor substrate. A heating step for heating the substrate;
I have a,
The glass powder containing the donor element is composed of a donor element-containing substance, SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, and V ₂ O _{5. , SnO, ZrO 2, WO 3} , MoO 3, MnO, 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} The manufacturing method of a photovoltaic cell consisting of at least 1 sort (s) of glass component substance selected from these .

<2> The method for producing a solar battery cell according to <1>, wherein the n-type diffusion layer forming composition layer is dried before the heating step.

<3> The method for producing a solar battery cell according to <2>, wherein the drying is performed at a temperature within a range of 80 ° C to 300 ° C.

<4> The method for producing a solar cell according to any one of <1> to <3>, wherein the heating in the heating step is performed at a temperature within a range of 600 ° C to 1200 ° C.

<5> The method for producing a solar cell according to any one of <1> to <4>, wherein the heating in the heating step is performed in a time within a range of 1 minute to 600 minutes.

<6> The method for producing a solar cell according to any one of <1> to <5>, wherein the semiconductor substrate is a silicon substrate.

<7> The method for manufacturing a solar cell according to any one of <1> to <6>, wherein the glass layer formed on the surface of the semiconductor substrate is removed after the heating step.

<8> The glass powder containing the donor element according to any one of the above <1> to <7>, containing at least one donor element selected from P (phosphorus) and Sb (antimony). A method for producing a solar battery cell.

<9> The glass powder containing the donor element includes at least one donor element-containing material selected from P ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ , and SiO ₂ , K ₂ O, and Na ₂ O. And at least one glass component material selected from Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V ₂ O ₅ , SnO, ZrO ₂ and MoO ₃ , The manufacturing method of the photovoltaic cell of any one of said <1>-<8>.

<10> The method for producing a solar battery cell according to <9>, wherein the donor element-containing substance is contained at 29.6 mass% to 83 mass% in the glass powder containing the donor element.

<11> The method for producing a solar battery cell according to <9> or <10>, wherein the glass component substance is contained in an amount of 0.1% by mass to 95% by mass in the glass powder containing the donor element.

<12> The method for producing a solar cell according to any one of <9> to <11>, wherein the content of V ₂ O ₅ in the glass powder containing the donor element is 50% by mass or less.

<13> The method for producing a solar battery cell according to any one of <9> to <12>, wherein the glass component substance does not substantially contain V ₂ O ₅ .

The manufacturing method of the photovoltaic cell of any one of said <1>-<13> whose softening point of the glass powder containing the <14> above-mentioned donor element is the range of 200 to 1000 degreeC.

<15> The method for producing a solar battery cell according to any one of <1> to <14>, wherein the glass powder containing the donor element has a particle size of 100 μm or less.

<16> The method for producing a solar battery cell according to any one of <1> to <15>, wherein the dispersion medium includes a binder and a solvent.

<17> The method for producing a solar battery cell according to <16>, wherein the binder contains ethylcellulose.

<18> The method for producing a solar battery cell according to <16> or <17>, wherein the solvent is a solvent that volatilizes at a temperature in the range of 80 ° C to 300 ° C.

<19> In any one of the above items <1> to <18>, in the n-type diffusion layer forming composition, the glass powder containing the donor element is contained in an amount of 0.1% by mass to 95% by mass. Manufacturing method of solar cell.

<20> The solar cell according to any one of <1> to <19>, wherein the n-type diffusion layer forming composition further contains a metal that easily reacts with the glass powder containing the donor element. Production method.

  According to the present invention, an n-type diffusion layer can be formed in a specific region without forming an n-type diffusion layer in an unnecessary region in a manufacturing process of a solar battery cell using a silicon substrate.

It is sectional drawing which shows notionally an example of the manufacturing process of the photovoltaic cell of this invention. (A) is the top view which looked at the photovoltaic cell from the surface, (B) is the perspective view which expands and shows a part of (A).

First, the n-type diffusion layer forming composition of the present invention will be described, and then an n-type diffusion layer using the n-type diffusion layer forming composition and a method for producing a solar battery cell will be described.
In this specification, the term “process” is not limited to an independent process, and even if it cannot be clearly distinguished from other processes, the term “process” is used if the intended action of the process is achieved. included. In the present specification, “to” indicates a range including the numerical values described before and after the values as a minimum value and a maximum value, respectively.

The n-type diffusion layer forming composition of the present invention contains a glass powder containing at least a donor element (hereinafter sometimes simply referred to as “glass powder”) and a dispersion medium, and further considers coating properties and the like. Other additives may be contained as necessary.
Here, the n-type diffusion layer forming composition contains a glass powder containing a donor element, and is a material capable of forming an n-type diffusion layer by thermally diffusing this donor element after being applied to a silicon substrate. Say. By using an n-type diffusion layer forming composition containing a donor element in glass powder, an n-type diffusion layer is formed at a desired site, and an unnecessary n-type diffusion layer is not formed on the back surface or side surface.

Therefore, if the composition for forming an n-type diffusion layer of the present invention is applied, the side etching step that is essential in the gas phase reaction method that has been widely employed is not required, and the process is simplified. In addition, the step of converting the n-type diffusion layer formed on the back surface into the p ⁺ -type diffusion layer is not necessary. Therefore, the method for forming the p ⁺ -type diffusion layer on the back surface and the material, shape, and thickness of the back electrode are not limited, and the choice of manufacturing method, material, and shape to be applied is widened. Although details will be described later, generation of internal stress in the silicon substrate due to the thickness of the back electrode is suppressed, and warpage of the silicon substrate is also suppressed.

  In addition, the glass powder contained in the n type diffused layer formation composition of this invention fuse | melts by baking, and forms a glass layer on an n type diffused layer. However, a glass layer is formed on the n-type diffusion layer even in a conventional gas phase reaction method or a method of applying a phosphate-containing solution or paste, and thus the glass layer produced in the present invention is a conventional method. Similarly to the above, it can be removed by etching. Therefore, the n-type diffusion layer forming composition of the present invention does not generate unnecessary products and does not increase the number of steps as compared with the conventional method.

