JP2010205965A - Method for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar battery manufacturing method for forming a heavily-doped diffusion layer and a lightly-doped diffusion layer at desired positions, in a stable manner. <P>SOLUTION: The solar battery manufacturing method includes a process for applying a dopant-diffusing agent containing first conductivity-type or second conductivity-type dopant to the front surface of a semiconductor substrate; a process for forming a diffusion-suppressing mask having an opening and/or a thin film and a thick film on the front surface of the dopant-diffusing agent; and a process for making the dopant diffuse to the front surface of the semiconductor substrate from the dopant diffusing agent with the diffusion suppressing mask arranged therein. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device capable of stably forming a high concentration dopant diffusion layer and a low concentration dopant diffusion layer at desired positions.

  In recent years, especially from the viewpoint of protecting the global environment, solar cells that convert solar energy into electrical energy have been rapidly expected as next-generation energy sources.

  There are various types of solar cells, such as those using compound semiconductors and those using organic materials. Currently, solar cells using silicon crystals are the mainstream. The most manufactured and sold solar cells now have an n-electrode on the surface on which sunlight is incident (light-receiving surface) and a p-electrode on the surface opposite to the light-receiving surface (back surface). Have been manufactured.

  For example, Patent Document 1 discloses a method for manufacturing a back electrode type solar cell in which an electrode is not formed on the light receiving surface of the solar cell, and an n electrode and a p electrode are formed only on the back surface.

  Hereinafter, a method for manufacturing a solar cell described in Patent Document 1 will be described with reference to the schematic cross-sectional views of FIGS.

  First, as shown in FIG. 7A, a low-concentration n-type dopant source 101 and a high-concentration n-type dopant source 102 are formed on the back surface of the silicon substrate 100 opposite to the surface on which the texture structure 112 is formed. The low-concentration p-type dopant source 103 and the high-concentration p-type dopant source 104 are formed by an inkjet method or a screen printing method.

  Next, as shown in FIG. 7B, the silicon substrate 100 is heat-treated to diffuse the n-type dopant from the low-concentration n-type dopant source 101 to the back surface of the silicon substrate 100 to a low concentration n. The n-type dopant diffusion layer 109 is formed, and the n-type dopant is diffused from the high-concentration n-type dopant source 102 to a high concentration to form the high-concentration n-type dopant diffusion layer 107. The low concentration p-type dopant diffusion layer 110 is formed by diffusing the p-type dopant at a low concentration, and the high concentration p-type dopant diffusion layer 108 is formed by diffusing the p-type dopant from the high concentration p-type dopant source 104 at a high concentration. Form.

International Publication No. 2007/081510 Pamphlet

  As shown in FIG. 7B, a low concentration is formed between the high concentration dopant diffusion layers of different conductivity types such as the high concentration n-type dopant diffusion layer 107 and the high concentration p-type dopant diffusion layer 108 on the back surface of the silicon substrate 100. Recent research has shown that when low-concentration dopant diffusion layers such as the n-type dopant diffusion layer 109 and the low-concentration p-type dopant diffusion layer 110 are formed, a back-electrode solar cell having high characteristics can be obtained. Yes.

  However, in the method described in Patent Document 1, the low-concentration n-type dopant source 109, the high-concentration n-type dopant source 107, the low-concentration p-type dopant source 110, and the high-concentration p-type dopant source 108 are subjected to an inkjet method or a screen. After the formation by the printing method, the silicon substrate 100 is heat-treated.

  Therefore, in the method described in Patent Document 1, dopants of different conductivity types diffuse to each other by outdiffusion (external diffusion) of the dopant from the above-described dopant source during the heat treatment of the silicon substrate 100. As shown in FIG. 7B, the diffusion of the dopant on the back surface of the high-concentration n-type dopant diffusion layer 107, the high-concentration p-type dopant diffusion layer 108, the low-concentration n-type dopant diffusion layer 109, and the low There is a problem that the concentration p-type dopant diffusion layer 110 cannot be stably formed at a desired position.

  The above problems are not limited to the back electrode type solar cell, but are common to the entire semiconductor device including the solar cell such as the back electrode type solar cell.

  In view of the above circumstances, an object of the present invention is to provide a method for manufacturing a semiconductor device capable of stably forming a high concentration dopant diffusion layer and a low concentration dopant diffusion layer at desired positions.

  According to the first aspect of the present invention, a step of applying a dopant diffusing agent containing a first conductivity type or second conductivity type dopant on the surface of the semiconductor substrate, and an opening on the surface of the dopant diffusing agent. It is possible to provide a method for manufacturing a semiconductor device, including a step of forming a diffusion suppression mask having a thick film portion and a step of diffusing a dopant from the dopant diffusing agent provided with the diffusion suppression mask to the surface of the semiconductor substrate. .

  Here, in the method of manufacturing the semiconductor device according to the first aspect of the present invention, in the step of diffusing the dopant, a high concentration dopant diffusion layer is formed in the surface region of the semiconductor substrate corresponding to the opening of the diffusion suppression mask, It is preferable to form a low-concentration dopant diffusion layer in the surface region of the semiconductor substrate corresponding to the thick film portion of the diffusion suppression mask.

In the method for manufacturing a semiconductor device according to the first aspect of the present invention, the dopant concentration of the high concentration dopant diffusion layer is preferably 1 × 10 ¹⁹ / cm ³ or more.

In the method for manufacturing a semiconductor device according to the first aspect of the present invention, the dopant concentration of the low-concentration dopant diffusion layer is preferably 1 × 10 ¹⁷ / cm ³ or more and less than 1 × 10 ¹⁹ / cm ³ .

  Moreover, according to the 2nd aspect of this invention, the process of apply | coating the dopant diffusing agent containing the dopant of a 1st conductivity type or a 2nd conductivity type on the surface of a semiconductor substrate, and a thin film on the surface of a dopant diffusing agent A method for manufacturing a semiconductor device, comprising: a step of forming a diffusion suppression mask having a portion and a thick film portion; and a step of diffusing a dopant from a dopant diffusing agent provided with the diffusion suppression mask to the surface of the semiconductor substrate. Can do.

  Here, in the method of manufacturing the semiconductor device according to the second aspect of the present invention, in the step of diffusing the dopant, a high concentration dopant diffusion layer is formed in the surface region of the semiconductor substrate corresponding to the thin film portion of the diffusion suppression mask, It is preferable to form a low-concentration dopant diffusion layer in the surface region of the semiconductor substrate corresponding to the thick film portion of the diffusion suppression mask.

In the method for manufacturing a semiconductor device according to the second aspect of the present invention, the dopant concentration of the high-concentration dopant diffusion layer is preferably 1 × 10 ¹⁹ / cm ³ or more.

In the method for manufacturing a semiconductor device according to the second aspect of the present invention, the dopant concentration of the low-concentration dopant diffusion layer is preferably 1 × 10 ¹⁷ / cm ³ or more and less than 1 × 10 ¹⁹ / cm ³ .

  Furthermore, according to the third aspect of the present invention, a step of applying a dopant diffusing agent containing a first conductivity type or second conductivity type dopant on the surface of the semiconductor substrate, and an opening on the surface of the dopant diffusing agent. A method for manufacturing a semiconductor device, comprising: a step of forming a diffusion suppression mask having a portion, a thin film portion, and a thick film portion; and a step of diffusing a dopant from the dopant diffusing agent provided with the diffusion suppression mask to the surface of the semiconductor substrate. Can be provided.

  Here, in the method of manufacturing the semiconductor device according to the third aspect of the present invention, in the step of diffusing the dopant, the high concentration dopant is applied to the surface region of the semiconductor substrate corresponding to at least one of the opening and the thin film portion of the diffusion suppressing mask. It is preferable to form a diffusion layer and form a low-concentration dopant diffusion layer in the surface region of the semiconductor substrate corresponding to the thick film portion of the diffusion suppression mask.

In the method for manufacturing a semiconductor device according to the third aspect of the present invention, the dopant concentration of the high-concentration dopant diffusion layer is preferably 1 × 10 ¹⁹ / cm ³ or more.

In the method for manufacturing a semiconductor device according to the third aspect of the present invention, the dopant concentration of the low-concentration dopant diffusion layer is preferably 1 × 10 ¹⁷ / cm ³ or more and less than 1 × 10 ¹⁹ / cm ³ .

  Moreover, in the manufacturing method of the semiconductor device of the 1st-3rd aspect of this invention, a dopant is given to the surface of a semiconductor substrate through a diffusion suppression mask from the dopant containing gas containing a 1st conductivity type or a 2nd conductivity type dopant. A step of diffusing may be further included.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the semiconductor device which can form a high concentration dopant diffusion layer and a low concentration dopant diffusion layer stably in a desired position can be provided.

