JP2012129418A - Composition for forming n-type diffusion layer, method for manufacturing n-type diffusion layer and method for manufacturing solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for forming an n-type diffusion layer which can form an n-type diffusion layer while suppressing occurrence of striation, and to provide a method for manufacturing an n-type diffusion layer and a method for manufacturing a solar cell.SOLUTION: The composition for forming the n-type diffusion layer contains glass powder including a donor element, a silicon-containing substance and a dispersion medium. The n-type diffusion layer and the solar cell having the n-type diffusion layer are manufactured by applying the composition for forming the n-type diffusion layer onto a semiconductor substrate and subjecting the applied substrate to heat diffusion treatment.

Description

  The present invention relates to an n-type diffusion layer forming composition for solar cells, a method for producing n-type diffusion layers, and a method for producing solar cells, and more specifically, a specific portion of crystalline silicon that is a semiconductor substrate. The present invention relates to a technique that makes it possible to form an n-type diffusion layer.

The manufacturing process of the conventional crystalline silicon solar cell will be described.
First, a p-type silicon substrate having a textured structure is prepared so as to promote the light confinement effect and achieve high efficiency, and then 800 to 900 ° C. in a mixed gas atmosphere of phosphorus oxychloride (POCl ₃ ), nitrogen and oxygen. The n-type diffusion layer is uniformly formed by performing several tens of minutes. 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, an n-type diffusion layer is formed 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 ). A method has been proposed (see, for example, Patent Document 1). However, since this method uses a solution, as in the gas phase reaction method using the above mixed gas, the diffusion of phosphorus extends to the side surface and back surface, and n-type diffusion layers are formed not only on the surface but also on the side surface and back surface. Is done.
In addition, a technique is also known in which a diffusion layer is formed by applying a paste containing a donor element such as phosphorus as a diffusion source and thermally diffusing to form a diffusion layer (see, for example, Patent Document 2).

JP 2002-75894 A Japanese Patent No. 4073968

As described above, when forming the n-type diffusion layer, in the gas phase reaction using phosphorus oxychloride, not only one surface (usually the light receiving surface, the surface) that originally requires the n-type diffusion layer but also the other surface ( An n-type diffusion layer is also formed on the non-light-receiving surface, back surface) and side surfaces. Further, even in the method of applying a solution containing phosphate and thermally diffusing, an n-type diffusion layer is formed on the surface other than 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 diffuses in a region other than the region where diffusion is required. There is a drawback that it is difficult to form a diffusion layer in a specific region called a selective emitter. In addition, a stripe pattern having a height difference of several hundreds of degrees called striations may occur on the substrate during the n-type diffusion layer forming process.

  The present invention has been made in view of the above-described conventional problems, and an n-type diffusion layer forming composition and an n-type diffusion layer capable of forming an n-type diffusion layer while suppressing the occurrence of striations It is an object of the present invention to provide a manufacturing method and a solar cell manufacturing method.

Means for solving the problems are as follows.
<1> An n-type diffusion layer forming composition containing a glass powder containing a donor element, a silicon-containing substance, and a dispersion medium.

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

<3> The n-type diffusion layer forming composition according to <1> or <2>, wherein the silicon-containing substance is silicon oxide.

<4> 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 n-type diffusion layer forming composition according to any one of <1> to <3>.

<5> The n-type diffusion layer forming composition according to any one of <1> to <4>, further including an organic binder.

<6> Any one of <1> to <5>, containing 1% by mass or more and 80% by mass or less of the glass powder and 0.1% by mass or more and 30% by mass or less of the silicon-containing substance. An n-type diffusion layer forming composition as described in 1. above.

<7> The n-type diffusion layer forming composition according to any one of <1> to <6>, wherein the glass powder has a volume average particle size of 0.1 μm or more and 10 μm or less.

<8> An n-type diffusion layer comprising a step of applying the n-type diffusion layer forming composition according to any one of <1> to <7> on a semiconductor substrate and a step of performing a thermal diffusion treatment. Manufacturing method.