In addition, since the donor component in the glass powder is difficult to volatilize even during firing, it is suppressed that the n-type diffusion layer is formed not only on the surface but also on the back surface and side surfaces due to the generation of the volatilizing gas.
The reason for this is considered that the donor component is bonded to an element in the glass powder or is taken into the glass, so that it is difficult to volatilize.

  Thus, since the n-type diffusion layer forming composition of the present invention can form an n-type diffusion layer having a desired concentration at a desired site, a selective region having a high n-type dopant concentration is formed. It becomes possible to form. On the other hand, it is generally difficult to form a selective region having a high n-type dopant concentration by a gas phase reaction method, which is a general method of an n-type diffusion layer, or a method using a phosphate-containing solution. .

The glass powder containing the donor element according to the present invention will be described in detail.
A donor element is an element that can form an n-type diffusion layer by doping into a silicon substrate. As the donor element, a Group 15 element can be used, and examples thereof include P (phosphorus), Sb (antimony), Bi (bismuth), As (arsenic), and the like. From the viewpoints of safety, ease of vitrification, etc., P or Sb is preferred.

Examples of the donor element-containing material used for introducing the 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 , and P ₂ O ₃ It is preferable to use at least one selected from P ₂ O ₅ and Sb ₂ O ₃ .

Moreover, the glass powder containing a donor element can control a melting temperature, a softening point, a glass transition point, chemical durability, etc. by adjusting a component ratio as needed. Furthermore, it is preferable to contain the glass component substance described below.
Examples of glass component materials include SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V ₂ O ₅ , SnO, ZrO ₂ , WO ₃ , Examples include MoO ₃ , MnO, 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. SiO ₂ , K _{2 O, Na 2 O, Li} 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V 2 O 5, SnO, be at least one selected from ZrO _2, and MoO _{3 preferably, SiO 2, K 2 O,} Na 2 O, Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V 2 O 5, SnO, ZrO 2 and M It is more preferable to use at least one selected from O _3.

Specific examples of the glass powder containing a donor element include a system containing both the donor element-containing material and the glass component material, and a P ₂ O ₅ -SiO ₂ system (in order of donor element-containing material-glass component material). in described, the same applies _{hereinafter), P 2 O 5 -K 2} O _based, P ₂ O 5 -Na _{2 O-based,} P ₂ O 5 -Li ₂ O _system, P ₂ O 5 _-BaO-based, P 2 _{O 5} - _SrO-based, P ₂ O 5 _-CaO-based, P ₂ O 5 _-MgO-based, P ₂ O 5 -BeO _based, P ₂ O 5 _-ZnO-based, P ₂ O 5 -CdO _based, P ₂ O 5 -PbO system , including _P 2 _O 5 _-V 2 _{O 5 system,} P ₂ O 5 _-SnO-based, P ₂ O 5 -GeO _{2 system,} a _P 2 _{O 5} as a donor element-containing material of P ₂ O 5 -TeO ₂ system, etc. Instead of P ₂ O ₅ in a system containing P ₂ O ₅ , a donor element-containing material is used. And glass powder of a system containing Sb ₂ O ₃ .
Note that a glass powder containing two or more kinds of donor element-containing substances, such as a P ₂ O ₅ —Sb ₂ O ₃ system and a P ₂ O ₅ —As ₂ O ₃ system, may be used.
Although the composite glass containing two components was illustrated above, glass powder containing three or more components such as P ₂ O ₅ —SiO ₂ —V ₂ O ₅ and P ₂ O ₅ —SiO ₂ —CaO may be used.

  The content ratio of the glass component substance in the glass powder is preferably set as appropriate in consideration of the melting temperature, the softening point, the glass transition point, and the chemical durability, and is generally 0.1% by mass to 95% by mass. It is preferable that it is 0.5 mass% or more and 90 mass% or less.

Specifically, for example, as glass component materials, SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO ₂ , and MoO _The glass containing at least one selected from ₃ is preferable because the reaction product with the silicon substrate does not remain as a residue during the hydrofluoric acid treatment. Moreover, in the case of glass containing vanadium oxide V ₂ O ₅ as a glass component substance (for example, P ₂ O ₅ —V ₂ O ₅ glass), V ₂ O ₅ is used from the viewpoint of lowering the melting temperature and the softening point. The content ratio is preferably 1% by mass or more and 50% by mass or less, and more preferably 3% by mass or more and 40% by mass or less.

  The softening point of the glass powder is preferably 200 ° C. to 1000 ° C., more preferably 300 ° C. to 900 ° C., from the viewpoints of diffusibility during the 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, a scale shape, and the like. It is desirable to have a substantially spherical shape, a flat shape or a plate shape. The particle size of the glass powder is desirably 100 μm or less. When glass powder having a particle size of 100 μm or less is used, a smooth coating film is easily obtained. Furthermore, the particle size of the glass powder is more desirably 50 μm or less. The lower limit is not particularly limited, but is preferably 0.01 μm or more.
Here, the particle diameter of glass represents an average particle diameter, and can be measured by a laser scattering diffraction particle size distribution measuring apparatus or the like.

The glass powder containing a donor element is produced by the following procedure.
First, raw materials, for example, the donor element-containing material and the glass component material are weighed and filled in a crucible. Examples of the material for the crucible include platinum, platinum-rhodium, iridium, alumina, quartz, carbon, and the like, and are appropriately selected in consideration of the melting temperature, atmosphere, reactivity with the molten material, and the like.
Next, it heats with the temperature according to a glass composition with an electric furnace, and is set as a melt. At this time, it is desirable to stir the melt uniformly.
Subsequently, the obtained melt is poured onto a zirconia substrate, a carbon substrate or the like to vitrify the melt.
Finally, the glass is crushed into 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 n-type diffusion layer forming composition is determined in consideration of the coating property and the diffusibility of the donor element. In general, the content ratio of the glass powder in the n-type diffusion layer forming composition 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, The content is more preferably 1.5% by mass or more and 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 is a medium in which the glass powder is dispersed in the composition. Specifically, a binder or a solvent is employed as the dispersion medium.