(A)-(d) is typical sectional drawing illustrating the process of the experiment which this inventor performed. (A)-(k) is typical sectional drawing illustrating an example of the manufacturing method of the solar cell of this invention. It is a typical top view of the back surface of the back electrode type solar cell produced by the manufacturing method of the solar cell of this invention. (A)-(k) is typical sectional drawing illustrating another example of the manufacturing method of the solar cell of this invention. (A)-(j) is typical sectional drawing illustrating another example of the manufacturing method of the solar cell of this invention. (A)-(f) is typical sectional drawing illustrating another example of the manufacturing method of the solar cell of this invention. (A) And (b) is typical sectional drawing illustrating the manufacturing method of the solar cell of patent document 1. As shown in FIG.

  Embodiments of the present invention will be described below. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

<Inventor's Experiment>
1A to 1D are schematic cross-sectional views illustrating the process of an experiment performed by the present inventor. Here, the present inventor first prepares a silicon substrate 51 as shown in FIG. 1 (a), and subsequently contains boron on the surface of the silicon substrate 51 as shown in FIG. 1 (b). The paste 52 was applied and dried.

  Then, as shown in FIG. 1C, the present inventor has a thickness-existing portion (thick film portion 53a) and a non-existing portion (opening 53b) on the surface of the boron paste 52. After the silicon oxide film 53 patterned in this way was formed, the silicon substrate 51 after the formation of the silicon oxide film 53 was heat-treated.

  As a result, as shown by the arrow in FIG. 1D, boron, which is a p-type dopant, diffuses not only from the surface side of the silicon substrate 51 but also to the silicon oxide film 53 side from the boron paste 52, and the silicon oxide film 53. While the boron diffused to the side is absorbed by the thick film portion 53a of the silicon oxide film 53, the opening 53b of the silicon oxide film 53 has no target for the boron being absorbed to the silicon oxide film 53 side.

  Accordingly, the amount of boron diffused into the surface region of the silicon substrate 51 corresponding to the thick film portion 53a of the silicon oxide film 53 (the surface region of the silicon substrate 51 located below the thick film portion 53a of the silicon oxide film 53). In addition, the amount of boron diffused into the surface region of the silicon substrate 51 corresponding to the opening 53b of the silicon oxide film 53 (the surface region of the silicon substrate 51 located below the opening 53b of the silicon oxide film 53) increases.

  Then, in the surface region of the silicon substrate 51 corresponding to the thick film portion 53 a of the silicon oxide film 53, boron is diffused at a relatively low concentration to form a low concentration p-type dopant diffusion layer 54, and the silicon oxide film 53. A high-concentration p-type dopant diffusion layer 55 is formed in the surface region of the silicon substrate 51 corresponding to the opening 53b by diffusing boron at a relatively high concentration.

  From the above experiments, the present inventor has found that the low-concentration dopant diffusion layer and the high-concentration dopant diffusion layer can be separately formed on the surface of the semiconductor substrate by the film thickness of the diffusion suppression mask formed on the dopant diffusing agent. The present invention has been completed.

<Embodiment 1>
Below, with reference to typical sectional drawing of Fig.2 (a)-FIG.2 (k), an example of the manufacturing method of the solar cell of this invention is demonstrated.

  First, as shown in FIG. 2A, a semiconductor substrate 1 is prepared. Here, the semiconductor substrate 1 can be used without any particular limitation as long as it is a substrate made of a semiconductor. For example, a silicon substrate obtained by slicing from a silicon ingot can be used. Also, the conductivity type of the semiconductor substrate 1 is not particularly limited, and may have an n-type conductivity type, a p-type conductivity type, or any of n-type and p-type conductivity types. May not be included.

  When a silicon substrate is used as the semiconductor substrate 1, for example, a silicon substrate from which slice damage caused by slicing a silicon ingot is removed may be used. The removal of the slice damage can be performed, for example, by etching the surface of the silicon substrate after slicing with a mixed acid of hydrogen fluoride aqueous solution and nitric acid or an alkaline aqueous solution such as sodium hydroxide.

  Further, the size and shape of the semiconductor substrate 1 are not particularly limited. For example, the semiconductor substrate 1 may have a rectangular surface with a thickness of 100 μm to 300 μm and a side length of 100 mm to 200 mm. .

  Next, as shown in FIG. 2B, a first conductivity type dopant diffusing agent 2 containing a first conductivity type dopant is applied to a part of one surface of the semiconductor substrate 1.

  Here, as the first conductivity type dopant diffusing agent 2, one containing a first conductivity type dopant source can be used, and as the first conductivity type dopant source, when the first conductivity type is p-type. For example, a compound containing a boron atom and / or an aluminum atom such as boron oxide, boric acid, organoboron compound, boron-aluminum compound, organoaluminum compound or aluminum salt may be used alone or in combination of two or more. it can.

  The first conductivity type dopant diffusing agent 2 may contain a solvent and a thickener. Here, as the solvent, for example, ethylene glycol, methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve, diethyl cellosolve, cellosolve acetate, ethylene glycol monophenyl ether, methoxyethanol, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol, diethylene glycol Monomethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol acetate, triethyl glycol, triethyl Glycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol, liquid polyethylene glycol, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, 1-butoxyethoxypropanol, dipropyl glycol, dipropylene glycol Propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, polypropylene glycol, trimethylene glycol, butane dial, 1,5-pentane dial, hexylene glycol, glycerin, glyceryl acetate, glyceryl diacetate, glyceryl triacetate , Trimethylo Propyne, 1,2,6-hexanetriol, 1,2-propanediol, 1,5-pentanediol, octanediol, 1,2-butanediol, 1,4-butanediol, 1,3-butanediol, dioxane , Trioxane, tetrahydrofuran, tetrahydropyran, methylal, diethyl acetal, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, acetonyl acetone, diacetone alcohol, methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate alone or two These can be used in combination.

  Also, it is desirable to use ethyl cellulose, polyvinyl pyrrolidone or a mixture of both as thickeners, but various quality and properties of bentonite, generally inorganic rheological additives for various polar solvent mixtures, nitrocellulose and other Cellulose compounds, starch, gelatin, alginic acid, highly dispersible amorphous silicic acid (Aerosil®), polyvinyl butyral (Mowital®), sodium carboxymethylcellulose (vivistar), thermoplastic polyamide resin (Eurelon®) Trademark)), organic castor oil derivatives (Thixin R (registered trademark)), diamide wax (Thixatrol plus (registered trademark)), swollen polyacrylate (Rheolate (registered trademark)), polyether Urea - polyurethane, polyether - polyol like can also be used.

  Moreover, as a coating method of the 1st conductivity type dopant diffusing agent 2, for example, spray coating, coating using a dispenser, inkjet coating, screen printing, letterpress printing, intaglio printing, planographic printing, or the like can be used.

  Next, as shown in FIG. 2C, a diffusion suppression mask 3 is formed on the surface of the first conductivity type dopant diffusing agent 2 and on the surface of the semiconductor substrate 1. Here, the diffusion suppression mask 3 includes an opening 3b having no film thickness and a thick film portion 3a having a film thickness. In addition, in order to adjust the diffusion depth of the 2nd conductivity type dopant diffused from the 2nd conductivity type dopant diffusing agent 4 mentioned later, thin films, such as a silicon oxide film, may be formed on the opening part 3b.

  The film thickness of the thick film portion 3a of the diffusion suppression mask 3 is such that the surface region of the semiconductor substrate 1 corresponding to the thick film portion 3a of the diffusion suppression mask 3 (the semiconductor substrate 1 positioned below the thick film portion 3a of the diffusion suppression mask 3). The first conductive type dopant or the second conductive type dopant can be diffused into the surface region) to form a low-concentration dopant diffusion layer which will be described later.

  In addition, as diffusion suppression mask 3 (in this embodiment, thick film portion 3a of diffusion suppression mask 3), for example, a masking paste having an opening on the surface of semiconductor substrate 1 corresponding to the position where opening 2b is formed is used. After the application, the masking paste can be fired. As a coating method of the masking paste, for example, spray coating, coating using a dispenser, inkjet coating, screen printing, letterpress printing, intaglio printing, planographic printing, or the like can be used.

  In addition, as a masking paste, the thing containing a solvent, a thickener, a silicon oxide precursor, and / or a titanium oxide precursor, etc. can be used, for example. Moreover, as a masking paste, the thing which does not contain a thickener can also be used.