<9> A step of applying the n-type diffusion layer forming composition according to any one of <1> to <7> on a semiconductor substrate and a thermal diffusion treatment to form an n-type diffusion layer The manufacturing method of the photovoltaic cell which has the process to form and the process of forming an electrode on the formed n type diffused layer.

  ADVANTAGE OF THE INVENTION According to this invention, provision of the n type diffused layer formation composition which can form an n type diffused layer, suppressing the generation | occurrence | production of a striation, the manufacturing method of an n type diffused layer, and the manufacturing method of a photovoltaic cell It becomes possible to do.

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). It is sectional drawing which shows notionally an example of the manufacturing process of the photovoltaic cell of this invention.

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 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 composition for forming an n-type diffusion layer of the present invention includes at least one glass powder containing at least a donor element (hereinafter sometimes simply referred to as “glass powder”), at least one substrate erosion inhibitor, and a dispersion. In addition, other additives may be contained as necessary in consideration of coating properties.
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 the n-type diffusion layer forming composition containing the donor element in the glass powder, the n-type diffusion layer is formed only at a desired site, and an unnecessary n-type diffusion layer is not formed on the back surface or the side surface.

Therefore, if the composition for forming an n-type diffusion layer of the present invention is applied, the side etching step 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.

As described above, the n-type diffusion layer forming composition of the present invention can form an n-type diffusion layer having a desired concentration only at a desired site, and therefore a selective region having a high n-type dopant concentration. Can be formed. In particular, using the n-type diffusion layer forming composition of the present invention, a selective region having a high n-type dopant concentration (hereinafter, this region may be referred to as “selective emitter”) is formed immediately below the electrode. Te with the n ⁺ layer and n ⁺⁺ layer, it becomes possible to reduce the contact resistance between the n-type diffusion layer and the electrode.
Since the selective emitter increases the n-type dopant concentration only in the selective region, the selective emitter is formed by a gas phase reaction method, which is a general method of the n-type diffusion layer, or a method using a phosphate-containing solution. It is difficult to form.

  Furthermore, in addition to the glass powder containing the donor element, by containing a silicon-containing substance, the n-type diffusion is suppressed while suppressing the occurrence of striation due to the erosion of the substrate that may occur during the n-type diffusion layer forming process. A layer can be formed efficiently. Furthermore, a uniform n-type diffusion layer can be formed on the substrate. In addition, the flatness of the substrate after etching after forming the n-type diffusion layer can be improved, and the occurrence of surface roughness of the substrate can be suppressed.

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), 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 , CsO ₂ , TiO ₂ , ZrO ₂ , GeO ₂ , TeO _2, and Lu ₂ O _{3. 2, K 2 O, Na 2} O, Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V 2 O 5, SnO, at least one selected from ZrO _2, and MoO ₃ Is preferably used.

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 such as 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 glass powder 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 O, BaO, _{SrO, CaO, MgO, BeO,} ZnO, PbO, CdO, V 2 O 5, SnO, ZrO 2, MoO 3, GeO 2, Y 2 O 3, at least one glass component is selected from CsO ₂ and TiO ₂ And a donor element-containing material that is P ₂ O ₅ and at least one glass component material selected from SiO ₂ , ZnO, CaO, Na ₂ O, Li ₂ O and BaO It is more preferable to contain. Thereby, the sheet resistance of the n-type diffusion layer to be formed can be further reduced.

  The content ratio of the glass component substance in the glass powder is preferably set as appropriate in consideration of the melting temperature, softening point, glass transition point, and chemical durability, and is generally 0.01% by mass to 80% by mass. It is preferable that it is 0.1 mass% or more and 50 mass% or less. An n-type diffused layer can be efficiently formed as it is 0.01 mass% or more. Moreover, formation of the n-type diffused layer in the part which has not provided the n-type diffused layer formation composition as it is 80 mass% or less can be suppressed.