  Examples of the binder include polyvinyl alcohol, polyacrylamides, polyvinylamides, polyvinylpyrrolidone, polyethylene oxides, polysulfonic acid, acrylamide alkylsulfonic acid, cellulose ethers, cellulose derivatives, carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose, gelatin, starch And starch derivatives, sodium alginates, xanthan, gua and gua derivatives, scleroglucan and scleroglucan derivatives, tragacanth and tragacanth derivatives, dextrin and dextrin derivatives, (meth) acrylic acid resins, (meth) acrylic acid ester resins (for example, , Alkyl (meth) acrylate resins, dimethylaminoethyl (meth) acrylate resins, etc.), butadiene resin , Styrene resin, or copolymers thereof, Additional be appropriately selected siloxane resin. These are used singly or in combination of two or more.

  The molecular weight of the binder is not particularly limited, and it is desirable to adjust appropriately in view of the desired viscosity of the composition.

  Examples of the solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-iso-propyl ketone, methyl-n-butyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone, methyl-n-hexyl ketone, Ketone solvents such as diethyl ketone, dipropyl ketone, di-iso-butyl ketone, trimethylnonanone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, γ-butyrolactone, γ-valerolactone , Diethyl ether, methyl ethyl ether, methyl-n-propyl ether, di-iso-propyl ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, dimethyldioxane, ethylene glycol dimethyl Ether, ethylene glycol diethyl ether, ethylene glycol di-n-propyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl mono-n-propyl ether, diethylene glycol methyl mono-n-butyl ether, Diethylene glycol di-n-propyl ether, diethylene glycol di-n-butyl ether, diethylene glycol methyl mono-n-hexyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol methyl mono-n- Butyl A Triethylene glycol di-n-butyl ether, triethylene glycol methyl mono-n-hexyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetradiethylene glycol methyl ethyl ether, tetraethylene glycol methyl mono-n-butyl ether, diethylene glycol Di-n-butyl ether, tetraethylene glycol methyl mono-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, di Propylene glycol dimethyl ether, dipropylene glycol Diethyl ether, dipropylene glycol methyl ethyl ether, dipropylene glycol methyl mono-n-butyl ether, dipropylene glycol di-n-propyl ether, dipropylene glycol di-n-butyl ether, dipropylene glycol methyl mono-n-hexyl ether, Tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, tripropylene glycol methyl ethyl ether, tripropylene glycol methyl mono-n-butyl ether, tripropylene glycol di-n-butyl ether, tripropylene glycol methyl mono-n-hexyl ether, tetrapropylene Glycol dimethyl ether, tetrapropylene glycol diethyl ether, tetradipropylene group Ether solvents such as recall methyl ethyl ether, tetrapropylene glycol methyl mono-n-butyl ether, dipropylene glycol di-n-butyl ether, tetrapropylene glycol methyl mono-n-hexyl ether, tetrapropylene glycol di-n-butyl ether, acetic acid Methyl, ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, 2- (2-butoxyethoxy) ethyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, nonyl acetate, methyl acetoacetate, ethyl acetoacetate, diethylene acetate Recall monomethyl ether, acetic acid diethylene glycol monoethyl ether, acetic acid diethylene glycol mono-n-butyl ether, acetic acid dipropylene glycol monomethyl ether, acetic acid dipropylene glycol monoethyl ether, diacetic acid glycol, acetic acid methoxytriglycol, acetic acid ethyl ethyl, propionic acid n- Ester solvents such as butyl, i-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, ethylene glycol methyl ether propionate, ethylene Glycol ethyl ether propionate, ethylene glycol methyl ether acetate, ethylene glycol ethyl ether acetate, diethylene glycol methyl ether acetate Ether acetates such as tate, 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 acetate, dipropylene glycol methyl ether acetate, dipropylene glycol ethyl ether acetate Solvent, acetonitrile, N-methylpyrrolidinone, N-ethylpyrrolidinone, N-propylpyrrolidinone, N-butylpyrrolidinone, N-hexylpyrrolidinone, N-cyclohexylpyrrolidinone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide Aprotic polar solvents such as methanol, ethanol N-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, sec-pentanol, t-pen Tanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, n- Decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, phenol, cyclohexanol, methylcyclohexanol, benzyl alcohol, ethylene glycol, 1, -Alcohol solvents such as propylene glycol, 1,3-butylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, ethylene 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 mono-n-hexyl ether, ethoxytriglycol, tetraethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether , Tripropylene Glycol monoether solvents such as coal monomethyl ether, terpene solvents such as α-terpinene, α-terpineol, myrcene, alloocimene, limonene, dipentene, α-pinene, β-pinene, terpineol, carvone, osimene, ferrandolene, water Is mentioned. These are used singly or in combination of two or more. When an n-type diffusion layer forming composition is used, α-terpineol, diethylene glycol mono-n-butyl ether, diethylene glycol acetate are used from the viewpoint of applicability to the substrate. Mono-n-butyl ether is preferable, and α-terpineol and diethylene glycol mono-n-butyl ether are preferable solvents.

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

Furthermore, the n-type diffusion layer forming composition may contain other additives. Examples of other additives include metals that easily react with the glass powder.
The n-type diffusion layer forming composition is applied on a semiconductor substrate and heat-treated at a high temperature to form an n-type diffusion layer. At that time, glass is formed on the surface. This glass is removed by dipping in an acid such as hydrofluoric acid, but some glass is difficult to remove depending on the type of glass. In that case, the glass can be easily removed after the acid cleaning by adding a metal such as Ag, Mn, Cu, Fe, Zn, or Si. Among these, it is preferable to use at least one selected from Ag, Si, Cu, Fe, Zn and Mn, more preferable to use at least one selected from Ag, Si and Zn. It is particularly preferred.