  Here, as the solvent, for example, ethylene glycol, methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve, diethyl cellosolve, cellosolve acetate, ethylene glycol monophenyl ether, methoxyethanol, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol, diethylene glycol Monomethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol acetate, triethyl glycol, triethyl Glycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol, liquid polyethylene glycol, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, 1-butoxyethoxypropanol, dipropyl glycol, dipropylene glycol Propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, polypropylene glycol, trimethylene glycol, butane dial, 1,5-pentane dial, hexylene glycol, glycerin, glyceryl acetate, glyceryl diacetate, glyceryl triacetate , Trimethylo Propyne, 1,2,6-hexanetriol, 1,2-propanediol, 1,5-pentanediol, octanediol, 1,2-butanediol, 1,4-butanediol, 1,3-butanediol, dioxane , Trioxane, tetrahydrofuran, tetrahydropyran, methylal, diethyl acetal, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, acetonyl acetone, diacetone alcohol, methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate alone or two These can be used in combination.

  Also, it is desirable to use ethyl cellulose, polyvinyl pyrrolidone or a mixture of both as thickeners, but various quality and properties of bentonite, generally inorganic rheological additives for various polar solvent mixtures, nitrocellulose and other Cellulose compounds, starch, gelatin, alginic acid, highly dispersible amorphous silicic acid (Aerosil®), polyvinyl butyral (Mowital®), sodium carboxymethylcellulose (vivistar), thermoplastic polyamide resin (Eurelon®) Trademark)), organic castor oil derivatives (Thixin R (registered trademark)), diamide wax (Thixatrol plus (registered trademark)), swollen polyacrylate (Rheolate (registered trademark)), polyether Urea - polyurethane, polyether - polyol like can also be used.

Examples of the silicon oxide precursor include a general formula R ′ _n Si (OR) _{4 -n} such as TEOS (tetraethyl orthosilicate) (R ′ is methyl, ethyl or phenyl, R is methyl, ethyl, n- A material represented by propyl or i-propyl, n is 0, 1 or 2) can be used.

Examples of the titanium oxide precursor include, in addition to Ti (OH) ₄ , a substance represented by R ′ _n Ti (OR) _4-n such as TPT (tetraisopropoxy titanium) (R ′ is methyl, ethyl). Alternatively, phenyl, R is methyl, ethyl, n-propyl or i-propyl, n is 0, 1 or 2), and TiCl ₄ , TiF ₄ , TiOSO _{4 and the} like are also included.

  Further, as the diffusion suppression mask 3 (in this embodiment, the thick film portion 3a of the diffusion suppression mask 3), for example, a silicon oxide film or silicon nitride is formed on the entire surface of the semiconductor substrate 1 by a CVD (Chemical Vapor Deposition) method or the like. A film, a titanium oxide film, or an aluminum oxide film can be formed by forming a single layer or a multilayered film and then removing part of the film. The removal of a part of the film made of the above-mentioned material is performed by, for example, forming a resist pattern having an opening on the surface of the above-described film using a photolithography technique on the surface of the above-described film. By a method of removing the above-mentioned film by etching or the like from the opening, or a method of etching and removing the diffusion suppression mask by applying an etching paste on the diffusion suppression mask corresponding to the position where the opening 3b is formed and then heating. Can be formed.

  In addition, as an etching paste, what contains phosphoric acid as an etching component and contains water, an organic solvent, and a thickener as components other than an etching component can be used, for example. As the organic solvent, for example, at least one kind of alcohol such as ethylene glycol, ether such as ethylene glycol monobutyl ether, ester such as propylene carbonate, or ketone such as N-methyl-2-pyrrolidone can be used. Moreover, as a thickener, at least 1 sort (s), such as a polymer which polymerized vinyl groups, such as polyamide resin, such as a cellulose, ethylcellulose, a cellulose derivative, nylon 6, or polyvinylpyrrolidone, can be used, for example.

  Next, as shown in FIG. 2D, a second conductivity type dopant diffusing agent 4 containing a second conductivity type dopant is applied so as to cover the surface portion of the semiconductor substrate 1 exposed from the diffusion suppression mask 3. To do.

  Here, as the second conductivity type dopant diffusing agent 4, a material containing a second conductivity type dopant source can be used. As the second conductivity type dopant source, when the second conductivity type is n-type, For example, a compound containing a phosphorus atom such as phosphate, phosphorus oxide, diphosphorus pentoxide, phosphoric acid or an organic phosphorus compound can be used alone or in combination of two or more.

  The second conductivity type dopant diffusing agent 4 may contain a solvent and a thickener. Examples of the solvent and the thickener that can be included in the second conductivity type dopant diffusing agent 4 include, for example, What was demonstrated as a solvent and a thickener which can be contained in 1 conductivity type dopant diffusing agent 2 can be used individually or in combination of 2 or more types.

  Moreover, as a coating method of the second conductivity type dopant diffusing agent 4, for example, spray coating, coating using a dispenser, inkjet coating, screen printing, letterpress printing, intaglio printing, or lithographic printing can be used.

  Next, the semiconductor substrate 1 is heat-treated to diffuse the first conductivity type dopant from the first conductivity type dopant diffusing agent 2 to the surface of the semiconductor substrate 1 as shown in FIG. The conductive type dopant diffusion layer 7 and the low concentration first conductive type dopant diffusion layer 9 are formed, and the second conductive type dopant is diffused from the second conductive type dopant diffusing agent 4 to the surface of the semiconductor substrate 1 to obtain the second high concentration second. Conductive dopant diffusion layer 8 and low-concentration second conductive dopant diffusion layer 10 are formed.

  Here, by the heat treatment of the semiconductor substrate 1, the first conductivity type dopant diffuses not only from the surface of the semiconductor substrate 1 but also to the thick film portion 3 a of the diffusion suppression mask 3 from the first conductivity type dopant diffusing agent 2.

  As a result, the first conductive dopant diffuses not only from the surface of the semiconductor substrate 1 but also to the thick film portion 3a of the diffusion suppressing mask 3 from the first conductive dopant diffusing agent 2 with which the thick film portion 3a of the diffusion suppressing mask 3 is in contact. Then, the low concentration first conductivity type dopant diffusion having a relatively low first conductivity type dopant concentration in the surface region of the semiconductor substrate 1 corresponding to the thick film portion 3a of the diffusion suppressing mask 3 is absorbed by the thick film portion 3a. Layer 9 will be formed.

  On the other hand, the first conductivity type dopant diffused from the first conductivity type dopant diffusing agent 2 in the opening 3 b of the diffusion suppression mask 3 is not absorbed by the thick film portion 3 a of the diffusion suppression mask 3 and diffuses to the surface of the semiconductor substrate 1. Therefore, in the surface region of the semiconductor substrate 1 corresponding to the opening 3 b of the diffusion suppression mask 3, the high concentration first conductivity type dopant diffusion having a first conductivity type dopant concentration higher than that of the low concentration first conductivity type dopant diffusion layer 9. Layer 7 will be formed.

  Further, by the heat treatment of the semiconductor substrate 1 described above, the second conductivity type dopant is diffused from the second conductivity type dopant diffusing agent 4 to the surface of the semiconductor substrate 1 through the opening 3 b of the diffusion suppression mask 3, whereby the high concentration second conductivity. The low-concentration second conductivity type is formed by the diffusion of the second conductivity type dopant to the surface of the semiconductor substrate 1 from the second conductivity type dopant diffusing agent 4 through the thick film portion 3a of the diffusion suppression mask 3. A dopant diffusion layer 10 is formed.

  Here, since the diffusion of the second conductivity type dopant from the second conductivity type dopant diffusing agent 4 is suppressed by the thick film portion 3 a of the diffusion suppression mask 3, the diffusion of the semiconductor substrate 1 through the thick film portion 3 a of the diffusion suppression mask 3 is suppressed. The amount of dopant diffusing on the surface is smaller than the amount of dopant diffusing on the surface of the semiconductor substrate 1 through the opening 3 b of the diffusion suppressing mask 3.

  As a result, a high-concentration second conductivity type dopant diffusion layer 8 is formed in the surface region of the semiconductor substrate 1 corresponding to the opening 3 b of the diffusion suppression mask 3, and the semiconductor substrate corresponding to the thick film portion 3 a of the diffusion suppression mask 3. The low-concentration second conductivity type dopant diffusion layer 10 is formed in the surface region of 1. Needless to say, the high concentration second conductivity type dopant diffusion layer 8 has a second conductivity type dopant concentration higher than that of the low concentration second conductivity type dopant diffusion layer 10.

  In addition, although the conditions of the heat processing of said semiconductor substrate 1 are not specifically limited, a high concentration dopant diffusion layer (the high concentration 1st conductivity type dopant diffusion layer 7 and the high concentration 2nd conductivity type dopant diffusion layer 8) and a low concentration dopant diffusion From the viewpoint of stably forming the layers (low-concentration first conductivity type dopant diffusion layer 9 and low-concentration second conductivity type dopant diffusion layer 10), the semiconductor substrate 1 is, for example, 20 at a temperature of 850 ° C. or more and 1000 ° C. or less. It can be heated for not less than 50 minutes and not more than 50 minutes.