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. From the viewpoint of the application property to the substrate and the uniform diffusibility when it is an n-type diffusion layer forming composition, 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. In addition, although a minimum in particular is not restrict | limited, It is preferable that it is 0.01 micrometer or more, and it is more preferable that it is 0.1 micrometer or more.
Here, the particle diameter of glass represents a volume 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 uniform melt. At this time, it is desirable to stir the melt uniformly. Subsequently, the melt that has become uniform 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 applicability, diffusibility of the donor element, and the like. 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, It is more preferably 1% by mass or more and 80% by mass or less, further preferably 2% by mass or more and 80% by mass or less, and particularly preferably 5% by mass or more and 20% by mass or less.
An n-type diffusion layer can be sufficiently formed when the content of the glass powder is 0.1% by mass or more. When it is 95% by mass or less, the dispersibility of the glass powder in the n-type diffusion layer forming composition is improved, and the coating property to the substrate is improved.

The n-type diffusion layer forming composition contains at least one silicon-containing material. By including the silicon-containing substance, it plays a role of suppressing the reaction between the substrate and the substance contained in the n-type diffusion layer forming composition during thermal diffusion (hereinafter also referred to as substrate erosion suppression). The composition of the silicon-containing substance is not limited as long as it shows an effect of suppressing substrate erosion.
Examples of the silicon-containing substance include silicon oxide, silane resin, and silicon alkoxide. Among these, from the viewpoint of suppressing substrate erosion, silicon oxide is preferable, and SiO ₂ is more preferable.
The silicon-containing material is preferably physically mixed as an independent material rather than as part of the glass component in the glass powder containing the donor element.

The silicon oxide is generally represented by SiOx. The range of x is preferably 1 ≦ x ≦ 2, for example, and more preferably x = 2.
SiO ₂ as the silicon-containing material may be a crystalline SiO _2, it may be a SiO ₂ of amorphous, or may be a glass powder containing SiO _2.

The silicon-containing material preferably does not contain a donor element as a main component. By not including the donor element as a main component, the silicon-containing substance itself can be prevented from reacting with the substrate.
“Not contained as a main component” means that the content of the donor element in the silicon-containing substance is 1% by mass or less, and preferably 0.1% by mass or less.

  Further, the silicon-containing substance may be removed in any of the steps of forming the n-type diffusion layer using the n-type diffusion layer forming composition, and for example, a composition that dissolves in an acid or the like is preferable. Even if the solar cell is formed by forming an electrode while the silicon-containing substance is present on the substrate, there is no problem.

  The shape of the silicon-containing substance is not particularly limited, and for example, a substantially spherical shape, a flat shape, a block shape, a plate shape, a scale shape, and the like can be exemplified as a particle shape.

When the silicon-containing substance is in the form of particles, the volume average particle diameter is preferably 20 μm or less, more preferably 5 μm or less. When a silicon-containing material having a volume average particle diameter of 20 μm or less is used, it is easy to mix uniformly with glass powder, and productivity is improved.
The lower limit of the volume average particle diameter is not particularly limited, but is preferably 0.01 μm or more. If it is 0.01 μm or more, the dispersibility in the paste becomes better.

  The silicon-containing substance is preferably added in an amount of 0.05 to 40% by mass, more preferably 0.1 to 30% by mass, and more preferably 1 to 30% by mass in the n-type diffusion layer forming composition. More preferably, it is more preferable to add 2 to 20% by mass. By being 0.05 mass% or more, a sufficient substrate erosion suppressing effect can be obtained. Moreover, an n-type diffused layer can be more effectively formed as it is 40 mass% or less.

  Moreover, it is preferable to add 1-200 mass% of silicon-containing substances with respect to glass powder, and it is still more preferable to add 20-100 mass%. By being 1% by mass or more, a sufficient substrate erosion suppressing effect can be obtained. Moreover, an n type diffused layer can be more effectively formed as it is 200 mass% or less.

The n-type diffusion layer forming composition preferably contains at least one oxidation accelerator. The composition of the oxidation accelerator is not particularly limited as long as it plays a role of functioning as an oxidation catalyst, and may be either organic or inorganic.
By including an oxidation accelerator, when an n-type diffusion layer is formed using an n-type diffusion layer forming composition, the generation of an organic residue component can be effectively suppressed.

