CN107093550A - The manufacture method of n-type diffusion layer formation composition, the manufacture method of n-type diffusion layer and solar cell device - Google Patents

Abstract

The present invention provides a composition for forming an n-type diffusion layer, comprising: a glass powder containing a donor element, having a softening temperature of 500° C. to 900° C., and an average particle diameter of 5 μm or less; and a dispersion medium.

Description

Composition for forming n-type diffused layer, method for producing n-type diffused layer, and solar energy Manufacturing method of battery element

This invention is a divisional application of the invention patent with application number 201280031501.5. The filing date of the parent application is July 3, 2012, and the invention name of the parent application is the same as the above-mentioned name.

technical field

The present invention relates to a composition for forming an n-type diffused layer of a solar cell element, a method for manufacturing an n-type diffused layer, and a method for manufacturing a solar cell element. A technique for forming an n-type diffusion layer in a specific area.

Background technique

The manufacturing process of the conventional silicon solar cell element is demonstrated.

First, a p-type silicon substrate with a textured structure formed on the light-receiving surface is prepared in order to promote the light trapping effect and achieve high efficiency. Next, phosphorous oxychloride (POCl ₃ ), nitrogen, and oxygen In a mixed gas atmosphere, the n-type diffusion layer is similarly formed by performing treatment at 800° C. to 900° C. for several tens of minutes. In this conventional method, since phosphorus is diffused using a mixed gas, an n-type diffusion layer is formed not only on the surface but also on the side surface and the rear surface. Therefore, a side etching process for removing the n-type diffusion layer on the side surface is required. In addition, the n-type diffused layer on the back must be converted to a p ⁺ -type diffused layer, and an aluminum paste is applied to the n-type diffused layer on the back, and the n-type diffused layer is converted to a p ⁺ -type diffused layer by the diffusion of aluminum.

On the other hand, in the field of semiconductor manufacturing, a method has been proposed in which a compound containing phosphorus pentoxide (P ₂ O ₅ ) or ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ) is coated as a compound containing a donor element. A phosphate solution is used to form an n-type diffusion layer (for example, refer to Japanese Patent Application Laid-Open No. 2002-75894). In addition, in order to form a diffusion layer, a paste containing phosphorus as a donor element is coated on the surface of a silicon substrate as a diffusion source and thermally diffused to form a diffusion layer. ).

Contents of the invention

The problem to be solved by the invention

However, in these methods, the donor element or a compound containing it scatters from the solution or paste used as a diffusion source, so phosphorus also diffuses to the sides and On the back side, an n-type diffused layer is also formed outside the coated portion. In addition, generally, the upper surface of a semiconductor substrate such as a silicon substrate used in a solar cell has a textured structure in which a difference in height between a convex portion and a concave portion is about 5 μm. Since the coating is applied on a surface with such a textured structure, the n-type diffusion layer may not be uniformly formed.

In this way, when forming an n-type diffusion layer, in the gas phase reaction using phosphorus oxychloride, not only an n-type diffusion layer is formed on the side (usually the light-receiving side or surface) that originally needs an n-type diffusion layer, but also on the other side ( The n-type diffusion layer is also formed on the non-light-receiving surface or the back) or the side. In addition, in the method of applying a solution or paste containing a phosphorus-containing compound and performing thermal diffusion, an n-type diffusion layer is also formed on the surface as in the gas phase reaction method. Therefore, in order to make the element have a pn junction structure, it is necessary to etch on the side and convert the n-type diffusion layer into a p-type diffusion layer on the back. Usually, a paste of aluminum, which is a Group 13 element, is applied on the back surface and fired to convert the n-type diffusion layer into a p-type diffusion layer. In addition, when the solution is applied, phosphorus diffuses non-uniformly to form a non-uniform n-type diffusion layer, resulting in a decrease in the conversion efficiency of the solar cell as a whole. Furthermore, in the previously known method of applying a paste containing a donor element such as phosphorus as a diffusion source, the compound containing the donor element volatilizes and vaporizes, and also diffuses outside the area where diffusion is required, so it is difficult to selectively to form a diffusion layer in a specific area.

The present invention has been made in view of the above conventional problems, and its object is to provide a composition for forming an n-type diffused layer, a method for manufacturing an n-type diffused layer, and a method for manufacturing a solar cell element, wherein the n-type diffused layer The forming composition can be applied to a solar cell element using a semiconductor substrate, and can form a uniform n-type diffused layer in a specific region in a short time without forming an n-type diffused layer in an unnecessary region.

means to solve the problem

Means for solving the above-mentioned problems are as follows.

<1> A composition for forming an n-type diffusion layer, comprising: a glass powder containing a donor element, having a softening temperature of 500° C. to 900° C., and an average particle diameter of 5 μm or less; and a dispersion medium.

<2> The composition for forming an n-type diffused layer according to the above <1>, wherein d90 of the glass powder is 20 μm or less.

<3> The composition for forming an n-type diffusion layer according to <1> or <2>, wherein the donor element is at least one selected from P (phosphorus) and Sb (antimony).

<4> The composition for forming an n _- type diffused layer according to any one of < ₁ > to < ₃ >, wherein the glass powder containing the above _- mentioned donor element contains: At least one donor element-containing substance from the group consisting of Sb ₂ O ₃ , and a substance selected from the group consisting of SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, and PbO , CdO, SnO, ZrO ₂ and MoO ₃ at least one glass component substance in the group consisting of.

<5> A method for producing an n-type diffused layer, comprising: applying the composition for forming an n-type diffused layer according to any one of <1> to <4> on a semiconductor substrate; The subsequent semiconductor substrate is subjected to a process of thermal diffusion treatment.