  The content ratio of the metal is desirably adjusted as appropriate depending on the type of glass and the type of the metal, and is generally preferably 0.01% by mass or more and 10% by mass or less with respect to the glass powder.

  Next, the manufacturing method of the n type diffused layer and photovoltaic cell of this invention is demonstrated, referring FIG. FIG. 1 is a schematic cross-sectional view conceptually showing an example of the manufacturing process of the solar battery cell of the present invention. In the subsequent drawings, common constituent elements are denoted by the same reference numerals.

In FIG. 1A, an alkaline solution is applied to a silicon substrate which is a p-type semiconductor substrate 10 to remove a damaged layer, and a texture structure is obtained by etching.
Specifically, the damaged layer on the silicon surface generated when slicing from the ingot is removed with 20% by mass caustic soda. Next, etching is performed with a mixed solution of 1% by mass caustic soda and 10% by mass isopropyl alcohol to form a texture structure (the description of the texture structure is omitted in the figure). In the solar battery cell, by forming a texture structure on the light receiving surface (front surface) side, a light confinement effect is promoted and high efficiency is achieved.

In FIG. 1B, the n-type diffusion layer forming composition layer 11 is formed by applying the n-type diffusion layer forming composition to the surface of the p-type semiconductor substrate 10, that is, the surface that becomes the light receiving surface. In the present invention, the coating method is not limited, and examples thereof include a printing method, a spin method, a brush coating, a spray method, a doctor blade method, a roll coater method, and an ink jet method.
Is not particularly limited as coated amount of the n-type diffusion layer forming composition, for example, be a 0.01g ^{/ m 2} ~100g ^/ m 2 as a glass powder content, 0.1 g ^/ m 2 to 10 g / M ² is preferable.

  Depending on the composition of the n-type diffusion layer forming composition, a drying step for volatilizing the solvent contained in the composition may be necessary after coating. In this case, drying is performed at a temperature of about 80 ° C. to 300 ° C. for 1 minute to 10 minutes when a hot plate is used, and about 10 minutes to 30 minutes when a dryer or the like is used. The drying conditions depend on the solvent composition of the n-type diffusion layer forming composition, 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 manufacturing method of the p ⁺ -type diffusion layer (high concentration electric field layer) 14 on the back surface is limited to a method by conversion from an n-type diffusion layer to a p-type diffusion layer with aluminum. Therefore, any conventionally known method can be adopted, and the options of the manufacturing method are expanded. Therefore, for example, the high-concentration electric field layer 14 can be formed by applying the composition 13 containing a Group 13 element such as B (boron).
As the composition 13 containing a Group 13 element such as B (boron), for example, a glass powder containing an acceptor element is used instead of a glass powder containing a donor element, and the same as the composition for forming an n-type diffusion layer. A p-type diffusion layer forming composition constituted as described above can be given. The acceptor element may be an element belonging to Group 13, and examples thereof include B (boron), Al (aluminum), and Ga (gallium). The glass powder containing acceptor element preferably comprises at least one selected from _{B 2 O 3, Al 2 O} 3 and _Ga 2 _{O 3.}
Furthermore, the method for applying the p-type diffusion layer forming composition to the back surface of the silicon substrate is the same as the method for applying the n-type diffusion layer forming composition described above on the silicon substrate.
The high-concentration electric field layer 14 can be formed on the back surface by subjecting the p-type diffusion layer forming composition applied to the back surface to a thermal diffusion treatment similar to the thermal diffusion treatment in the n-type diffusion layer forming composition described later. . The thermal diffusion treatment of the p-type diffusion layer forming composition is preferably performed simultaneously with the thermal diffusion treatment of the n-type diffusion layer forming composition.

Next, the semiconductor substrate 10 on which the n-type diffusion layer forming composition layer 11 is formed is subjected to thermal diffusion treatment at 600 ° C. to 1200 ° C. By this thermal diffusion treatment, as shown in FIG. 1C, the donor element diffuses into the semiconductor substrate, and the n-type diffusion layer 12 is formed. A known continuous furnace, batch furnace, or the like can be applied to the thermal diffusion treatment. Further, the furnace atmosphere during the thermal diffusion treatment can be appropriately adjusted to air, oxygen, nitrogen or the like.
The thermal diffusion treatment time can be appropriately selected according to the content of the donor element contained in the n-type diffusion layer forming composition. For example, it may be 1 minute to 60 minutes, and more preferably 2 minutes to 30 minutes.

  Since a glass layer (not shown) such as phosphate glass is formed on the surface of the formed n-type diffusion layer 12, this phosphate glass is removed by etching. As the etching, 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 can be applied.

In the method for forming an n-type diffusion layer of the present invention in which the n-type diffusion layer 12 is formed using the n-type diffusion layer forming composition 11 of the present invention shown in FIGS. Thus, the n-type diffusion layer 12 is formed, and no unnecessary n-type diffusion layer is formed on the back surface or the side surface.
Therefore, in the conventional method of forming an n-type diffusion layer by a gas phase reaction method, a side etching process for removing an unnecessary n-type diffusion layer formed on a side surface is essential. According to the manufacturing method of the invention, the side etching process is not required, and the process is simplified.

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. As this conversion method, a group 13 element is added to the n-type diffusion layer on the back surface. A method is adopted in which an aluminum paste is applied and baked to diffuse aluminum into the n-type diffusion layer and convert it into a p-type diffusion layer. In this method, in order to sufficiently convert to the p-type diffusion layer and to form a high concentration electric field layer of p ⁺ layer, an aluminum amount of a certain amount or more is required. Therefore, the aluminum layer is formed thick. There was a need. However, since the thermal expansion coefficient of aluminum is significantly different from that of silicon used as a substrate, a large internal stress is generated in the silicon substrate during the firing and cooling process, causing warpage of the silicon substrate. .
This internal stress has a problem that the crystal grain boundary is damaged and the power loss increases. In addition, the warp easily causes the cell to be damaged in the transportation of the solar battery cell in the module process and the connection with the copper wire called a tab wire. In recent years, the thickness of the silicon substrate is being reduced due to the improvement of the slice processing technique, and the cells tend to be 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 perform conversion from the n-type diffusion layer to the p-type diffusion layer, and the necessity of increasing the thickness of the aluminum layer is eliminated. . As a result, generation of internal stress and warpage in the silicon substrate can be suppressed. As a result, an increase in power loss and cell damage can be suppressed.