Examples of the oxidation accelerator include hydrogen peroxide, CuO, Co ₃ O ₄ , NiO, Fe ₂ O ₃ , CdO, TiO ₂ , V ₂ O ₅ , SnO ₂ , Bi ₂ O ₃ , MoO ₃ , Sb ₂ O. ₅ , WO ₃ , metal oxides such as phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, and silicomolybdic acid.

Among them, from the viewpoint of oxidation promoting _ability, it is preferably at least one selected from _{TiO 2, V 2 O 5,} SnO 2, Bi 2 O 3 and MoO _3.

When the oxidation accelerator is in a particulate form, the volume average particle diameter of the oxidation accelerator is preferably 20 μm or less, and more preferably 5 μm or less. When an oxidation accelerator having a volume average particle diameter of 20 μm or less is used, it is easy to mix uniformly with glass powder or a dispersion medium, and productivity is improved.
The lower limit of the volume average particle diameter is not particularly limited, but is preferably 0.01 μm or more. If it is 0.01 μm or more, the dispersibility in the paste becomes better.

It is preferable that 0.05-20 mass% is contained in an n type diffused layer formation composition, and, as for an oxidation accelerator, it is more preferable that 0.1-5 mass% is contained.
Moreover, it is preferable to add 1-200 mass% of an oxidation accelerator with respect to glass powder, and it is still more preferable to add 10-100 mass%. A sufficient oxidation promoting effect can be obtained when the content is 1% by mass or more. Moreover, an n type diffused layer can be more effectively formed as it is 200 mass% or less.

  From the viewpoint of n-type diffusion layer formation efficiency and suppression of striations, the n-type diffusion layer forming composition includes a glass powder containing 1 to 80% by mass of a donor element, and 0.1 to 30% by mass of a silicon-containing substance. The glass powder containing 2 to 80% by mass of the donor element and 1 to 30% by mass of the silicon-containing substance are more preferably configured to contain 5 to 20% by mass. It is more preferable that the glass powder contains a donor element, 2 to 20% by mass of a silicon-containing substance, and 0.1 to 5% by mass of an oxidation accelerator.

Next, the dispersion medium will be described.
The dispersion medium is a medium in which the glass powder is dispersed in the composition. Specifically, the dispersion medium includes at least a solvent and water, and includes an organic binder as necessary.

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 n-propyl ether, diethylene glycol methyl n-butyl ether, diethylene glycol di -N-propyl ether, diethylene glycol di-n-butyl ether, diethylene glycol methyl-n-hexyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol methyl-n-butyl ether, triethylene Glycol di-n-butyl ether, triethylene glycol methyl-n-hexyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetradiethylene glycol methyl ethyl ether, tetraethylene glycol methyl n-butyl ether, diethylene glycol di-n-butyl ether, Tetraethylene glycol methyl-n-hexyl ether, tetraethylene glycol di-n-butyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n-propyl ether, propylene glycol dibutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol Diethyl ether, dipropi N-glycol methyl ethyl ether, dipropylene glycol methyl-n-butyl ether, dipropylene glycol di-n-propyl ether, dipropylene glycol di-n-butyl ether, dipropylene glycol methyl-n-hexyl ether, tripropylene glycol dimethyl ether, tripropylene glycol 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 , Tetradipropylene glycol methyl ethyl ether, tetrapropylene Ether solvents such as N-glycol methyl-n-butyl ether, dipropylene glycol di-n-butyl ether, tetrapropylene glycol methyl n-hexyl ether, tetrapropylene glycol di-n-butyl ether, methyl acetate, ethyl acetate, n-acetate Propyl, i-propyl acetate, n-butyl acetate, i-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethyl acetate Ethylhexyl, 2- (2-butoxyethoxy) ethyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, nonyl acetate, methyl acetoacetate, ethyl acetoacetate, diethylene glycol monomethyl ether acetate, diethylene glycol acetate Monoethyl ether, diethylene glycol acetate mono-n-butyl ether, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, glycol diacetate, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, i-propionate i- Ester solvents such as amyl, 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, diethylene glycol ethyl ether acetate , Ether acetate solvents such as 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, acetonitrile, N- Aprotic polarities such as methylpyrrolidinone, N-ethylpyrrolidinone, N-propylpyrrolidinone, N-butylpyrrolidinone, N-hexylpyrrolidinone, N-cyclohexylpyrrolidinone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide Solvent, methanol, ethanol, n-propanol, i-propanol, n-butano , I-butanol, sec-butanol, t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, sec-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2 -Methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, phenol, cyclohexanol, methylcyclohexanol, benzyl alcohol, ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol Alcohol solvents such as 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 , Glycol monoethers such as 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 monomethyl ether Solvent, alpha-terpinene, alpha-terpineol, myrcene, alloocimene, limonene, dipentene, alpha-pinene, beta-pinene, terpineol, carvone, ocimene, terpene type solvents such as phellandrene like. These are used singly or in combination of two or more.
In the case of an n-type diffusion layer forming composition, α-terpineol, diethylene glycol mono-n-butyl ether, and diethylene glycol mono-n-butyl ether are preferred, and α-terpineol, diethylene glycol mono-n- from the viewpoint of applicability to the substrate. Butyl ether is mentioned as a preferred solvent.