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

<7> Use of the composition for forming an n-type diffused layer according to any one of <1> to <4> for producing an n-type diffused layer.

<8> Use of the composition for forming an n-type diffused layer according to any one of <1> to <4> to manufacture a solar cell element including a semiconductor substrate, an n-type diffused layer, and an electrode.

The effect of the invention

According to the present invention, there can be provided a composition for forming an n-type diffused layer, a method for producing an n-type diffused layer, and a method for producing a solar cell element, wherein the composition for forming an n-type diffused layer can be applied to a solar cell using a semiconductor substrate. An element that does not form an n-type diffusion layer in an unnecessary region, and can form a uniform n-type diffusion layer in a specific region in a short time.

Description of drawings

FIG. 1 is a cross-sectional view conceptually showing an example of the manufacturing process of the solar cell element of the present invention.

Fig. 2A is a plan view of the solar cell element viewed from the surface.

FIG. 2B is an enlarged perspective view showing part of FIG. 2A .

detailed description

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

In addition, in this specification, the term "process" does not only refer to an independent process, but when it cannot be clearly distinguished from other processes, as long as the intended function of the process is achieved, it is also included in this term. In addition, in this specification, "-" shows the range which includes the numerical value described before and after that as a minimum value and a maximum value, respectively. Furthermore, in this specification, in terms of the amount of each component in the composition, when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, it means that the amount of each component present in the composition The total amount of multiple substances.

The composition for forming an n-type diffused layer of the present invention includes a glass powder (hereinafter, sometimes simply referred to as "glass powder") containing at least a donor element, having a softening temperature of 500° C. to 900° C., and an average particle diameter of 5 μm or less. and a dispersion medium; furthermore, other additives may be contained as necessary in consideration of imparting adaptability (coatability) of the composition, and the like.

Here, the composition for forming an n-type diffusion layer refers to a material that includes a donor element, has a softening temperature of 500° C. to 900° C., and an average particle diameter of 5 μm or less glass powder, which is applied to a semiconductor substrate. Then, the donor element is thermally diffused to form an n-type diffusion layer.

Viscosity of the glass during thermal diffusion treatment is not changed by using a composition for forming an n-type diffused layer containing a donor element, having a softening temperature of 500° C. to 900° C., and glass powder having an average particle diameter of 5 μm or less. In addition, the glass powder is melted in a short time. Thereby, an n-type diffused layer is formed in a desired position, and an unnecessary n-type diffused layer is not formed on the back surface or the side surface.

Therefore, when the composition for forming an n-type diffused layer of the present invention is applied, the side etching process required in the conventional gas phase reaction method widely used is unnecessary, and the process can be simplified. Also, there is no need for a step of converting the n-type diffusion layer formed on the rear surface into a p ⁺ -type diffusion layer. Therefore, the method of forming the p ⁺ -type diffusion layer on the back surface, or the material, shape, and thickness of the back electrode are not limited, and the freedom of selection of the manufacturing method, material, and shape to be applied is expanded. In addition, generation of internal stress in the semiconductor substrate due to the thickness of the back electrode is suppressed, and warping of the semiconductor substrate is also suppressed, details of which will be described later.

In addition, the glass powder contained in the n-type diffused layer-forming composition of the present invention is melted by firing to form a glass layer on the n-type diffused layer. However, in the conventional gas phase reaction method or the method of applying a phosphate-containing solution or paste, a glass layer is also formed on the n-type diffusion layer, so the glass layer produced in the present invention can be formed in the same manner as the conventional method. removed by etching. Therefore, the composition for forming an n-type diffusion layer of the present invention does not generate unnecessary products and does not increase the number of steps even when compared with the conventional methods.

In addition, the donor component in the glass powder is also less likely to volatilize during firing, so that the n-type diffused layer is suppressed from being formed not only on the surface but also on the back or side surfaces due to the generation of volatilized gas.

The reason for this is considered to be that the donor component is strongly bonded to other constituent elements in the glass, so that it does not volatilize easily.

In this way, the composition for forming an n-type diffused layer of the present invention can form an n-type diffused layer at a desired concentration at a desired location, and thus can form a selective region with a high concentration of n-type donor elements (dopants). . On the other hand, it is generally difficult to form a selective region with a high concentration of n-type donor elements by a gas phase reaction method, which is a general method for n-type diffusion layers, or by using a solution containing phosphate alone.

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

The term "donor element" refers to an element capable of forming an n-type diffusion layer by diffusing (doping) in the semiconductor substrate. As the donor element, an element of Group 15 can be used, and examples thereof include P (phosphorus), Sb (antimony), Bi (bismuth), and As (arsenic). From the viewpoint of safety, easiness of vitrification, etc., P or Sb is suitable.

Examples of the donor element-containing substance 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 . At least one selected from the group consisting of P ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ .

In addition, the glass powder containing the donor element can adjust the component ratio as needed, thereby controlling the melting temperature, softening temperature, glass transition temperature, chemical durability, and the like. It is preferable to further contain glass component substances described below.

Examples of glass components include SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, 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 , etc., preferably used selected from SiO ₂ , K ₂ O , Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO ₂ , WO ₃ , MoO ₃ , and MnO, more preferably At least one selected from the group consisting of SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO ₂ and MoO ₃ .