  Next, as shown in FIG. 2F, the first conductivity type dopant diffusing agent 2, the diffusion suppression mask 3 and the second conductivity type dopant diffusing agent 4 on the surface of the semiconductor substrate 1 are removed. Thereby, on the surface of the semiconductor substrate 1, the high concentration first conductivity type dopant diffusion layer 7, the high concentration second conductivity type dopant diffusion layer 8, the low concentration first conductivity type dopant diffusion layer 9, and the low concentration second conductivity type dopant. Each surface of the diffusion layer 10 is exposed.

  Next, as shown in FIG. 2 (g), the high concentration first conductivity type dopant diffusion layer 7, the high concentration second conductivity type dopant diffusion layer 8, the low concentration first conductivity type dopant diffusion layer 9 of the semiconductor substrate 1 and A passivation film 11 is formed on the surface where the low-concentration second conductivity type dopant diffusion layer 10 is exposed.

  Here, as the passivation film 11, for example, a silicon oxide film, a silicon nitride film, or a stacked body of a silicon oxide film and a silicon nitride film formed by a plasma CVD method or the like can be used.

  Next, as shown in FIG. 2H, a texture structure 12 made of, for example, pyramidal irregularities is formed on the surface of the semiconductor substrate 1 opposite to the side on which the passivation film 11 is formed.

  Here, the texture structure 12 can be formed, for example, by etching the surface of the semiconductor substrate 1. When the semiconductor substrate 1 is made of a silicon substrate, the surface of the semiconductor substrate 1 is etched using, for example, a solution obtained by adding isopropyl alcohol to an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide, for example, 70 ° C. or higher and 80 ° C. or lower. The etching can be performed by etching the surface of the semiconductor substrate 1 using an etching solution heated to a high temperature.

  Next, as shown in FIG. 2 (i), an antireflection film 13 is formed on the texture structure 12 on the surface of the semiconductor substrate 1. As the antireflection film 13, for example, a silicon oxide film, a silicon nitride film, or a stacked body of a silicon oxide film and a silicon nitride film formed by a plasma CVD method or the like can be used.

  Next, as shown in FIG. 2 (j), a contact hole is formed by removing a part of the passivation film 11 of the semiconductor substrate 1, and the high-concentration first conductivity type dopant diffusion layer 7 and the high concentration are formed from the contact hole. Each surface of the second conductivity type dopant diffusion layer 8 is exposed.

  Here, the contact hole is formed by, for example, etching the passivation film 11 from the opening of the resist pattern after forming a resist pattern having an opening on the passivation film 11 at a portion corresponding to the location where the contact hole is formed using photolithography technology. It can be formed by a method of removing the passivation film 11 by etching or removing the passivation film 11 by applying an etching paste to the portion of the passivation film 11 corresponding to the contact hole forming portion and then heating. In addition, as an etching paste, the thing similar to the etching paste demonstrated above can be used.

  Next, as shown in FIG. 2 (k), the first conductivity type electrode 14 electrically connected to the high concentration first conductivity type dopant diffusion layer 7 through the contact hole, and the high concentration second conductivity type dopant. A second conductivity type electrode 15 electrically connected to the diffusion layer 8 is formed.

  Here, as the first conductivity type electrode 14 and the second conductivity type electrode 15, for example, an electrode made of a metal such as silver can be used.

  As described above, the back electrode type solar cell can be manufactured by the method for manufacturing a solar cell in the present embodiment.

  In FIG. 3, the typical top view of the back surface of the back electrode type solar cell produced by the manufacturing method of the solar cell in this Embodiment is shown.

  Here, on the back surface of the back electrode type solar cell, as shown in FIG. 3, a plurality of strip-shaped first conductivity type electrodes 14 and a plurality of strip-shaped second conductivity type electrodes 15 are alternately arranged one by one. All the first conductivity type electrodes 14 are electrically connected to one strip-shaped first conductivity type current collecting electrode 14a, and all the second conductivity type electrodes 14 are arranged at intervals. 15 is electrically connected to one strip-shaped second-conductivity-type collecting electrode 15a. In addition, two circular alignment marks 20 are respectively arranged on the back surface of the semiconductor substrate 1 diagonally to the back surface of the semiconductor substrate 1.

  Further, on the back surface of the semiconductor substrate 1, a high-concentration first conductivity type dopant diffusion layer 7 is disposed below each of the plurality of strip-shaped first conductivity type electrodes 14, and the plurality of strip-shaped second conductivity type electrodes. The high-concentration second-conductivity-type dopant diffusion layer 8 is disposed below each of the shapes of the high-concentration first-conductivity-type dopant diffusion layer 7 and the high-concentration second-conductivity-type dopant diffusion layer 8. The size is not particularly limited. For example, the high-concentration first conductivity type dopant diffusion layer 7 and the high-concentration second conductivity type dopant diffusion layer 8 are formed in a strip shape along each of the first conductivity type electrode 10 and the second conductivity type electrode 11. Alternatively, the first conductive type electrode 14 and the second conductive type electrode 15 may be formed in a dot shape in contact with each part.

  2A to 2K, for convenience of explanation, one high-concentration first conductivity type dopant diffusion layer 7 and one high-concentration second conductivity type dopant diffusion layer 8 are provided on the semiconductor substrate 1. However, in practice, a plurality of high-concentration first conductivity type dopant diffusion layers 7 and a plurality of high-concentration second conductivity type dopant diffusion layers 8 may be formed. Needless to say.

  In the method for manufacturing a solar cell according to the present embodiment, which is an example of the present invention, a diffusion suppression mask 3 having a thick film portion 3a and an opening 3b and a dopant diffusing agent (first conductivity type dopant diffusing agent 2 and second By installing the conductive dopant diffusing agent 4), a high concentration dopant diffusion layer (high concentration first conductive type dopant diffusion layer 7 and high concentration second conductivity type dopant diffusion layer 8) and a low concentration dopant diffusion layer (low concentration first layer). The conductive dopant diffusion layer 9 and the low-concentration second conductive dopant diffusion layer 10) are formed at desired positions.

  Therefore, since the high-concentration dopant diffusion layer and the low-concentration dopant diffusion layer can be separately formed by changing the film thickness of the diffusion suppression mask 3, the high-concentration dopant diffusion layer is compared with the method described in Patent Document 1 above. In addition, the low-concentration dopant diffusion layer can be stably formed at a desired position.

  Further, in the method for manufacturing a solar cell according to the present embodiment, patterning (diffusion) of the diffusion suppression mask 3 for forming the high concentration first conductivity type dopant diffusion layer 7 and the high concentration second conductivity type dopant diffusion layer 8 is performed. It is not necessary to carry out the step (formation of the opening 3b of the suppression mask 3) once each time when forming the high-concentration first conductivity type dopant diffusion layer 7 and the high-concentration second conductivity type dopant diffusion layer 8 (two times in total). Therefore, the manufacturing process can be simplified.

  Moreover, in the manufacturing method of the solar cell of this Embodiment, the high concentration 1st conductivity type dopant diffusion layer 7, the high concentration 2nd conductivity type dopant diffusion layer 8, the low concentration 1st conductivity type dopant diffusion layer 9, and the low concentration Since the heat treatment for forming the second conductivity type dopant diffusion layer 10 need only be performed once, the manufacturing process can be simplified and thermal damage to the semiconductor substrate 1 and the like due to the heat treatment can be effectively suppressed. it can.

  Further, as in the method of manufacturing the solar cell of the present embodiment, by providing an opening in the diffusion suppression mask, a high concentration dopant diffusion layer and a low concentration dopant diffusion layer, which are diffusion regions having a concentration difference, are separately formed. Becomes easy.

  When the first conductivity type is p-type, for example, a p-type dopant such as boron can be used as the first conductivity type dopant, and when the second conductivity type is n-type, As the second conductivity type dopant, for example, an n-type dopant such as phosphorus can be used.

Further, from the viewpoint of making the back electrode type solar cell have high characteristics, the dopant concentration of the high concentration dopant diffusion layer (the high concentration first conductivity type dopant diffusion layer 7 and the high concentration second conductivity type dopant diffusion layer 8) is set to 1 ×. More preferably, it is 10 ¹⁹ / cm ³ or more.

Further, from the viewpoint of making the back electrode type solar cell have high characteristics, the dopant concentration of the low concentration dopant diffusion layer (the low concentration first conductivity type dopant diffusion layer 9 and the low concentration second conductivity type dopant diffusion layer 10) is set to 1 ×. is preferably set to 10 ¹⁷ / cm ³ or more 1 × 10 ¹⁹ / cm less than ^3, and more preferably set to 5 × 10 ¹⁷ / cm ³ or more 1 × 10 ¹⁸ / cm ³ or less.