  Examples of the organic binder include polyvinyl alcohol, polyacrylamides, polyvinyl amides, polyvinyl pyrrolidone, polyethylene oxides, polysulfonic acid, acrylamide alkyl sulfonic acid, cellulose ethers, cellulose derivatives, carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose, gelatin, Starch and starch derivatives, sodium alginate, xanthan, guar and gua derivatives, scleroglucan and scleroglucan derivatives, tragacanth and tragacanth derivatives, dextrin and dextrin derivatives, (meth) acrylic acid resin, (meth) acrylic acid ester resin ( For example, alkyl (meth) acrylate resin, dimethylaminoethyl (meth) acrylate resin, etc.), butadiene Fat, styrene resins, and may select such a copolymer thereof as appropriate. These are used singly or in combination of two or more.

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

  The constitution and content ratio of the dispersion medium in the n-type diffusion layer forming composition are determined in consideration of coating properties and donor concentration.

  In addition to the glass powder containing the donor element, the silicon-containing material and the dispersion medium, and the organic binder and oxidation accelerator contained as necessary, the n-type diffusion layer forming composition includes various additives, A thickener or wetting agent may be added. Examples of other components include surfactants, inorganic powders, organic boron compounds, organic aluminum compounds, and resins containing silicon atoms.

  Examples of the surfactant include nonionic surfactants, cationic surfactants, and anionic surfactants. Among these, nonionic surfactants or cationic surfactants are preferable because impurities such as alkali metals and heavy metals are not brought into the semiconductor device. Furthermore, examples of nonionic surfactants include silicon surfactants, fluorine surfactants, and hydrocarbon surfactants. However, since they are rapidly fired during overheating such as diffusion, hydrocarbon surfactants Agents are preferred.

  Examples of the hydrocarbon-based surfactant include block copolymers of ethylene oxide-propylene oxide, acetylene glycol compounds, and the like. However, acetylene glycol compounds are more preferable because variations in resistance values of semiconductor devices are further reduced. .

  The inorganic powder can function as a filler, and examples thereof include boron nitride, silicon oxide, titanium oxide, aluminum oxide, silicon nitride, and silicon carbide.

  As the organic boron compound, any organic boron polymer may be used as long as it contains 10 or more boron atoms in the molecule, and the molecular structure is not particularly limited.

  The n-type diffusion layer forming composition may include an additive for reducing the glass component. For example, polyalkylene glycols such as polyethylene glycol and polypropylene glycol and terminal alkylated products thereof; monosaccharides or derivatives thereof such as glucose, fructose and galactose; disaccharides or derivatives thereof such as sucrose and maltose; and polysaccharides or derivatives thereof Can be mentioned. Among these organic compounds, polyalkylene glycol is preferable, and polypropylene glycol is more preferable. Addition of an additive that reduces the glass component may facilitate the diffusion of the donor element into the silicon substrate.