Specific examples of the glass powder containing the donor element include a system including both the above-mentioned donor element-containing substance and the above-mentioned glass component substance, such as: P ₂ O ₅ -SiO ₂ system (based on the donor element-containing Substance-Glass components are described in the order of substances, the same below), P ₂ O ₅ -K ₂ O system, P ₂ O ₅ -Na ₂ O system, P ₂ O ₅ -Li ₂ O system, P ₂ O ₅ -BaO system , P ₂ O ₅ -SrO system, P ₂ O ₅ -CaO system, P ₂ O ₅ -MgO system, P ₂ O ₅ -BeO system, P ₂ O ₅ -ZnO system, P ₂ O ₅ -CdO system, P ₂ O ₅ -PbO system, P ₂ O ₅ -SnO system, P ₂ O ₅ -GeO ₂ system, P ₂ O ₅ -TeO ₂ system, etc. containing P ₂ O ₅ as a donor element-containing system, instead of the above-mentioned _{A glass powder of a P 2 O 5 system containing Sb 2 O 3 as a donor element -} containing substance.

In addition, glass powders containing two or more kinds of donor element-containing substances such as P ₂ O ₅ -Sb ₂ O ₃ systems and P ₂ O ₅ -As ₂ O ₃ systems may be used.

In the above, the composite glass containing two components was exemplified, but glass powder containing three or more components as needed, such as P ₂ O ₅ -SiO ₂ -CaO, may also be used.

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

Specifically, when SiO ₂ is contained in the glass powder, the content ratio of SiO ₂ is preferably in the range of not less than 10% by mass and not more than 90% by mass.

The softening temperature of the glass powder must be 500° C. or higher and 900° C. or lower from the viewpoint of diffusibility and dripping during the diffusion treatment. Moreover, it is preferably 600°C or more and 800°C or less, and more preferably 700°C or more and 800°C or less. When the softening temperature is lower than 500° C., the viscosity of the glass becomes too low during the diffusion treatment and dripping occurs, so that an n-type diffusion layer may be formed also in other than specific portions. In addition, when the softening temperature is higher than 900° C., the glass powder may not be completely melted, so that a uniform n-type diffusion layer may not be formed.

If the softening temperature of the glass powder is in the range of 500°C to 900°C, dripping will not occur as described above, so after the diffusion treatment, the n-type diffusion layer can be formed in a desired area. shape. For example, when the composition for forming an n-type diffusion layer is provided as a linear pattern having a width of a μm, the linear pattern whose line width b after the diffusion treatment is in the range of b<1.5 a μm can be maintained.

The softening temperature of the glass powder can be determined from a differential thermal (DTA) curve or the like using a DTG-60H differential thermal/thermogravimetric simultaneous measuring device manufactured by Shimadzu Corporation.

As the shape of the glass powder, there are roughly spherical, flat, massive, plate-like, and scaly shapes, etc., from the coatability (imparting adaptability) to the substrate when it is made into an n-type diffusion layer-forming composition or From the viewpoint of uniform diffusibility, it is preferably approximately spherical, flat or plate-shaped.

The average particle diameter of the glass powder needs to be 5 μm or less. Moreover, it is preferably 0.1 μm to 5 μm, more preferably 0.5 μm to 4 μm.

By setting the average particle diameter of the glass powder to 5 μm or less, even when using a glass powder having a softening temperature within the above range, it melts in a short time, and a smooth glass layer is easily obtained. Therefore, by setting the average particle size of the glass powder to 5 μm or less, a uniform n-type diffused layer can be formed.

Whether or not the n-type diffusion layer is uniform can be confirmed, for example, by the variation (standard deviation: σ) of the sheet resistance in the n-type diffusion layer obtained by coating on the semiconductor substrate. When the variation (σ) of the sheet resistance value is, for example, 10 or less, preferably 5 or less, more preferably 2 or less, it can be evaluated that a uniform n-type diffused layer is formed.

In the present invention, a value measured at 25° C. by a four-probe method using a Loresta-EP MCP-T360 low resistivity meter manufactured by Mitsubishi Chemical Corporation was used as the sheet resistance.

In addition, σ is calculated from the square root of the value obtained by dividing the sum of the squares of the deviations of the sheet resistance values at 25 points in the coated surface obtained by the above measurement method by the number of data.

In addition, generally, the upper surface of a semiconductor substrate used in a solar cell has a textured structure in which a difference in height between a convex portion and a concave portion is about 5 μm. Therefore, by setting the average particle size of the glass powder to 5 μm or less, since the followability to the surface of the concave portion is improved, diffusion unevenness can also be reduced.

Here, in this specification, unless otherwise specified, the average particle diameter of the glass means a volume average particle diameter, and can be measured with a laser scattering diffraction particle size distribution analyzer (manufactured by Beckman Coulter) or the like.

The d90 of the glass powder used in the present invention is preferably 20 μm or less. In addition, d90 is more preferably 15 μm or less, still more preferably 10 μm or less. Here, d90 refers to the particle diameter at which 90% of the whole is accumulated sequentially from the particle with the smallest particle diameter when the cumulative volume distribution curve of the particle diameter is drawn. The volume distribution cumulative curve can be measured in the same manner as the average particle size described above, and can be measured with a laser light scattering diffraction particle size distribution analyzer (manufactured by Beckman Coulter) or the like.

If the d90 of the above-mentioned glass powder is 20 μm or less, there is a tendency that after the above-mentioned composition for forming an n-type diffusion layer is applied to the upper surface of the semiconductor substrate, the generation of large pores caused by coarse particles can be suppressed, and The distribution of the donor elements can be made more uniform.

The glass powder in the present invention needs to have a softening temperature of 500° C. to 900° C. and an average particle diameter of 5 μm or less. In addition, the softening temperature of the glass is preferably 600°C to 800°C, and the average particle size is 0.1 µm to 5 µm, more preferably the softening temperature of the glass is 700°C to 800°C, and the average particle size is 0.5 µm to 4 µm.