Further, when the manufacturing method of the present invention is used, the manufacturing method of the p ⁺ -type diffusion layer (high concentration electric field layer) 14 on the back surface is limited to a method by conversion from an n-type diffusion layer to a p-type diffusion layer with aluminum. Any method can be adopted without any problem, and the choice of manufacturing method is expanded.
For example, using a glass powder containing an acceptor element instead of a glass powder containing a donor element, a p-type diffusion layer forming composition configured in the same manner as the n-type diffusion layer forming composition is formed on the back surface (n The p ⁺ -type diffusion layer (high-concentration electric field layer) 14 is preferably formed on the back surface by applying to the surface opposite to the surface on which the mold diffusion layer forming composition is applied and baking.
As will be described later, the material used for the back surface electrode 20 is not limited to Group 13 aluminum, and for example, Ag (silver) or Cu (copper) can be applied. In addition, it can be formed thinner than the conventional one.

In FIG. 1 (4), an antireflection film 16 is formed on the n-type diffusion layer 12. The antireflection film 16 is formed by applying a known technique. For example, when the antireflection film 16 is a silicon nitride film, it is formed by a plasma CVD method using a mixed gas of SiH ₄ and NH ₃ as a raw material. At this time, hydrogen diffuses into the crystal, and orbits that do not contribute to the bonding of silicon atoms, that is, dangling bonds and hydrogen are combined to inactivate defects (hydrogen passivation).
More specifically, the mixed gas flow ratio NH ₃ / SiH ₄ is 0.05 to 1.0, the pressure in the reaction chamber is 0.1 Torr to 2 Torr, the temperature during film formation is 300 ° C. to 550 ° C., It is formed under the condition that the frequency for discharge is 100 kHz or more.

  In FIG. 1 (5), the surface electrode 18 is formed on the antireflection film 16 on the surface (light-receiving surface) by printing and drying the surface electrode metal paste by screen printing. The metal paste for a surface electrode contains (1) metal particles and (2) glass particles as essential components, and includes (3) a resin binder and (4) other additives as necessary.

  Next, the back electrode 20 is also formed on the high-concentration electric field layer 14 on the back surface. As described above, in the present invention, the material and forming method of the back electrode 20 are not particularly limited. For example, the back electrode 20 may be formed by applying and drying a back electrode paste containing a metal such as aluminum, silver, or copper. At this time, a silver paste for forming a silver electrode may be partially provided on the back surface for connection between cells in the module process.

  In FIG. 1 (6), an electrode is baked and a photovoltaic cell is completed. When firing at a temperature of 600 ° C. to 900 ° C. for several seconds to several minutes, the antireflection film 16 that is an insulating film is melted by the glass particles contained in the electrode metal paste on the surface side, and the silicon 10 surface is also partially melted. The metal particles (for example, silver particles) in the paste form a contact portion with the silicon substrate 10 and solidify. Thereby, the formed surface electrode 18 and the silicon substrate 10 are electrically connected. This is called fire-through.

  The shape of the surface electrode 18 will be described. The surface electrode 18 includes a bus bar electrode 30 and finger electrodes 32 intersecting with the bus bar electrode 30. FIG. 2A is a plan view of a solar cell in which the surface electrode 18 includes a bus bar electrode 30 and a finger electrode 32 intersecting the bus bar electrode 30 as viewed from the surface. FIG. 2B is an enlarged perspective view illustrating a part of FIG.

  Such a surface electrode 18 can be formed by means such as screen printing of the above-described metal paste, plating of an electrode material, or vapor deposition of an electrode material by electron beam heating in a high vacuum. The surface electrode 18 composed of the bus bar electrode 30 and the finger electrode 32 is generally used as an electrode on the light receiving surface side and is well known, and it is possible to apply known forming means for the bus bar electrode and finger electrode on the light receiving surface side. it can.

In the above description, the solar cell in which the n-type diffusion layer is formed on the front surface, the p ⁺ -type diffusion layer is formed on the back surface, and the front surface electrode and the back surface electrode are further provided on the respective layers has been described. If a layer forming composition is used, it is also possible to produce a back contact solar cell.
The back contact type solar battery cell has all electrodes provided on the back surface to increase the area of the light receiving surface. That is, in the back contact solar cell, it is necessary to form both the n-type diffusion region and the p ⁺ -type diffusion region on the back surface to form a pn junction structure. The n-type diffusion layer forming composition of the present invention can form an n-type diffusion site at a specific site, and thus can be suitably applied to the production of a back contact solar cell.

  Examples of the present invention will be described more specifically below, but the present invention is not limited to these examples. Unless otherwise stated, all chemicals used reagents. “%” Means “% by mass” unless otherwise specified.

[Example 1]
P ₂ O ₅ —V ₂ O ₅ glass (P ₂ O ₅ : 29.6%, V ₂ O ₅ : 10%) having a substantially spherical shape, an average particle diameter of 3.5 μm, and a softening point of 554 ° C. BaO: 10.4%, MoO ₃ : 10%, WO ₃ : 30%, K ₂ O: 10%) 20 g of powder, 0.3 g of ethyl cellulose, and 7 g of 2- (2-butoxyethoxy) ethyl acetate, An n-type diffusion layer forming composition was prepared by mixing using an automatic mortar kneader to make a paste.