  The n-type diffusion layer forming composition may include a thixotropic agent containing a solid content. Thereby, the thixotropy can be easily controlled, and a paste composition for screen printing having a viscosity suitable for printing can be constituted. Furthermore, since thixotropy is controlled, bleeding and sagging from the print pattern of the paste during printing can be suppressed.

  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 crystalline silicon as the p-type semiconductor substrate 10 to remove the 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.
Although there is no restriction | limiting in particular as an application quantity of the said n type diffused layer formation composition, For example, it can be set as 0.01-100 g / m < ² > as a glass powder quantity, and should be 0.1-10 g / m < ² >. Is preferred.

  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 to 300 ° C. for about 1 to 10 minutes when using a hot plate, and about 10 to 30 minutes when using a dryer or the like. 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).

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 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 can be 1 to 60 minutes, and more preferably 2 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. Only the n-type diffusion layer 12 is formed, and unnecessary n-type diffusion layers are not formed on the back surface and side surfaces.
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, due to the improvement of slicing technology, the thickness of the crystalline silicon substrate is being reduced, 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.
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), Cu (copper), or the like 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 to 2 Torr, the temperature during film formation is 300 to 550 ° C., and plasma discharge Is formed under the condition of a frequency of 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 for several seconds to several minutes in the range of 600 to 900 ° C., 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 surface of the silicon 10 is also partially melted. 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 only at a specific site, and therefore can be suitably applied to the production of a back-contact solar cell.

  Specifically, for example, a back contact solar cell can be manufactured by a manufacturing method including a manufacturing process as schematically shown in FIG.

The p-type p-type diffusion layer forming composition to the surface of the semiconductor substrate 1 and the n-type diffusion layer forming composition, partially coated respectively, by heat-treating this, p ⁺ -type diffusion layer 3 and the n-type diffusion layer 6 can each be formed in a specific region. The paste can be applied by ink jet or pattern printing.
As a result, as shown in FIG. 3A, the heat-treated material layer 2 of the p-type diffusion layer forming composition is formed on the p ⁺ -type diffusion layer 3 of the p-type semiconductor substrate 1. A heat-treated product layer 5 of the n-type diffusion layer forming composition is formed thereon.

Next, the heat-treated product layer 2 of the p-type diffusion layer forming composition formed on the p ⁺ -type diffusion layer 3 and the heat-treated product of the n-type diffusion layer forming composition formed on the n-type diffusion layer 6 Layer 5 is removed by etching or the like.
As a result, as shown in FIG. 3B, the heat-treated product layer 2 of the p-type diffusion layer forming composition and the heat-treated product layer 5 of the n-type diffusion layer forming composition in FIG. Thus, the p-type semiconductor substrate 1 in which the p ⁺ -type diffusion layer 3 and the n-type diffusion layer 6 are selectively formed is obtained.

Next, a reflective film or surface protective film 7 is formed on the p-type semiconductor substrate 1 by a conventional method. At this time, as shown in FIG. 3C1, a reflective film or a surface protective film 7 may be partially formed so that the p ⁺ -type diffusion layer 3 and the n-type diffusion layer 6 are exposed on the surface.
Further, as shown in FIG. 3C2, a reflective film or a surface protective film 7 may be formed on the entire surface of the p-type semiconductor substrate 1.

Next, an electrode paste is selectively applied and heat-treated on the p ⁺ -type diffusion layer 3 and the n-type diffusion layer 6, so that the p ⁺ -type diffusion layer 3 and the n-type diffusion layer are formed as shown in FIG. An electrode 4 and an electrode 8 can be formed on 6.
When a reflective film or a surface protective film is formed on the entire surface of the p-type semiconductor substrate 1 as shown in FIG. 3 (c2), it is possible to use an electrode paste containing a glass powder having fire-through properties. As shown in FIG. 3D, the electrode 4 and the electrode 8 can be formed on the p ⁺ -type diffusion layer 3 and the n-type diffusion layer 6, respectively.