In addition, for the above-mentioned glass powder, it is preferable that the softening temperature of the glass powder is 500° C. to 900° C., the average particle diameter is 5 μm or less, and the d90 is 20 μm or less. More preferably, the softening temperature of the glass is 600° C. to 600° C. 800°C, the average particle size is 0.1 μm to 5 μm, and the d90 is 15 μm or less. More preferably, the softening temperature of the glass is 700° C. to 800° C., the average particle size is 0.5 μm to 4 μm, and the d90 is 10 μm or less.

In addition, for the above-mentioned glass powder, it is more preferable that the softening temperature of the glass is 600° C. to 800° C., the average particle size is 0.1 μm to 5 μm, and the d90 is 15 μm or less, and the glass powder containing the above-mentioned donor element includes: At least one donor element-containing substance from the group consisting of P ₂ O ₃ , P ₂ O ₅ , and Sb ₂ O ₃ , and a substance selected from the group consisting of SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, and SrO , CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO ₂ and MoO ₃ at least one glass component material in the group consisting of, more preferably, the softening temperature of the glass is 700 ° C ~ 800 ° C, the average Glass powder with a particle size of 0.5 μm to 4 μm, d90 of 10 μm or less, and containing the above-mentioned donor element includes at least one donor element selected from the group consisting of P ₂ O ₃ , P ₂ O ₅ and Sb ₂ O ₃ and substances selected from the group consisting of SiO ₂ , K ₂ O, Na ₂ O, Li ₂ O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO ₂ and MoO ₃ At least one glass constituent substance.

A glass powder containing a donor element is produced by the following procedure.

First, raw materials, for example, the above-mentioned donor element-containing substance and glass component substance are weighed, and then filled into a crucible. Examples of the material of the crucible include platinum, platinum-rhodium, iridium, alumina, quartz, carbon, and the like. The material of the crucible can be appropriately selected in consideration of melting temperature, environment, reactivity with molten substances, and the like.

Next, the material containing the donor element and the glass component material are heated at a temperature suitable for the composition of the glass in an electric furnace to form a melt. At this time, it is desirable to stir so that the melt becomes uniform.

Next, the obtained melt is flowed onto a zirconia substrate, a carbon substrate, or the like to vitrify the melt.

Finally, the glass is pulverized to form a powder. For pulverization, known methods such as a jet mill, a bead mill, and a ball mill can be applied.

The content ratio of the donor element-containing glass powder in the composition for forming an n-type diffused layer is determined in consideration of the diffusivity of the donor element to impart adaptability (coatability), and the like. Generally, the content ratio of the glass powder in the composition for forming an n-type diffusion layer is preferably 0.1% by mass to 95% by mass, more preferably 1% by mass to 90% by mass, still more preferably 1.5% by mass It is not less than 85% by mass, particularly preferably not less than 2% by mass and not more than 80% by mass.

Hereinafter, the dispersion medium will be described.

The term "dispersion medium" refers to a medium for dispersing the above-mentioned glass powder in the composition. Specifically, at least one selected from the group consisting of binders and solvents is used as the dispersion medium.

Examples of binders include polyvinyl alcohol, polyacrylamide resin, polyvinylamide resin, polyvinylpyrrolidone, polyethylene oxide resin, polysulfonic acid, acrylamide alkylsulfonic acid, and cellulose ether resin. , cellulose derivatives, carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose, gelatin, starch and starch derivatives, sodium alginate and sodium alginate derivatives, xanthan gum and xanthan gum derivatives , guar gum and guar gum derivatives, scleroglucan and scleroglucan derivatives, tragacanth and tragacanth gum derivatives, dextrin and dextrin derivatives, (meth)acrylic resins, (formazan base) acrylate resins (such as alkyl (meth)acrylate resins, dimethylaminoethyl (meth)acrylate resins, etc.), butadiene resins, styrene resins, and copolymers thereof. In addition, a silicone resin can also be selected appropriately. These binders may be used alone or in combination of two or more.