  2A to 2K, for convenience of explanation, one high-concentration first conductivity type dopant diffusion layer 7 and one high-concentration second conductivity type dopant diffusion layer 8 are provided in the semiconductor substrate 1. However, in practice, a plurality of high-concentration first conductivity type dopant diffusion layers 7 and a plurality of high-concentration second conductivity type dopant diffusion layers 8 may be formed. Needless to say.

<Embodiment 2>
The present embodiment is characterized in that the diffusion suppression mask 3 includes an opening 3b, a thin film portion 3c, and a thick film portion 3a having a thickness larger than that of the thin film portion 3c. Others are the same as in the first embodiment.

  Hereinafter, a method for manufacturing the solar cell in the present embodiment will be described with reference to schematic cross-sectional views of FIGS. 4A to 4K, for convenience of explanation, one high-concentration first conductivity type dopant diffusion layer 7 and one high-concentration second conductivity type dopant diffusion layer 8 are provided in the semiconductor substrate 1. However, in practice, a plurality of high-concentration first conductivity type dopant diffusion layers 7 and a plurality of high-concentration second conductivity type dopant diffusion layers 8 may be formed. Needless to say.

  First, as shown in FIG. 4A, a semiconductor substrate 1 is prepared. Subsequently, as shown in FIG. 4B, a first conductive type dopant containing a first conductivity type dopant in a part of the surface of the semiconductor substrate 1 is prepared. 1-conductivity type dopant diffusing agent 2 is applied. Here, the first conductivity type dopant diffusing agent 2 can be applied by, for example, the same method as the first conductivity type dopant diffusing agent 2 in the first embodiment.

  Next, as shown in FIG. 4C, a diffusion suppression mask 3 is formed on the surface of the first conductivity type dopant diffusing agent 2 and on the surface of the semiconductor substrate 1. Here, diffusion suppression mask 3 in the present embodiment can be formed, for example, by the same method as diffusion suppression mask 3 in the first embodiment.

  The film thickness of the thin film portion 3c of the diffusion suppressing mask 3 is not particularly limited as long as the dopant of the first conductivity type or the second conductivity type can be diffused to form a high-concentration dopant diffusion layer described later. .

  Next, as illustrated in FIG. 4D, a second conductivity type dopant diffusing agent 4 containing a second conductivity type dopant is applied so as to cover the thin film portion 3 c of the diffusion suppression mask 3. Here, the second conductivity type dopant diffusing agent 4 can be applied by, for example, the same method as the second conductivity type dopant diffusing agent 4 in the first embodiment.

  Next, as shown in FIG. 4E, the semiconductor substrate 1 is heat-treated, so that the first conductive type dopant diffusing agent 2 and the second conductive type dopant diffusing agent 4 have a first conductive property on the surface of the semiconductor substrate 1 respectively. The high-concentration first conductive-type dopant diffusion layer 7, the high-concentration second-conductivity-type dopant diffusion layer 8, the low-concentration first-conductivity-type dopant diffusion layer 9, and the low-concentration first A two-conductivity type dopant diffusion layer 10 is formed.

  Here, by the heat treatment of the semiconductor substrate 1, the first conductivity type dopant diffuses not only from the surface of the semiconductor substrate 1 but also to the thick film portion 3 a of the diffusion suppression mask 3 from the first conductivity type dopant diffusing agent 2.

  As a result, the first conductive dopant diffuses not only from the surface of the semiconductor substrate 1 but also to the thick film portion 3a of the diffusion suppressing mask 3 from the first conductive dopant diffusing agent 2 with which the thick film portion 3a of the diffusion suppressing mask 3 is in contact. Then, the low concentration first conductivity type dopant diffusion having a relatively low first conductivity type dopant concentration in the surface region of the semiconductor substrate 1 corresponding to the thick film portion 3a of the diffusion suppressing mask 3 is absorbed by the thick film portion 3a. Layer 9 will be formed.

  On the other hand, the first conductivity type dopant diffused from the first conductivity type dopant diffusing agent 2 in the opening 3 b of the diffusion suppression mask 3 is diffused to the semiconductor substrate 1 without being absorbed by the thick film portion 3 a of the diffusion suppression mask 3. The high-concentration first-conductivity-type dopant diffusion layer 7 having a higher first-conductivity-type dopant concentration than the low-concentration first-conductivity-type dopant diffusion layer 9 in the surface region of the semiconductor substrate 1 corresponding to the opening 3b of the diffusion suppression mask 3. Will be formed.

  Further, by the heat treatment of the semiconductor substrate 1, the second conductivity type dopant is diffused from the second conductivity type dopant diffusing agent 4 to the surface of the semiconductor substrate 1 through the thin film portion 3 c of the diffusion suppression mask 3, whereby the high concentration second conductivity. The low-concentration second conductivity type is formed by the diffusion of the second conductivity type dopant to the surface of the semiconductor substrate 1 from the second conductivity type dopant diffusing agent 4 through the thick film portion 3a of the diffusion suppression mask 3. The dopant diffusion layer 10 is formed.

  Here, since the diffusion of the second conductivity type dopant from the second conductivity type dopant diffusing agent 4 is suppressed by the thick film portion 3 a of the diffusion suppression mask 3, the diffusion of the semiconductor substrate 1 through the thick film portion 3 a of the diffusion suppression mask 3 is suppressed. The amount of dopant diffusing on the surface is smaller than the amount of dopant diffusing on the surface of the semiconductor substrate 1 through the thin film portion 3 c of the diffusion suppression mask 3.

  As a result, a high-concentration second conductivity type dopant diffusion layer 8 is formed in the surface region of the semiconductor substrate 1 corresponding to the thin film portion 3c of the diffusion suppression mask 3, and the semiconductor substrate corresponding to the thick film portion 3a of the diffusion suppression mask 3 The low-concentration second conductivity type dopant diffusion layer 10 is formed in the surface region of 1. Needless to say, the high concentration second conductivity type dopant diffusion layer 8 has a second conductivity type dopant concentration higher than that of the low concentration second conductivity type dopant diffusion layer 10.

  Next, as shown in FIG. 4 (f), the semiconductor substrate is removed by removing the first conductivity type dopant diffusing agent 2, the diffusion suppression mask 3 and the second conductivity type dopant diffusing agent 4 on the surface of the semiconductor substrate 1. 1 on the surface of the high concentration first conductivity type dopant diffusion layer 7, the high concentration second conductivity type dopant diffusion layer 8, the low concentration first conductivity type dopant diffusion layer 9 and the low concentration second conductivity type dopant diffusion layer 10. To expose each.

  Next, as shown in FIG. 4G, the high concentration first conductivity type dopant diffusion layer 7, the high concentration second conductivity type dopant diffusion layer 8, the low concentration first conductivity type dopant diffusion layer 9 of the semiconductor substrate 1 and A passivation film 11 is formed on the surface where the low-concentration second conductivity type dopant diffusion layer 10 is exposed.

  Next, as shown in FIG. 4 (h), a texture structure 12 made of, for example, pyramidal irregularities is formed on the surface of the semiconductor substrate 1 opposite to the side on which the passivation film 11 is formed. ), An antireflection film 13 is formed on the texture structure 12 on the surface of the semiconductor substrate 1.

  Next, as shown in FIG. 4J, a part of the passivation film 11 of the semiconductor substrate 1 is removed to form a contact hole, and the high-concentration first conductivity type dopant diffusion layer 7 and the high concentration are formed from the contact hole. Each surface of the second conductivity type dopant diffusion layer 8 is exposed.

  Next, as shown in FIG. 4 (k), the first conductivity type electrode 14 electrically connected to the high concentration first conductivity type dopant diffusion layer 7 through the contact hole, and the high concentration second conductivity type dopant. A second conductivity type electrode 15 electrically connected to the diffusion layer 8 is formed.

  As described above, the back electrode type solar cell can be manufactured by the method for manufacturing a solar cell in the present embodiment.

  In the method for manufacturing a solar cell according to the present embodiment, which is an example of the present invention, a diffusion suppression mask 3 having an opening 3b, a thin film portion 3c, and a thick film portion 3a having a larger film thickness than the thin film portion 3c. And the dopant diffusing agent (the first conductivity type dopant diffusing agent 2 and the second conductivity type dopant diffusing agent 4) are installed, so that the high concentration dopant diffusion layer (the high concentration first conductivity type dopant diffusion layer 7 and the high concentration second conductivity type). The dopant diffusion layer 8) and the low concentration dopant diffusion layer (the low concentration first conductivity type dopant diffusion layer 9 and the low concentration second conductivity type dopant diffusion layer 10) are formed at desired positions.

  Therefore, since the high-concentration dopant diffusion layer and the low-concentration dopant diffusion layer can be separately formed by changing the film thickness of the diffusion suppression mask 3, the high-concentration dopant diffusion layer is compared with the method described in Patent Document 1 above. In addition, the low-concentration dopant diffusion layer can be stably formed at a desired position.