  In the solar cell manufactured by the manufacturing method including the manufacturing process shown in FIG. 3, since no electrode exists on the light receiving surface, sunlight can be taken in effectively.

  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>
[Synthesis Example 1]
(Synthesis of glass powder)
SiO ₂ (manufactured by Wako Pure Chemical Industries, Ltd.), P ₂ O ₅ (manufactured by Wako Pure Chemical Industries, Ltd.), CaCO ₃ (manufactured by Wako Pure Chemical Industries, Ltd.) are used as raw materials, and the respective molar ratios are SiO ₂ : P ₂ O ₅ : CaO. = 30:60:10, mixed in an alumina crucible, heated to 1400 ° C at 400 ° C / h, held for 1 hour, and then rapidly cooled. This was pulverized using an automatic mortar kneader to obtain a glass powder containing a donor element.
When the powder X-ray diffraction (XRD) pattern of the obtained glass powder was measured with an X-ray diffractometer (RINT-2000, manufactured by Rigaku Corporation) using Cu-Kα rays using a Ni filter, the obtained glass powder was obtained. Was confirmed to be amorphous.
Moreover, it was 8 micrometers when the volume average particle diameter of glass powder was measured with the laser diffraction type particle size distribution measuring apparatus.

(Preparation of n-type diffusion layer forming composition)
A terpineol (Nippon Terpene Chemical) solution containing 3.8% by mass of ethyl cellulose (Etocel manufactured by Nisshinsei) was prepared. 8 g of this solution, 1 g of the glass powder containing the donor element synthesized in Synthesis Example 1, and 1 g of amorphous SiO ₂ (made by high-purity chemical, particle diameter of about 1 μm) as a silicon-containing material are mixed in a mortar to form an n-type diffusion. A layer forming composition (hereinafter also simply referred to as “paste”) was prepared.

(Thermal diffusion and etching process)
The obtained paste was applied by screen printing on the surface of a sliced p-type silicon substrate (hereinafter also referred to as “p-type slice silicon substrate”), and dried on a hot plate at 150 ° C. for 5 minutes. Subsequently, air was supplied at 5 L / min. Thermal diffusion treatment was carried out for 10 minutes in a tunnel furnace at 950 ° C. that was flowed in Thereafter, in order to remove the glass layer formed on the surface of the p-type silicon substrate, the substrate is immersed in a 2.5% by mass HF aqueous solution for 6 minutes, and then washed with running water, ultrasonically washed, and dried to obtain n-type. A p-type silicon substrate on which a diffusion layer was formed was obtained.
Further, a p-type mirror wafer having a p-type diffusion layer formed was obtained in the same manner except that a p-type mirror wafer was used instead of the p-type slice silicon substrate.

[Evaluation]
(Sheet resistance measurement)
The sheet resistance of the surface of the p-type slice silicon substrate on which the n-type diffusion layer was formed was measured by a four-probe method using a Loresta-EP MCP-T360 type low resistivity meter manufactured by Mitsubishi Chemical Corporation.
The portion where the n-type diffusion layer forming composition was applied was 26Ω / □, and P (phosphorus) was diffused to form an n-type diffusion layer. The sheet resistance of the non-coated part was 1030Ω / □.

(Observation of substrate surface)
For the p-type mirror wafer on which the n-type diffusion layer was formed, the surface of the portion where the n-type diffusion layer forming composition was applied was observed using an optical microscope (Olympus) and a scanning electron microscope (Hitachi High-Tech). However, it was found that the occurrence of surface roughness was suppressed.

(Measurement of XRD pattern of substrate)
When the XRD pattern of the p-type slice silicon substrate on which the n-type diffusion layer was formed was measured, no peaks other than those derived from the silicon substrate were observed.