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

Examples of solvents include: acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-isopropyl ketone, methyl-n-butyl ketone, methyl-isobutyl ketone, methyl -n-amyl ketone, methyl-n-hexyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, trimethylnonanone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2 , 4-pentanedione, acetonyl acetone and other ketone solvents; diethyl ether, methyl ethyl ether, methyl-n-propyl ether, diisopropyl ether, tetrahydrofuran, methyl tetrahydrofuran, dioxane, dimethyldiox Alkanes, 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 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 Alcohol methyl n-hexyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene 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, Propylene glycol methyl ethyl ether, dipropylene glycol methyl n-butyl ether, dipropylene glycol di-n-propyl ether, dipropylene glycol di-n-butyl ether, dipropylene glycol methyl n-hexyl ether, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, tripropylene glycol methyl Diethyl ether, tripropylene glycol methyl n-butyl ether, tripropylene glycol di-n-butyl ether, tripropylene glycol methyl n-hexyl ether, tetrapropylene glycol dimethyl ether, tetrapropylene glycol diethyl ether, tetrapropylene glycol methyl ethyl ether, tetrapropylene glycol methyl Ether solvents such as 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-propyl acetate, isopropyl acetate, n-butyl acetate , isobutyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate ester, 2-(2-butoxyethoxy)ethyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, nonyl acetate, methyl acetoacetate, ethyl acetoacetate, diethyl Glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, ethylene glycol diacetate, methoxytriethylene glycol Alcohol acetate, ethyl propionate, n-butyl propionate, isopentyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-pentyl lactate , ethylene glycol monomethyl ether propionate, ethylene glycol monoethyl ether propionate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether Acetate, propylene glycol monopropyl ether acetate, γ-butyrolactone, γ-valerolactone and other ester solvents; acetonitrile, N-methylpyrrolidone, N-ethylpyrrolidone, N-propylpyrrolidone, N-butyl Basepyrrolidone, N-hexylpyrrolidone, N-ring Hexylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide and other aprotic polar solvents; methanol, ethanol, n-propanol, isopropanol, n-butyl alcohol, isobutanol, sec-butanol, tert-butanol, n-pentanol, isoamyl alcohol, 2-methylbutanol, sec-pentanol, tert-amyl alcohol, 3-methoxybutanol, n-hexanol, 2- Methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n-nonanol, n-decyl alcohol, sec-undecyl alcohol, trimethyl Nonanol, sec-tetradecanol, sec-heptadecyl alcohol, phenol, cyclohexanol, methylcyclohexanol, benzyl alcohol, ethylene glycol, 1,2-propanediol, 1,3-butanediol, diethylene glycol Alcohol solvents such as alcohol, dipropylene glycol, triethylene glycol, and tripropylene glycol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether , Diethylene glycol mono-n-butyl ether, diethylene glycol mono-n-hexyl ether, triethylene glycol monoethyl ether, tetraethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, Glycol monoether solvents such as tripropylene glycol monomethyl ether; α-terpinene, α-terpineol, myrcene, alloocimene, limonene, dipentene, α-pinene, β-pinene, pine oil Alcohol, carvone, ocimene, phellandrene and other terpene solvents; water. These solvents may be used alone or in combination of two or more. When preparing an n-type diffusion layer-forming composition, from the viewpoint of imparting adaptability to the substrate, α-terpineol, diethylene glycol mono-n-butyl ether, and diethylene glycol mono-n-butyl ether acetate are preferable. , As more preferable solvents, α-terpineol and diethylene glycol mono-n-butyl ether are mentioned.

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

In consideration of imparting adaptability, the viscosity of the composition for forming an n-type diffusion layer is more preferably 10 mPa·s or more and 1,000,000 mPa·s or less.

The method for producing an n-type diffused layer of the present invention includes the steps of applying the composition for forming an n-type diffused layer on a semiconductor substrate, and performing a thermal diffusion treatment on the semiconductor substrate after the application. In addition, the method for producing a solar cell element of the present invention includes the steps of applying the composition for forming an n-type diffusion layer on a semiconductor substrate; and performing a thermal diffusion treatment on the semiconductor substrate after the application to form an n-type diffusion layer. and a step of forming an electrode on the formed n-type diffusion layer.

The n-type diffused layer and the method of manufacturing the solar cell element of the present invention will be described with reference to FIG. 1 . FIG. 1 is a schematic cross-sectional view conceptually showing an example of the manufacturing process of the solar cell element of the present invention. In addition, in FIG. 1, 10 denotes a p-type semiconductor substrate, 12 denotes an n-type diffusion layer, 14 denotes a p ⁺ type diffusion layer, 16 denotes an antireflection film, 18 denotes a surface electrode, and 20 denotes a back electrode (electrode layer). In the following drawings, the same reference numerals are assigned to the same constituent elements, and description thereof will be omitted. In addition, an example in which a silicon substrate is used as a p-type semiconductor substrate will be described below, but in the present invention, the semiconductor substrate is not limited to a silicon substrate.

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

Specifically, the damaged layer on the silicon surface generated when slicing from the ingot was removed with 20% by mass of caustic soda. Next, etching was performed with a mixed solution of 1% by mass of caustic soda and 10% by mass of isopropyl alcohol to form a textured structure (description of the textured structure is omitted in the figure). In solar cell elements, by forming a textured structure on the light-receiving surface (surface) side, the light trapping effect is promoted and efficiency can be increased.

In FIG. 1(2), the n-type diffusion layer-forming composition is applied to the surface of the p-type semiconductor substrate 10 , that is, the light-receiving surface, to form an n-type diffusion layer-forming composition layer 11 . In the present invention, the application method is not limited, and examples thereof include a printing method, a spin coating method, a brush coating method, a spray method, a doctor blade method, a roll coater method, and an inkjet method.

The amount of the composition for forming an n-type diffused layer to be provided is not particularly limited. For example, the amount of glass powder may be 0.01 g/m ² to 100 g/m ² , preferably 0.1 g/m ² to 10 g/m ² .

In addition, depending on the composition of the composition for forming an n-type diffusion layer, a drying step for volatilizing the solvent contained in the composition may be required after application. At this time, when using a hot plate at a temperature of about 80° C. to 300° C., it is dried for 1 minute to 10 minutes, and when a drier or the like is used, it is dried for about 10 minutes to 30 minutes. The drying conditions depend on the solvent composition of the composition for forming an n-type diffusion layer, and are not particularly limited to the above conditions in the present invention.

In addition, when using the manufacturing method of the present invention, the manufacturing method of the p ⁺ -type diffused layer (high-concentration electric field layer) 14 on the back is not limited to the method of converting an n-type diffused layer into a p-type diffused layer based on aluminum. With any of the previously known methods, the freedom of choice of the manufacturing method is expanded. Therefore, for example, the composition 13 containing a group 13 element such as B (boron) can be provided to form the p ⁺ -type diffusion layer 14 .

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

Furthermore, the method of applying the composition for p-type diffusion layer formation to the back surface of a silicon substrate is the same as the method of applying the composition for n-type diffusion layer formation to the silicon substrate mentioned above.

In the same manner as the thermal diffusion treatment of the n-type diffusion layer-forming composition described later, the p-type diffusion layer-forming composition applied to the back surface is subjected to thermal diffusion treatment, thereby forming a p ⁺ -type diffusion layer on the back surface. Layer 14. In addition, it is preferable that the thermal diffusion treatment of the composition for forming a p-type diffusion layer and the thermal diffusion treatment of the composition for forming an n-type diffusion layer be performed simultaneously.