  Further, in the method for manufacturing a solar cell according to the present embodiment, patterning (diffusion) of the diffusion suppression mask 3 for forming the high concentration first conductivity type dopant diffusion layer 7 and the high concentration second conductivity type dopant diffusion layer 8 is performed. The step of forming the opening 3b and the thin film portion 3c of the suppression mask 3 is performed once each time when forming the high-concentration first conductivity type dopant diffusion layer 7 and the high-concentration second conductivity type dopant diffusion layer 8 (two times in total). Since it is not necessary to carry out, the manufacturing process can be simplified.

  Moreover, in the manufacturing method of the solar cell of this Embodiment, the high concentration 1st conductivity type dopant diffusion layer 7, the high concentration 2nd conductivity type dopant diffusion layer 8, the low concentration 1st conductivity type dopant diffusion layer 9, and the low concentration Since the heat treatment for forming the second conductivity type dopant diffusion layer 10 need only be performed once, the manufacturing process can be simplified and thermal damage to the semiconductor substrate 1 and the like due to the heat treatment can be effectively suppressed. it can.

  Further, as in the method of manufacturing the solar cell of the present embodiment, by providing an opening in the diffusion suppression mask, a high concentration dopant diffusion layer and a low concentration dopant diffusion layer, which are diffusion regions having a concentration difference, are separately formed. Becomes easy.

  Further, in the method of manufacturing the solar cell of the present embodiment, for example, when the first conductivity type dopant is boron and the second conductivity type dopant is phosphorus by the thin film portion 3c of the diffusion suppression mask 3, etc. Thus, when the diffusion depth of the second conductivity type dopant diffusing from the second conductivity type dopant diffusing agent 4 becomes deeper than the diffusion depth of the first conductivity type dopant diffusing from the first conductivity type dopant diffusing agent 2. However, since the diffusion of the second conductivity type dopant can be suppressed by the thin film portion 3c, the depth of the first conductivity type dopant diffusion layer 7 and the high concentration second conductivity type dopant can be adjusted by adjusting the thickness of the thin film portion 3c. The depth of the diffusion layer 8 can be made comparable.

  Since the description other than the above in the present embodiment is the same as that in the first embodiment, the description thereof is omitted.

<Embodiment 3>
In the present embodiment, the second conductivity type dopant-containing gas containing phosphorus as the second conductivity type dopant is used instead of the coating diffusion by the second conductivity type dopant diffusing agent for the diffusion of the second conductivity type dopant on the surface of the semiconductor substrate. It is characterized by carrying out by gas phase diffusion by.

  Hereinafter, a method for manufacturing the solar cell in the present embodiment will be described with reference to the schematic cross-sectional views of FIGS. 5A to 5J, for convenience of explanation, one high-concentration first conductivity type dopant diffusion layer 7 and one high-concentration second conductivity type dopant diffusion layer 8 are provided on the semiconductor substrate 1. However, in practice, a plurality of high-concentration first conductivity type dopant diffusion layers 7 and a plurality of high-concentration second conductivity type dopant diffusion layers 8 may be formed. Needless to say.

  First, as shown in FIG. 5A, a semiconductor substrate 1 which is an n-type silicon substrate is prepared. Subsequently, as shown in FIG. First conductivity type dopant diffusing agent 2 containing boron which is a type dopant is applied. Here, application | coating of the 1st conductivity type dopant diffusing agent 2 containing a boron can be apply | coated by the method similar to the 1st conductivity type dopant diffusing agent 2 in Embodiment 1-2, for example.

  Next, as shown in FIG. 5C, a diffusion suppression mask 3 made of a silicon oxide film is formed on the surface of the first conductivity type dopant diffusing agent 2 containing boron and on the surface of the semiconductor substrate 1. Here, the diffusion suppression mask 3 made of the silicon oxide film in the present embodiment can be formed, for example, by the same method as the diffusion suppression mask 3 in the first and second embodiments.

  Next, as shown in FIG. 5D, the semiconductor substrate 1 is heat-treated, so that boron as the first conductivity type dopant is added to the surface of the semiconductor substrate 1 from the first conductivity type dopant diffusing agent 2 containing boron. A high-concentration first conductive type dopant diffusion layer 7 and a low-concentration first conductive type dopant diffusion layer 9 that are p-type dopant diffusion layers are formed by diffusion, and a second conductive type dopant-containing gas 17 containing phosphorus is added. By flowing, phosphorus which is the second conductivity type dopant is diffused on the surface of the semiconductor substrate 1, and the high concentration second conductivity type dopant diffusion layer 8 and the low concentration second conductivity type dopant diffusion layer 10 which are n type dopant diffusion layers. Form.

  In addition, the diffusion process of phosphorus which is the second conductivity type dopant using the second conductivity type dopant containing gas 17 containing phosphorus may be performed in the same process as the diffusion process of boron which is the first conductivity type dopant, You may carry out continuously immediately before and / or just after the diffusion process of boron which is the first conductivity type dopant.

  Here, the semiconductor substrate 1 is formed from the second conductive dopant containing gas 17 containing phosphorus through the opening 3b of the diffusion suppressing mask 3 by vapor phase diffusion using the second conductive dopant containing gas 17 containing phosphorus. The second conductivity type dopant diffusion layer 8 is formed by diffusing phosphorus as the second conductivity type dopant on the surface of the film, and the thick film of the diffusion suppression mask 3 from the second conductivity type dopant containing gas 17 containing phosphorus. The low concentration second conductivity type dopant diffusion layer 10 is formed by diffusing phosphorus as the second conductivity type dopant on the surface of the semiconductor substrate 1 through the portion 3a.

  By the heat treatment of the semiconductor substrate 1, boron as the first conductivity type dopant is diffused from the first conductivity type dopant diffusing agent 2 containing boron, and the semiconductor substrate 1 corresponding to the opening 3 b of the diffusion suppression mask 3 is diffused. A high concentration first conductivity type dopant diffusion layer 7 is formed in the surface region, and a low concentration first conductivity type dopant diffusion layer 9 is formed in the surface region of the semiconductor substrate 1 corresponding to the thick film portion 3 a of the diffusion suppression mask 3. Is done.

  That is, also in the present embodiment, boron, which is the first conductivity type dopant, diffuses not only from the surface of the semiconductor substrate 1 but also from the first conductivity type dopant diffusing agent 2 containing boron by the heat treatment of the semiconductor substrate 1 described above. It also diffuses into the thick film portion 3 a of the suppression mask 3.

  As a result, the first conductive type dopant diffusing agent 2 in contact with the thick film portion 3a of the diffusion suppression mask 3 causes boron, which is the first conductive type dopant, not only to the surface of the semiconductor substrate 1, but also to the thick film portion 3a of the diffusion suppression mask 3. The low-concentration first-conductivity-type dopant diffusion layer having a relatively low boron concentration in the surface region of the semiconductor substrate 1 corresponding to the thick film portion 3a of the diffusion suppression mask 3 is also diffused and absorbed by the thick film portion 3a. 9 will be formed.

  On the other hand, boron, which is the first conductivity type dopant that diffuses from the first conductivity type dopant diffusing agent 2 in the opening 3 b of the diffusion suppression mask 3, is not absorbed by the thick film portion 3 a of the diffusion suppression mask 3, and the surface of the semiconductor substrate 1. In the surface region of the semiconductor substrate 1 corresponding to the opening 3b of the diffusion suppression mask 3, the high concentration first conductivity type dopant diffusion layer having a higher boron concentration than the low concentration first conductivity type dopant diffusion layer 9 is formed. 7 will be formed.

  In addition, the second conductivity type dopant-containing gas 17 containing phosphorus described above causes the second conductivity type to enter the surface of the semiconductor substrate 1 from the second conductivity type dopant-containing gas 17 containing phosphorus through the opening 3 b of the diffusion suppression mask 3. A high-concentration second conductivity type dopant diffusion layer 8 is formed by diffusing phosphorus, which is a dopant, from the second conductivity type dopant-containing gas 17 containing phosphorus through the thick film portion 3a of the diffusion suppression mask 3, and The low concentration second conductivity type dopant diffusion layer 10 is formed by diffusing phosphorus as the second conductivity type dopant on the surface.

  Here, since diffusion of phosphorus, which is the second conductivity type dopant, from the second conductivity type dopant-containing gas 17 containing phosphorus is suppressed by the thick film portion 3a of the diffusion suppression mask 3, the diffusion suppression mask 3 The amount of phosphorus diffusing to the surface of the semiconductor substrate 1 through the thick film portion 3a is smaller than the amount of phosphorus diffusing to the surface of the semiconductor substrate 1 through the opening 3b of the diffusion suppressing mask 3.