  The glass particle shape was determined by observing with a TM-1000 scanning electron microscope manufactured by Hitachi High-Technologies Corporation. The average particle size of the glass was calculated using a LS 13 320 type laser scattering diffraction particle size distribution analyzer (measurement wavelength: 632 nm) manufactured by Beckman Coulter, Inc. The softening point of the glass was determined from a differential heat (DTA) curve using a DTG-60H type differential heat / thermogravimetric simultaneous measuring device manufactured by Shimadzu Corporation.

  Next, the prepared paste was applied to the surface of the p-type silicon substrate by screen printing and dried on a hot plate at 150 ° C. for 5 minutes to form a layer having a thickness of about 18 μm. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set at 1000 ° C., and then the substrate was immersed in hydrofluoric acid for 5 minutes in order to remove the glass layer, and washed with running water. There was some deposit on the surface, but it could be easily removed by rubbing with a waste cloth. Thereafter, drying was performed.

  The sheet resistance of the surface on which the n-type diffusion layer forming composition is applied is 186 Ω / □, and P (phosphorus) is diffused to form an n-type diffusion layer, at a level that functions sufficiently as a solar battery cell. there were. The sheet resistance on the back surface was 1000000 Ω / □ or more, which was not measurable, and it was determined that the n-type diffusion layer was not substantially formed.

  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 20 minutes. The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 70Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer.
The sheet resistance on the back surface was 1000000 Ω / □ or more, which was not measurable, and it was determined 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 30 minutes. The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 17Ω / □, and P (phosphorus) was diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance on the back surface was 1000000 Ω / □ or more, which was not measurable, and it was determined that the n-type diffusion layer was not substantially formed.

[Example 4]
P ₂ O ₅ —SnO glass (P ₂ O ₅ : 70%, SnO: 20%, SiO ₂ : 5) having a substantially spherical particle shape, an average particle diameter of 3.2 μm, and a softening point of 493 ° C. %, CaO: 5%), and an n-type diffusion layer was formed in the same manner as in Example 1 except that the furnace atmosphere during thermal diffusion was changed to nitrogen. The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 77Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance on the back surface was 1000000 Ω / □ or more, which was not measurable, and it was determined that the n-type diffusion layer was not substantially formed.

[Example 5]
The glass powder is made of P ₂ O ₅ —ZnO—SiO ₂ glass (P ₂ O ₅ : 60%, ZnO: 30%, SiO ₂ having a substantially spherical particle shape, an average particle diameter of 2.5 μm, and a softening point of 460 ° C. ₂ : 10%) The n-type diffusion layer was formed in the same manner as in Example 1 except that the n-type diffusion layer forming composition was used. The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 10Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance on the back surface was 1000000 Ω / □ or more, which was not measurable, and it was determined that the n-type diffusion layer was not substantially formed.

[Example 6]
P ₂ O ₅ —V ₂ O ₅ glass similar to Example 1 (P ₂ O ₅ : 29.6%, V ₂ O ₅ : 10%, BaO: 10.4%, MoO ₃ : 10%, WO ₃ : 30%, K ₂ O: 10%) 19.7 g of powder, 0.3 g of Ag, 0.3 g of ethyl cellulose, and 7 g of 2- (2-butoxyethoxy) ethyl acetate, an automatic mortar kneading apparatus The mixture was used to form a paste to prepare an n-type diffusion layer forming composition. Thereafter, the same operation as in Example 2 was performed.
As a result, the substrate after cleaning had no glass deposits and was easily removed. Further, the sheet resistance on the front surface was 70Ω / □ as in Example 2, and it was determined that the n-type diffusion layer was not substantially formed on the back surface.

[Example 7]
An n-type glass powder made of P ₂ O ₅ —ZnO glass (P ₂ O ₅ : 65%, ZnO: 35%) having a substantially spherical particle shape, an average particle diameter of 1.3 μm, and a softening point of 435 ° C. An n-type diffusion layer was formed in the same manner as in Example 1 except that the diffusion layer forming composition was used.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 18Ω / □, and P was diffused to form an n-type diffusion layer. On the other hand, the sheet resistance on the back surface cannot be measured, and it was determined that the n-type diffusion layer was not substantially formed.

[Example 8]
The glass powder has a substantially spherical particle shape, an average particle diameter of 2.9 μm, and a P ₂ O ₅ —ZnO—Al ₂ O ₃ glass (P ₂ O ₅ : 61%, ZnO: 35%) having a softening point of 423 ° C. , Al ₂ O ₃ : 4%) The n-type diffusion layer was formed in the same manner as in Example 1 except that the n-type diffusion layer forming composition was used.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 21Ω / □, and P was diffused to form an n-type layer. On the other hand, the sheet resistance on the back surface cannot be measured, and it was determined that the n-type diffusion layer was not substantially formed.

[Example 9]
The glass powder is P ₂ O ₅ —ZnO—Y ₂ O ₃ glass (P ₂ O ₅ : 61%, ZnO: 35%) having a substantially spherical particle shape, an average particle diameter of 2.1 μm, and a softening point of 430 ° C. , Y ₂ O ₃ : 4%) The n-type diffusion layer was formed in the same manner as in Example 1 except that the n-type diffusion layer forming composition was used.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 25Ω / □, and P was diffused to form an n-type diffusion layer. On the other hand, the sheet resistance on the back surface cannot be measured, and it was determined that the n-type diffusion layer was not substantially formed.

[Example 10]
The glass powder is made of P ₂ O ₅ —ZnO—K ₂ O-based glass (P ₂ O ₅ : 61%, ZnO: 35%) having a substantially spherical particle shape, an average particle diameter of 2.4 μm, and a softening point of 395 ° C. N-type diffusion layer formation was performed in the same manner as in Example 1 except that the n-type diffusion layer forming composition was used (K ₂ O: 4%).
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 19Ω / □, and P was diffused to form an n-type diffusion layer. On the other hand, the sheet resistance on the back surface cannot be measured, and it was determined that the n-type diffusion layer was not substantially formed.