Next, the p-type semiconductor substrate 10 on which the above-mentioned n-type diffusion layer-forming composition layer 11 is formed is subjected to thermal diffusion treatment at a temperature equal to or higher than the melting point of the glass powder in the composition, for example, 600°C to 1200°C. Through this thermal diffusion treatment, as shown in FIG. 1( 3 ), the donor element diffuses into the semiconductor substrate to form the n-type diffusion layer 12 . A known continuous furnace, batch furnace, etc. can be applied to the thermal diffusion treatment. In addition, the atmosphere in the furnace during the thermal diffusion treatment may be appropriately adjusted to air, oxygen, nitrogen, or the like.

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

A glass layer (not shown) such as phosphate glass is formed on the surface of the formed n-type diffusion layer 12 . Therefore, the phosphate glass is removed by etching. Any 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 used for etching. When using the etching method of immersing in an acid such as hydrofluoric acid, the immersion time is not particularly limited, and it is usually 0.5 minutes to 30 minutes, preferably 1 minute to 10 minutes.

In the forming method of the n-type diffused layer of the present invention shown in Fig. 1 (2) and Fig. 1 (3), the n-type diffused layer 12 is formed at the desired position without forming unnecessary n-type diffused layer 12 on the back or side. diffusion layer.

Therefore, in the method of forming the n-type diffusion layer by the gas phase reaction method widely used in the past, the side etching process for removing the unnecessary n-type diffusion layer formed on the side surface is necessary, but according to the manufacturing method of the present invention The method does not require a side etching process, thereby simplifying the process. Thus, with the production method of the present invention, a uniform n-type diffused layer of a desired shape can be formed in a desired position in a short period of time.

In addition, in the conventional manufacturing method, it is necessary to convert the unnecessary n-type diffusion layer formed on the back surface into a p-type diffusion layer. As the conversion method, the following method is adopted: coating the n-type diffusion layer on the back surface as Aluminum paste of Group 13 elements is fired to diffuse aluminum into the n-type diffusion layer, thereby converting the n-type diffusion layer into a p-type diffusion layer. In this method, in order to sufficiently convert the n-type diffusion layer into a p-type diffusion layer and further form a high-concentration electric field layer of a p ⁺ -type diffusion layer, a certain amount of aluminum is required, so the aluminum layer must be formed very thick. However, the coefficient of thermal expansion of aluminum is significantly different from that of silicon used as a substrate, and therefore a large internal stress is generated in the silicon substrate during firing and cooling, causing warpage of the silicon substrate.

This internal stress causes damage to the grain boundaries of the crystals, and there is a technical problem of increasing power loss. In addition, the warpage tends to damage the solar cell element during transport of the solar cell element in the module process or connection to copper wires called tab wires (TAB). In recent years, silicon substrates have become thinner due to improvements in slicing techniques, and solar cell elements tend to be more easily broken.

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

In addition, when using the manufacturing method of the present invention, the manufacturing method of the p ⁺ -type diffusion layer (high-concentration electric field layer) 14 on the back is not limited to the method of converting an n-type diffusion layer into a p-type diffusion layer based on aluminum, but also Any method can be used, and the degree of freedom of selection of the manufacturing method is expanded.

For example, it is preferable to apply a composition for forming a p-type diffused layer that uses glass powder containing an acceptor element instead of a glass powder containing a donor element and is configured in the same manner as the composition for forming an n-type diffused layer to the silicon substrate. The back side (the side opposite to the side to which the composition for forming an n-type diffusion layer was applied) is subjected to firing treatment to form a p ⁺ -type diffusion layer (high-concentration electric field layer) 14 on the back side.

In addition, as will be described later, the material used for the back electrode 20 is not limited to Group 13 aluminum, and Ag (silver) or Cu (copper), for example, can be used, and the thickness of the back electrode 20 can also be thinner than conventional ones. form.

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

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

In FIG. 1(5), on the antireflection film 16 on the surface (light-receiving surface), a metal paste for surface electrodes is applied by screen printing and dried to form a metal paste layer 17 for surface electrodes. The metal paste for surface electrodes contains (1) metal particles and (2) glass particles as essential components, and contains (3) a resin binder and (4) other additives as necessary.

Next, the back electrode metal paste layer 19 is also formed on the p ⁺ -type diffusion layer 14 on the back. As described above, in the present invention, the material and formation method of the back electrode metal paste layer 19 are not particularly limited. For example, a back electrode paste containing metal such as aluminum, silver, or copper may be applied and dried to form the back electrode metal paste layer 19 . At this time, a silver paste for forming a silver electrode may also be provided on a part of the back surface for connection between solar cell elements in the module process.

In FIG. 1 (6), the metal paste layer 17 for electrodes is fired, and the solar cell element is produced. If fired in the range of 600°C to 900°C for a few seconds to a few minutes, the antireflection film 16 as an insulating film is melted by the glass particles contained in the metal paste for electrodes on the surface side, and the p-type semiconductor The surface of the substrate 10 is also partially melted, and the metal particles (for example, silver particles) in the paste form a contact portion with the p-type semiconductor substrate 10 and solidify. Thereby, the formed surface electrode 18 and the p-type semiconductor substrate 10 are conducted. This is called fire through. In addition, on the back side, the back electrode metal paste of the back electrode metal paste layer 19 is similarly fired to form the back electrode 20 .