  As a result, a high-concentration second conductivity type dopant diffusion layer 8 is formed in the surface region of the semiconductor substrate 1 corresponding to the opening 3 b of the diffusion suppression mask 3, and the semiconductor substrate corresponding to the thick film portion 3 a of the diffusion suppression mask 3. The low-concentration second conductivity type dopant diffusion layer 10 is formed in the surface region of 1. Needless to say, the high concentration second conductivity type dopant diffusion layer 8 has a higher phosphorus concentration than the low concentration second conductivity type dopant diffusion layer 10.

As the second conductivity type dopant-containing gas 17 containing phosphorus, for example, it is possible to use a gas containing phosphorus, such as POCl _3.

  Next, as shown in FIG. 5 (e), the first conductive type dopant diffusing agent 2 and the diffusion suppression mask 3 on the surface of the semiconductor substrate 1 are removed, so that a high concentration first is formed on the surface of the semiconductor substrate 1. The surfaces of the conductive dopant diffusion layer 7, the high concentration second conductivity type dopant diffusion layer 8, the low concentration first conductivity type dopant diffusion layer 9, and the low concentration second conductivity type dopant diffusion layer 10 are exposed.

  Next, as shown in FIG. 5 (f), the high concentration first conductivity type dopant diffusion layer 7, the high concentration second conductivity type dopant diffusion layer 8, the low concentration first conductivity type dopant diffusion layer 9 of the semiconductor substrate 1 and A passivation film 11 is formed on the surface where the low-concentration second conductivity type dopant diffusion layer 10 is exposed.

  Next, as shown in FIG. 5G, a texture structure 12 made of, for example, pyramidal irregularities is formed on the surface of the semiconductor substrate 1 opposite to the side on which the passivation film 11 is formed. ), An antireflection film 13 is formed on the texture structure 12 on the surface of the semiconductor substrate 1.

  Next, as shown in FIG. 5I, a part of the passivation film 11 of the semiconductor substrate 1 is removed to form a contact hole, and the high-concentration first conductivity type dopant diffusion layer 7 and the high concentration are formed from the contact hole. Each surface of the second conductivity type dopant diffusion layer 8 is exposed.

  Next, as shown in FIG. 5 (j), the first conductivity type electrode 14 electrically connected to the high concentration first conductivity type dopant diffusion layer 7 through the contact hole, and the high concentration second conductivity type dopant. A second conductivity type electrode 15 electrically connected to the diffusion layer 8 is formed.

  As described above, the back electrode type solar cell can be manufactured by the method for manufacturing a solar cell in the present embodiment.

  In the method for manufacturing a solar cell according to the present embodiment which is an example of the present invention, installation of a diffusion suppression mask 3 having an opening 3b and a thick film portion 3a on one surface of a semiconductor substrate 1 which is an n-type silicon substrate. The high-concentration dopant diffusion layer (high-concentration first-conductivity-type dopant diffusion) is obtained by installing the first-conductivity-type dopant diffusing agent 2 containing boron and vapor-phase diffusion using the second-conductivity-type dopant-containing gas 17 containing phosphorus. The layer 7 and the high concentration second conductivity type dopant diffusion layer 8) and the low concentration dopant diffusion layer (the low concentration first conductivity type dopant diffusion layer 9 and the low concentration second conductivity type dopant diffusion layer 10) are formed at desired positions. It will be.

  Therefore, since the high-concentration dopant diffusion layer and the low-concentration dopant diffusion layer can be separately formed by changing the film thickness of the diffusion suppression mask 3, the high-concentration dopant diffusion layer is compared with the method described in Patent Document 1 above. In addition, the low-concentration dopant diffusion layer can be stably formed at a desired position.

  Further, in the method for manufacturing a solar cell according to the present embodiment, patterning (diffusion) of the diffusion suppression mask 3 for forming the high concentration first conductivity type dopant diffusion layer 7 and the high concentration second conductivity type dopant diffusion layer 8 is performed. It is not necessary to carry out the step (formation of the opening 3b of the suppression mask 3) once each time when forming the high-concentration first conductivity type dopant diffusion layer 7 and the high-concentration second conductivity type dopant diffusion layer 8 (two times in total). Therefore, the manufacturing process can be simplified.

  Moreover, in the manufacturing method of the solar cell of this Embodiment, the high concentration 1st conductivity type dopant diffusion layer 7, the high concentration 2nd conductivity type dopant diffusion layer 8, the low concentration 1st conductivity type dopant diffusion layer 9, and the low concentration Since the heat treatment for forming the second conductivity type dopant diffusion layer 10 need only be performed once, the manufacturing process can be simplified and thermal damage to the semiconductor substrate 1 and the like due to the heat treatment can be effectively suppressed. it can.

  Further, as in the method of manufacturing the solar cell of the present embodiment, by providing an opening in the diffusion suppression mask, a high concentration dopant diffusion layer and a low concentration dopant diffusion layer, which are diffusion regions having a concentration difference, are separately formed. Becomes easy.

  In addition, since the description other than the above in the present embodiment is the same as that in the first and second embodiments, the description thereof is omitted.

<Embodiment 4>
This embodiment is characterized in that a solar cell having a structure in which electrodes are provided on the light receiving surface and the back surface of a semiconductor substrate, not a back electrode type solar cell, is produced.

  Hereinafter, a method for manufacturing the solar cell in the present embodiment will be described with reference to the schematic cross-sectional views of FIGS.

  First, as shown in FIG. 6A, an n-type semiconductor substrate 71 is prepared. Subsequently, as shown in FIG. 6B, a p-type dopant such as boron is applied on the surface of the n-type semiconductor substrate 71. The contained p-type dopant diffusing agent 72 is applied. In addition, as a coating method of the p-type dopant diffusing agent 72, for example, spray coating, coating using a dispenser, inkjet coating, screen printing, letterpress printing, intaglio printing, or lithographic printing can be used.

  Next, as shown in FIG. 6C, a diffusion suppression mask 3 having an opening 3 b and a thick film portion 3 a is formed on the surface of the p-type dopant diffusing agent 72. Here, the diffusion suppression mask 3 can be formed in the same manner as in the first to third embodiments. Moreover, as a coating method of the p-type dopant diffusing agent 72, for example, a method similar to the above can be used.

  Next, as shown in FIG. 6D, the n-type semiconductor substrate 71 is heat-treated to diffuse the n-type dopant from the n-type dopant diffusing agent 72 to the surface of the p-type semiconductor substrate 71, thereby forming the n-type semiconductor. A low concentration n-type dopant diffusion layer 76 and a high concentration n-type dopant diffusion layer 75 are formed on the surface of the substrate 71, respectively.

  Here, due to the heat treatment of the n-type semiconductor substrate 71 described above, the n-type dopant is diffused at a relatively high concentration in the surface region of the p-type semiconductor substrate 71 corresponding to the opening 3b of the diffusion suppression mask 3, thereby increasing the concentration. A p-type dopant diffusion layer 75 is formed, and the n-type dopant diffuses at a relatively low concentration in the surface region of the n-type semiconductor substrate 71 corresponding to the thick film portion 3a of the diffusion suppression mask 3, whereby a low-concentration p-type dopant is formed. A diffusion layer 76 is formed.

  That is, also in this embodiment, by the heat treatment of the n-type semiconductor substrate 71, the p-type dopant diffuses from the p-type dopant diffusing agent 72 not only on the surface of the n-type semiconductor substrate 71 but also on the thick film portion of the diffusion suppression mask 3. It also diffuses to 3a.

  Thereby, the p-type dopant diffuses not only from the surface of the n-type semiconductor substrate 71 but also to the thick film portion 3a of the diffusion suppression mask 3 from the p-type dopant diffusing agent 72 in contact with the thick film portion 3a of the diffusion suppression mask 3. Since it is absorbed by the thick film portion 3a, a low-concentration p-type dopant diffusion layer 76 having a relatively low p-type dopant concentration is formed in the surface region of the n-type semiconductor substrate 71 corresponding to the thick film portion 3a of the diffusion suppression mask 3. Will be.

  On the other hand, the p-type dopant diffused from the p-type dopant diffusing agent 72 in the opening 3b of the diffusion suppression mask 3 is not absorbed by the thick film portion 3a of the diffusion suppression mask 3 but diffuses to the surface of the n-type semiconductor substrate 71. A high-concentration p-type dopant diffusion layer 75 having a higher p-type dopant concentration than the low-concentration p-type dopant diffusion layer 76 is formed in the surface region of the n-type semiconductor substrate 71 corresponding to the opening 3 b of the diffusion suppression mask 3. It will be.

  Next, as shown in FIG. 6E, by removing the diffusion suppression mask 3 and the p-type dopant diffusing agent 72 from the surface of the n-type semiconductor substrate 71, a high concentration p is formed on the surface of the n-type semiconductor substrate 71. The surfaces of the p-type dopant diffusion layer 75 and the low-concentration p-type dopant diffusion layer 76 are exposed.