[Example 11]
The glass powder is made of P ₂ O ₅ —ZnO—K ₂ O—Na ₂ O glass (P ₂ O ₅ : 62%, ZnO) having a substantially spherical particle shape, an average particle diameter of 3.0 μm, and a softening point of 406 ° C. : 35%, K ₂ O: 2%, Na ₂ O: 1%) The n-type diffusion layer was formed in the same manner as in Example 1 except that the n-type diffusion layer forming composition was used.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 21Ω / □, and P was diffused to form an n-type diffusion layer. On the other hand, the sheet resistance on the back surface cannot be measured, and it was determined that the n-type diffusion layer was not substantially formed.

[Example 12]
An n-type glass powder having a substantially spherical particle shape, an average particle diameter of 2.8 μm, and a P ₂ O ₅ —CaO glass (P ₂ O ₅ : 83%, CaO: 17%) having a softening point of 470 ° C. An n-type diffusion layer was formed in the same manner as in Example 1 except that the diffusion layer forming composition was used.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 14Ω / □, and P was diffused to form an n-type diffusion layer. On the other hand, the sheet resistance on the back surface cannot be measured, and it was determined that the n-type diffusion layer was not substantially formed.

[Example 13]
The n-type diffusion layer is the same as in Example 7 except that the silicon substrate (5 cm × 5 cm, the same in the following examples) is coated on the half surface instead of the entire surface, and the set temperature of the electric furnace is set to 950 ° C. Formation was performed.
The sheet resistance of the surface where the n-type diffusion layer forming composition was applied was 38Ω / □, and P was diffused to form an n-type diffusion layer. On the other hand, the sheet resistance of the surface of the portion where the n-type diffusion layer forming composition is not applied is not measurable, the n-type diffusion layer is not formed, and is selected as the portion where the n-type diffusion layer forming composition is applied. Thus, an n-type diffusion layer was formed. Further, the sheet resistance on the back surface was not measurable, and it was determined that the n-type diffusion layer was not substantially formed.

[Example 14]
An n-type diffusion layer was formed in the same manner as in Example 8 except that the coating was applied to the half surface instead of the entire surface of the silicon substrate and that the set temperature of the electric furnace was set to 950 ° C.
The sheet resistance of the surface of the portion where the n-type diffusion layer forming composition was applied was 45Ω / □, and P was diffused to form an n-type diffusion layer. On the other hand, the sheet resistance of the surface of the portion where the n-type diffusion layer forming composition is not applied is not measurable, the n-type diffusion layer is not formed, and is selected as the portion where the n-type diffusion layer forming composition is applied. Thus, an n-type diffusion layer was formed. Further, the sheet resistance on the back surface was not measurable, and it was determined that the n-type diffusion layer was not substantially formed.

[Example 15]
An n-type diffusion layer was formed in the same manner as in Example 9 except that the coating was applied to the half surface instead of the entire surface of the silicon substrate, and the temperature setting of the electric furnace was set to 950 ° C.
The sheet resistance of the surface of the portion where the n-type diffusion layer forming composition was applied was 35Ω / □, and P was diffused to form an n-type diffusion layer. On the other hand, the sheet resistance of the surface of the portion where the n-type diffusion layer forming composition is not applied is not measurable, the n-type diffusion layer is not formed, and is selected as the portion where the n-type diffusion layer forming composition is applied. Thus, an n-type diffusion layer was formed. Further, the sheet resistance on the back surface was not measurable, and it was determined that the n-type diffusion layer was not substantially formed.

[Example 16]
An n-type diffusion layer was formed in the same manner as in Example 10 except that the coating was performed on the half surface of the silicon substrate instead of the entire surface and that the electric furnace was set at a temperature of 950 ° C.
The sheet resistance of the surface where the n-type diffusion layer forming composition was applied was 42 Ω / □, and P was diffused to form an n-type diffusion layer. On the other hand, the sheet resistance of the surface of the portion where the n-type diffusion layer forming composition is not applied is not measurable, the n-type diffusion layer is not formed, and is selected as the portion where the n-type diffusion layer forming composition is applied. Thus, an n-type diffusion layer was formed. Further, the sheet resistance on the back surface was not measurable, and it was determined that the n-type diffusion layer was not substantially formed.

[Example 17]
An n-type diffusion layer was formed in the same manner as in Example 11 except that the coating was performed on the half surface of the silicon substrate instead of the entire surface, and the temperature set for the electric furnace was 950 ° C.
The sheet resistance of the surface where the n-type diffusion layer forming composition was applied was 50 Ω / □, and P diffused to form an n-type diffusion layer. On the other hand, the sheet resistance of the surface of the portion where the n-type diffusion layer forming composition is not applied is not measurable, the n-type diffusion layer is not formed, and is selected as the portion where the n-type diffusion layer forming composition is applied. Thus, an n-type diffusion layer was formed. Further, the sheet resistance on the back surface was not measurable, and it was determined that the n-type diffusion layer was not substantially formed.

[Example 18]
An n-type diffusion layer was formed in the same manner as in Example 12 except that the coating was performed on the half surface of the silicon substrate instead of the entire surface and that the set temperature of the electric furnace was 950 ° C.
The sheet resistance of the surface where the n-type diffusion layer forming composition was applied was 38Ω / □, and P was diffused to form an n-type diffusion layer. On the other hand, the sheet resistance of the surface of the portion where the n-type diffusion layer forming composition is not applied is not measurable, the n-type diffusion layer is not formed, and is selected as the portion where the n-type diffusion layer forming composition is applied. Thus, an n-type diffusion layer was formed. Further, the sheet resistance on the back surface was not measurable, and it was determined that the n-type diffusion layer was not substantially formed.