The shape of the surface electrode 18 will be described with reference to FIG. 2 . In addition, in FIG. 2 , 30 denotes a bus bar electrode, and 32 denotes a finger electrode. The surface electrode 18 includes a bus bar electrode 30 and finger electrodes 32 intersecting the bus bar electrode 30 . FIG. 2A is a plan view of a solar cell element in which the surface electrode 18 is formed to include a bus bar electrode 30 and a finger electrode 32 intersecting the bus bar electrode 30 as seen from the surface, and FIG. 2B is an enlarged view of a part of FIG. 2A stereogram.

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

In the above, a solar cell element in which an n-type diffusion layer is formed on the surface, a p ⁺ -type diffusion layer is formed on the back surface, and a surface electrode and a back electrode are provided on each layer has been described. The composition for forming an n-type diffused layer can also produce a back contact type solar cell element.

The back-contact type solar cell element is a solar cell element in which all electrodes are provided on the back surface to increase the area of the light-receiving surface. That is, in a back contact solar cell element, it is necessary to form both n-type diffusion sites and p ⁺ -type diffusion sites on the back surface to form a pn junction structure. Since the composition for forming an n-type diffusion layer of the present invention can form an n-type diffusion site at a specific site, it can be suitably applied to production of a back contact type solar cell element.

In the present invention, the use of the above-mentioned composition for forming an n-type diffusion layer when producing an n-type diffusion layer, and the use of the above-mentioned n-type diffusion layer when producing a solar cell element including the above-mentioned semiconductor substrate, n-type diffusion layer and electrode are also included. Use of layer-forming composition. As described above, by using the composition for forming an n-type diffused layer of the present invention, it is possible to obtain a uniform n-type diffused layer in a desired shape in a specific region in a short time without forming an unnecessary n-type diffused layer. , In addition, a solar cell element having such an n-type diffusion layer can be obtained without forming an unnecessary n-type diffusion layer.

Example

Hereinafter, examples of the present invention will be described more specifically, but the present invention is not limited by these examples. In addition, reagents were used for all chemicals unless otherwise specified. In addition, "%" means "mass %" unless otherwise stated. Furthermore, unless otherwise specified, "cm/s" means the "linear velocity" obtained by dividing the flow rate of gas flowing into the furnace by the cross-sectional area of the electric furnace.

[Example 1]

P ₂ O ₅ -SiO ₂ -CaO-based glass (softening temperature: 700°C, P ₂ O ₅ : 50% , SiO ₂ : 43%, CaO: 7%) powder 3 g, ethyl cellulose 2.1 g, and terpineol 24.9 g were mixed and pasted to prepare a composition for forming an n-type diffusion layer.

In addition, the glass particle shape was observed and judged using the Hitachi High-Technologies Co., Ltd. TM-1000 scanning electron microscope. The average particle diameter and d90 of glass were computed using the Beckman Coulter Co., Ltd. make LS13320 laser-scattering-diffraction method particle size distribution measuring apparatus (measurement wavelength: 632 nm). The softening temperature of the glass was determined from a differential thermal (DTA) curve using a DTG-60H differential thermal/thermogravimetric simultaneous measuring device manufactured by Shimadzu Corporation.

Then, the prepared paste was coated on the surface of the p-type silicon substrate by screen printing, and dried on a hot plate at 150° C. for 5 minutes. Next, hold in an oven set at 450° C. for 1.5 minutes to detach ethyl cellulose. Next, thermal diffusion treatment was performed by holding in an electric furnace set at 950°C for 10 minutes in an atmosphere of air flow (0.9cm/s), and then immersing the substrate in hydrofluoric acid to remove the glass layer. 5 minutes, then rinse with running water. Subsequently, drying is performed.

The sheet resistance of the surface on which the composition for forming an n-type diffusion layer was applied was 60 Ω/□, and P (phosphorus) diffused to form an n-type diffusion layer. In addition, the variation in sheet resistance value in the coated surface was σ=0.8, and a uniform n-type diffused layer was formed. On the other hand, the sheet resistance of the back surface was 1,000,000Ω/□ and could not be measured, and an n-type diffusion layer was not formed.

In addition, the sheet resistance was measured at 25°C by the four-probe method using a Loresta-EP MCP-T360 low resistivity meter manufactured by Mitsubishi Chemical Corporation.

In addition, σ represents a standard deviation, which is calculated by dividing the square root of the sum of the squares of the deviations of the sheet resistance values at 25 points in the coated surface by the number of data.

[Example 2]

An n-type diffused layer was formed in the same manner as in Example 1 except that the average particle diameter of the glass powder was 2 μm and d90 was 6.5 μm.

The sheet resistance of the surface on which the composition for forming an n-type diffusion layer was applied was 33Ω/□, and P (phosphorus) diffused to form an n-type diffusion layer. In addition, the variation in sheet resistance value in the coated surface was σ=0.5, and a uniform n-type diffused layer was formed. On the other hand, the sheet resistance of the back surface was 1,000,000Ω/□ and could not be measured, and an n-type diffusion layer was not formed.

[Example 3]

An n-type diffused layer was formed in the same manner as in Example 1 except that the average particle diameter of the glass powder was 0.7 μm and d90 was 3.4 μm.

The sheet resistance of the surface on which the composition for forming an n-type diffusion layer was applied was 25Ω/□, and P (phosphorus) diffused to form an n-type diffusion layer. In addition, the variation in sheet resistance value in the coated surface was σ=0.3, and a uniform n-type diffused layer was formed. On the other hand, the sheet resistance of the back surface was 1,000,000Ω/□ and could not be measured, and an n-type diffusion layer was not formed.