  Next, as shown in FIG. 6F, a p-electrode 77 is formed on the high-concentration p-type dopant diffusion layer 75 formed on the surface that becomes the light-receiving surface of the n-type semiconductor substrate 71, and the n-type semiconductor substrate. An n electrode 78 is formed on the back surface of 71.

  Here, as the p electrode 77 and the n electrode 78, for example, an electrode made of a metal such as silver can be used.

  As described above, a solar cell having a structure in which electrodes are provided on the light-receiving surface and the back surface of a semiconductor substrate can be manufactured by the method for manufacturing a solar cell in the present embodiment.

  In the method for manufacturing a solar cell according to the present embodiment which is an example of the present invention, a high concentration p-type dopant is obtained by installing a diffusion suppression mask 3 having an opening 3b and a thick film portion 3a and a p-type dopant diffusing agent 72. The diffusion layer 75 and the low-concentration p-type dopant diffusion layer 76 are formed at desired positions.

  Therefore, since the high-concentration p-type dopant diffusion layer 75 and the low-concentration p-type dopant diffusion layer 76 can be separately formed by changing the film thickness of the diffusion suppression mask 3, compared with the method described in Patent Document 1 above. The high-concentration p-type dopant diffusion layer 75 and the low-concentration p-type dopant diffusion layer 76 can be stably formed at desired positions.

  In the method for manufacturing a solar cell according to the present embodiment, the manufacturing process is performed because the heat treatment for forming the high-concentration p-type dopant diffusion layer 75 and the low-concentration p-type dopant diffusion layer 76 is performed only once. In addition to simplification, thermal damage to the n-type semiconductor substrate 71 and the like due to heat treatment can be effectively suppressed.

  Further, as in the method of manufacturing the solar cell of the present embodiment, by providing an opening in the diffusion suppression mask, a high concentration dopant diffusion layer and a low concentration dopant diffusion layer, which are diffusion regions having a concentration difference, are separately formed. Becomes easy.

  In the present embodiment, an antireflection film, a texture structure, a passivation film, and the like may be formed on the n-type semiconductor substrate 71 as in the first to third embodiments.

  6A to 6F show that only one high-concentration p-type dopant diffusion layer 75 is formed on the n-type semiconductor substrate 71 for convenience of explanation. Needless to say, a plurality of high-concentration p-type dopant diffusion layers 75 may be formed.

  The concept of the semiconductor device of the present invention includes all semiconductor devices including solar cells. Further, the concept of the solar cell of the present invention includes not only a back electrode type solar cell having a configuration in which both a p-type electrode and an n-type electrode are formed only on one surface (back surface) of a semiconductor substrate, but also MWT. (Metal Wrap Through) cells (solar cells with a configuration in which a part of electrodes are arranged in through holes provided in a semiconductor substrate) and so-called back contact solar cells (current from the back side opposite to the light receiving surface of the semiconductor substrate) Solar cells having a structure in which the electrodes are taken out) and double-sided electrode type solar cells manufactured by forming electrodes on the light-receiving surface and the back surface of the semiconductor substrate, respectively.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  According to the present invention, a method for manufacturing a semiconductor device capable of stably forming a high concentration dopant diffusion layer and a low concentration dopant diffusion layer at a desired position can be provided. The present invention can be suitably used for the manufacture of a double-sided electrode type solar cell having an electrode on the back surface and a back-side electrode type solar cell having an electrode only on the back surface of the semiconductor substrate.

  DESCRIPTION OF SYMBOLS 1 Semiconductor substrate, 2 1st conductivity type dopant diffusing agent, 3 Diffusion suppression mask, 3a Thick film part, 3b Opening part, 3c Thin film part, 4 2nd conductivity type dopant diffusing agent, 7 High concentration 1st conductivity type dopant diffusion layer 8 High concentration second conductivity type dopant diffusion layer 9 Low concentration first conductivity type dopant diffusion layer 10 Low concentration second conductivity type dopant diffusion layer 11 Passivation film 12 Texture structure 13 Antireflection film 14 First Conductive type electrode, 14a First conductive type collector electrode, 15 Second conductive type electrode, 15a Second conductive type collector electrode, 17 Second conductive type dopant-containing gas, 20 Alignment mark, 51,100 Silicon Substrate, 52 boron paste, 53 silicon oxide film, 53a thick film part, 53b opening, 54 low concentration p-type dopant diffusion layer, 55 high concentration Type dopant diffusion layer, 71 n type semiconductor substrate, 72 p type dopant diffusing agent, 75 high concentration p type dopant diffusion layer, 76 low concentration p type dopant diffusion layer, 77 p electrode, 78 n electrode, 101 low concentration n type dopant Source 102 high concentration n-type dopant source 103 low concentration p-type dopant source 104 high concentration p-type dopant source 107 high concentration n-type dopant diffusion layer 112 texture structure 108 high concentration p-type dopant diffusion layer 109 low Concentration n-type dopant diffusion layer, 110 low-concentration p-type dopant diffusion layer.

Claims (13)

Applying a dopant diffusing agent containing a dopant of the first conductivity type or the second conductivity type on the surface of the semiconductor substrate;
Forming a diffusion suppression mask having an opening and a thick film portion on the surface of the dopant diffusing agent;
And a step of diffusing the dopant from the dopant diffusing agent provided with the diffusion suppression mask to the surface of the semiconductor substrate.   In the step of diffusing the dopant, a high concentration dopant diffusion layer is formed in a surface region of the semiconductor substrate corresponding to the opening of the diffusion suppressing mask, and the semiconductor substrate corresponding to the thick film portion of the diffusion suppressing mask 2. The method of manufacturing a semiconductor device according to claim 1, wherein a low-concentration dopant diffusion layer is formed in the surface region of the semiconductor device. The method for manufacturing a semiconductor device according to claim 2, wherein a dopant concentration of the high-concentration dopant diffusion layer is 1 × 10 ¹⁹ / cm ³ or more. 4. The method of manufacturing a semiconductor device according to claim 2, wherein a dopant concentration of the low-concentration dopant diffusion layer is 1 × 10 ¹⁷ / cm ³ or more and less than 1 × 10 ¹⁹ / cm ³ . Applying a dopant diffusing agent containing a dopant of the first conductivity type or the second conductivity type on the surface of the semiconductor substrate;
Forming a diffusion suppression mask having a thin film portion and a thick film portion on the surface of the dopant diffusing agent;
And a step of diffusing the dopant from the dopant diffusing agent provided with the diffusion suppression mask to the surface of the semiconductor substrate.   In the step of diffusing the dopant, a high concentration dopant diffusion layer is formed in a surface region of the semiconductor substrate corresponding to the thin film portion of the diffusion suppression mask, and the semiconductor substrate corresponding to the thick film portion of the diffusion suppression mask 6. The method of manufacturing a semiconductor device according to claim 5, wherein a low-concentration dopant diffusion layer is formed in the surface region of the semiconductor device. The method for manufacturing a semiconductor device according to claim 6, wherein a dopant concentration of the high-concentration dopant diffusion layer is 1 × 10 ¹⁹ / cm ³ or more. 8. The method of manufacturing a semiconductor device according to claim 6, wherein a dopant concentration of the low-concentration dopant diffusion layer is 1 × 10 ¹⁷ / cm ³ or more and less than 1 × 10 ¹⁹ / cm ³ . Applying a dopant diffusing agent containing a dopant of the first conductivity type or the second conductivity type on the surface of the semiconductor substrate;
Forming a diffusion suppression mask having an opening, a thin film portion, and a thick film portion on the surface of the dopant diffusing agent;
And a step of diffusing the dopant from the dopant diffusing agent provided with the diffusion suppression mask to the surface of the semiconductor substrate.   In the step of diffusing the dopant, a high-concentration dopant diffusion layer is formed in a surface region of the semiconductor substrate corresponding to at least one of the opening and the thin film portion of the diffusion suppression mask, and the thick film of the diffusion suppression mask The method for manufacturing a semiconductor device according to claim 9, wherein a low-concentration dopant diffusion layer is formed in a surface region of the semiconductor substrate corresponding to a portion. The method for manufacturing a semiconductor device according to claim 10, wherein a dopant concentration of the high-concentration dopant diffusion layer is 1 × 10 ¹⁹ / cm ³ or more. 12. The method of manufacturing a semiconductor device according to claim 10, wherein a dopant concentration of the low-concentration dopant diffusion layer is 1 × 10 ¹⁷ / cm ³ or more and less than 1 × 10 ¹⁹ / cm ³ .   13. The method according to claim 1, further comprising a step of diffusing the dopant from the dopant-containing gas containing the dopant of the first conductivity type or the second conductivity type to the surface of the semiconductor substrate through the diffusion suppression mask. A method for manufacturing a semiconductor device according to any one of the above.

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