[Example 19]
A glass powder having a substantially spherical particle shape, an average particle diameter of 1.7 μm, and a P ₂ O ₅ —SiO ₂ —CaO-based glass having a softening point of 756 ° C. (P ₂ O ₅ : 30%, SiO2: 60%, CaO) 10%), and n-type diffusion layer forming composition obtained by mixing 10 g of this glass powder, 4 g of ethyl cellulose, and 86 g of α-terpineol in the same manner was used in the same manner as in Example 1 Diffusion layer formation was performed. The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 30Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance on the back surface was 1000000 Ω / □ or more, which was not measurable, and it was determined 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, 3 g of ethyl cellulose, and 7 g of 2- (2-butoxyethoxy) ethyl acetate were mixed and pasted to prepare an n-type diffusion layer forming composition. .
Next, the prepared paste was applied to the surface of the p-type silicon substrate by screen printing and dried on a hot plate at 150 ° C. for 5 minutes. Subsequently, a thermal diffusion treatment was performed for 10 minutes in an electric furnace set at 1000 ° C., and then the substrate was immersed in hydrofluoric acid for 5 minutes to remove the glass layer, washed with running water, and dried.

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

[Comparative Example 2]
An n-type diffusion layer forming composition was prepared by mixing 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. Prepared.
Next, the prepared solution was applied to the surface of the p-type silicon substrate by a spin coater (2000 rpm, 30 sec) and dried on a hot plate at 150 ° C. for 5 minutes. Subsequently, a thermal diffusion treatment was performed for 10 minutes in an electric furnace set at 1000 ° C., and then the substrate was immersed in hydrofluoric acid for 5 minutes to remove the glass layer, washed with running water, and dried.

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

[Comparative Example 3]
1 g of phosphoric acid, 9 g of SiO ₂ powder, 3 g of polyvinyl alcohol, and 90 g of pure water were mixed to form a paste to prepare an n-type diffusion layer forming composition.
Next, the prepared paste was applied to the surface of the p-type silicon substrate by screen printing and dried on a hot plate at 150 ° C. for 5 minutes. Subsequently, a thermal diffusion treatment was performed for 10 minutes in an electric furnace set at 1000 ° C., and then the substrate was immersed in hydrofluoric acid for 5 minutes to remove the glass layer, washed with running water, and dried.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 30Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer. However, the sheet resistance on the back surface was 60Ω / □, and an n-type diffusion layer was also formed on the back surface.

10 p-type semiconductor substrate 12 n-type diffusion layer 14 high-concentration electric field layer 16 antireflection film 18 surface electrode 20 back electrode (electrode layer)
30 Busbar electrode 32 Finger electrode

Claims (20)

Applying an n-type diffusion layer forming composition containing a glass powder containing a donor element and a dispersion medium to at least a part of a semiconductor substrate to form an n-type diffusion layer forming composition layer;
The semiconductor in which the n-type diffusion layer forming composition layer is formed at a temperature sufficient for the donor element to diffuse from the glass powder to the semiconductor substrate so that an n-type diffusion region is formed in the semiconductor substrate. A heating step for heating the substrate;
I have a,
The glass powder containing the donor element is composed of a donor element-containing substance, SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, and V ₂ O _{5. , SnO, ZrO 2, WO 3} , MoO 3, MnO, 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} The manufacturing method of a photovoltaic cell consisting of at least 1 sort (s) of glass component substance selected from these .   The manufacturing method of the photovoltaic cell of Claim 1 with which the said n type diffused layer formation composition layer is dried before the said heating process.   The manufacturing method of the photovoltaic cell of Claim 2 with which the said drying is performed at the temperature within the range of 80 to 300 degreeC.   The manufacturing method of the photovoltaic cell of any one of Claims 1-3 with which the heating in the said heating process is performed at the temperature within the range of 600 to 1200 degreeC.   The manufacturing method of the photovoltaic cell of any one of Claims 1-4 with which the heating in the said heating process is performed in the time within the range of 1 minute-600 minutes.   The manufacturing method of the photovoltaic cell of any one of Claims 1-5 whose said semiconductor substrate is a silicon substrate.   The manufacturing method of the photovoltaic cell of any one of Claims 1-6 which removes the glass layer formed in the surface of the said semiconductor substrate after the said heating process.   The photovoltaic cell of any one of Claims 1-7 in which the glass powder containing the said donor element contains the at least 1 sort (s) of donor element selected from P (phosphorus) and Sb (antimony). Production method. The glass powder containing the donor element includes at least one donor element-containing material selected from P ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ , SiO ₂ , K ₂ O, Na ₂ O, Li _2. And at least one glass component material selected from O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V ₂ O ₅ , SnO, ZrO ₂ and MoO _3. The manufacturing method of the photovoltaic cell of any one of Claims 8.   The manufacturing method of the photovoltaic cell of Claim 9 with which the said donor element containing material is contained by 29.6 mass%-83 mass% in the glass powder containing the said donor element.   The manufacturing method of the photovoltaic cell of Claim 9 or Claim 10 with which the said glass component substance is contained by 0.1 mass%-95 mass% in the glass powder containing the said donor element. The content of V ₂ O ₅ in the glass powder containing donor element is less than 50 wt%, the method for manufacturing a solar battery cell according to any one of claims 9 to 11. The glass component material is substantially free of V ₂ O _5, the method for manufacturing a solar battery cell according to any one of claims 9 to 12.   The manufacturing method of the photovoltaic cell of any one of Claims 1-13 whose softening point of the glass powder containing the said donor element is the range of 200 to 1000 degreeC.   The manufacturing method of the photovoltaic cell of any one of Claims 1-14 whose particle size of the glass powder containing the said donor element is 100 micrometers or less.   The manufacturing method of the photovoltaic cell of any one of Claims 1-15 in which the said dispersion medium contains a binder and a solvent.   The manufacturing method of the photovoltaic cell of Claim 16 in which the said binder contains ethylcellulose.   The method for producing a solar battery cell according to claim 16 or 17, wherein the solvent is a solvent that volatilizes at a temperature in the range of 80C to 300C.   The photovoltaic cell of any one of Claims 1-18 in which the glass powder containing the said donor element is contained by 0.1 mass%-95 mass% in the said n type diffused layer formation composition. Manufacturing method. The n-type diffusion layer forming composition further contains a reactive metal easily and glass powder containing the donor element, producing how a solar cell according to any one of claims 1 to 19.