[Example 4]

P ₂ O ₅ -SiO ₂ -CaO-based glass (softening temperature 800°C, P ₂ O ₅ : 44%, SiO ₂ : 49%, CaO: 7%) powder 3g, ethyl cellulose 2.1g, and terpineol 24.9g were mixed and pasted to prepare A composition for forming an n-type diffused layer. Next, the prepared paste was coated on the surface of the p-type silicon substrate by screen printing, and dried on a hot plate at 150° C. for 5 minutes. Next, in an atmosphere of air flow (0.9cm/s), hold in an electric furnace set at 950°C for 10 minutes to perform thermal diffusion treatment, and then immerse the substrate in hydrofluoric acid for 5 minutes to remove the glass layer, Then wash with running water. Subsequently, drying is performed.

The sheet resistance of the surface on which the composition for forming an n-type diffusion layer was applied was 42 Ω/□, and P (phosphorus) diffused to form an n-type diffusion layer. In addition, the variation in sheet resistance value in the coated surface was σ=0.5, and a uniform n-type diffused layer was formed. On the other hand, the sheet resistance of the back surface was 1,000,000Ω/□ and could not be measured, and an n-type diffusion layer was not formed.

[Comparative example 1]

An n-type diffused layer was formed in the same manner as in Example 1 except that the average particle diameter of the glass powder was 8 μm and d90 was 50 μm.

The sheet resistance of the surface on which the composition for forming an n-type diffusion layer was applied was 120 Ω/□, and P (phosphorus) diffused to form an n-type diffusion layer. However, variation (σ=10.7) and non-uniformity were observed in the in-plane sheet resistance value.

[Comparative example 2]

An n-type diffused layer was formed in the same manner as in Example 1 except that the average particle diameter of the glass powder was 30 μm and d90 was 110 μm.

The sheet resistance of the surface on which the composition for forming an n-type diffusion layer was applied was 300 Ω/□, and P (phosphorus) diffused to form an n-type diffusion layer. However, variation (σ=24.9) and non-uniformity were observed in the in-plane sheet resistance value.

[Comparative example 3]

P ₂ O ₅ -SnO-based glass (softening temperature: 300°C, P ₂ O ₅ : 30%, SnO : 70%) powder 3 g, ethyl cellulose 2.1 g, and terpineol 24.9 g were mixed and pasted to prepare an n-type diffusion layer forming composition.

Next, the prepared paste was applied on the surface of the p-type silicon substrate in a thin line shape with a width of 120 μm by screen printing, and dried on a hot plate at 150° C. for 5 minutes. Next, in a nitrogen flow (0.9cm/s) atmosphere, hold in an electric furnace set at 950°C for 10 minutes to perform thermal diffusion treatment, and then immerse the substrate in hydrofluoric acid for 5 minutes to remove the glass layer, Then wash with running water. Subsequently, drying is performed.

The sheet resistance of the portion where the composition for forming an n-type diffused layer was applied in a thin line was 120 Ω/□, and P (phosphorus) was diffused to form an n-type diffused layer. In addition, since the width of the thin linear pattern to be applied was 400 μm, and the molten glass was dripped, selective diffusion to a specific portion could not be achieved.

[Comparative example 4]

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 using an automatic mortar mixing device. Paste was prepared to prepare a composition for forming an n-type diffusion layer.

Next, the prepared paste was coated on the surface of the p-type silicon substrate by screen printing, and dried on a hot plate at 150° C. for 5 minutes. Next, thermal diffusion treatment was performed by holding in an electric furnace set at 1000° C. for 10 minutes, and then the substrate was immersed in hydrofluoric acid for 5 minutes in order to remove the glass layer, followed by running water washing and drying.

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

[Comparative Example 5]

Using an automatic mortar mixing device, 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 isopropanol were mixed to prepare a solution, thereby preparing n Type diffusion layer composition.

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

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

All the content disclosed in the JP Patent application 2011-149249 for which it applied on July 5, 2011 is taken in into this specification by reference.

All documents, patent applications, and technical specifications described in this specification are incorporated by reference to the same extent as if each document, patent application, and technical specification were specifically and individually stated to be incorporated by reference. in the manual.

Claims (6)

1. a kind of n-type diffusion layer formation composition, it includes：Containing donor element, softening temperature is more than 500 DEG C and 900 Below DEG C, and average grain diameter is less than 5 μm of glass powder；And decentralized medium.

2. n-type diffusion layer formation composition according to claim 1, wherein, the d90 of the glass powder for 20 μm with Under.

3. n-type diffusion layer formation composition according to claim 1 or 2, wherein, the donor element is selected from phosphorus P And it is at least one kind of in antimony Sb.

4. according to n-type diffusion layer formation composition according to any one of claims 1 to 3, wherein, contain alms giver member The glass powder of element includes：Selected from by P₂O₃、P₂O₅And Sb₂O₃At least one kind of material containing donor element in the group constituted, with And selected from by SiO₂、K₂O、Na₂O、Li₂O、BaO、SrO、CaO、MgO、BeO、ZnO、PbO、CdO、SnO、ZrO₂And MoO₃Constituted Group at least one kind of glass ingredient material.

5. a kind of manufacture method of n-type diffusion layer, it includes：Entitle requires any one of 1~4 institute on a semiconductor substrate The process for the n-type diffusion layer formation composition stated；And heat diffusion treatment is implemented to the semiconductor substrate after the imparting Process.

6. a kind of manufacture method of solar cell device, it includes：Appoint on a semiconductor substrate in entitle requirement 1~4 The process of n-type diffusion layer formation composition described in one；Heat diffusion treatment is implemented to the semiconductor substrate after the imparting, So as to the process for forming n-type diffusion layer；And the process that electrode is formed in the n-type diffusion layer formed.