<Example 2>
In Example 1, a p-type slice silicon substrate and a p-type mirror wafer on which an n-type diffusion layer was formed in the same manner except that the addition amount of SiO ₂ as a silicon-containing material was changed from 1 g to 0.2 g. Obtained.
The sheet resistance of the portion where the n-type diffusion layer forming composition was applied was 27Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer. The sheet resistance of the non-coated part was 1005Ω / □. When the XRD pattern of the silicon substrate on which the n-type diffusion layer was formed was measured, no peaks other than those derived from the silicon substrate were observed.
Further, the occurrence of surface roughness of the p-type mirror wafer was suppressed.

<Example 3>
A p-type slice silicon substrate and a p-type mirror wafer on which an n-type diffusion layer was formed were obtained in the same manner as in Example 1 except that the amount of the glass powder containing the donor element was changed from 1 g to 3 g.
The portion where the p-type diffusion layer forming composition was applied was 26Ω / □, and P (phosphorus) was diffused to form an n-type diffusion layer. The sheet resistance of the non-coated part was 1010Ω / □. When the XRD pattern of the silicon substrate on which the n-type diffusion layer was formed was measured, no peaks other than those derived from the silicon substrate were observed.
Moreover, the occurrence of surface roughness of the n-type mirror wafer was suppressed.

<Comparative Example 1>
The same operation as in Example 1 was performed except that the amorphous SiO ₂ powder, which is a silicon-containing substance, was not added.
The portion where the n-type diffusion layer forming composition was applied was 26Ω / □, and P (phosphorus) was diffused to form an n-type diffusion layer. The sheet resistance of the non-coated part was 980Ω / □.
Further, when the XRD pattern of the p-type slice silicon substrate on which the n-type diffusion layer was formed was measured, a crystallization peak other than that derived from the silicon substrate was observed, and the reaction product of the glass component and the silicon substrate was observed even after the etching process. It was done.
Moreover, when the surface of the part which apply | coated the n type diffused layer formation composition about the p-type mirror wafer was observed, surface roughness was many and the stripe pattern by a height difference was observed.

From the above, it was found that by adding a silicon-containing substance such as SiO ₂ to the n-type diffusion layer forming composition, the surface roughness of the silicon substrate can be prevented, and the reaction between the glass component and the silicon substrate can be prevented. Furthermore, since the production | generation of the reaction material of glass and a board | substrate is suppressed, the raise of the ohmic contact resistance at the time of forming an electrode can be suppressed.

1 p-type semiconductor substrate 2, 5 heat-treated material layer 3 p ⁺ -type diffusion layer 4, 8 electrode 6 n-type diffusion layer 7 reflective film or surface protective film 10 p-type semiconductor substrate 12 n-type diffusion layer 14 high concentration electric field layer 16 reflection Prevention film 18 Front electrode 20 Back electrode (electrode layer)
30 Busbar electrode 32 Finger electrode

Claims (9)

  An n-type diffusion layer forming composition containing a glass powder containing a donor element, a silicon-containing substance, and a dispersion medium.   The n-type diffusion layer forming composition according to claim 1, wherein the donor element is at least one selected from P (phosphorus) and Sb (antimony).   The n-type diffusion layer forming composition according to claim 1 or 2, wherein the silicon-containing substance is a silicon oxide. 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 n-type diffused layer formation composition of any one of Claim 3.   The n-type diffusion layer forming composition according to any one of claims 1 to 4, further comprising an organic binder.   The n according to any one of claims 1 to 5, comprising 1% by mass or more and 80% by mass or less of the glass powder and 0.1% by mass or more and 30% by mass or less of the silicon-containing substance. Mold diffusion layer forming composition.   The n-type diffusion layer forming composition according to claim 1, wherein the glass powder has a volume average particle size of 0.1 μm or more and 10 μm or less. Applying an n-type diffusion layer forming composition according to any one of claims 1 to 7 on a semiconductor substrate;
A step of applying a thermal diffusion treatment;
The manufacturing method of the n type diffused layer which has this. Applying an n-type diffusion layer forming composition according to any one of claims 1 to 7 on a semiconductor substrate;
Performing a thermal diffusion treatment to form an n-type diffusion layer;
Forming an electrode on the formed n-type diffusion layer;
The manufacturing method of the photovoltaic cell which has this.