JP2010267787A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device by which a decrease in characteristics of the semiconductor device can be stably suppressed. <P>SOLUTION: The method of manufacturing the semiconductor device includes the processes of: forming a wettability improving film on a surface of a semiconductor substrate; coating a surface of the wettability improving film with a dopant diffusing agent containing dopants of a first conductivity type and a second conductivity type; and forming a dopant diffusion layer by diffusing the dopants in the semiconductor substrate from the dopant diffusing agent. <P>COPYRIGHT: (C)2011,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 that can stably suppress deterioration in characteristics of the semiconductor device.

In recent years, development of clean energy has been demanded due to problems of depletion of energy resources and global environmental problems such as an increase in atmospheric CO ₂ , and solar power generation using solar cells is particularly new among semiconductor devices. It has been developed and put into practical use as an energy source and is on the path of development.

  Conventionally, a solar cell forms a pn junction by diffusing an impurity having a conductivity type opposite to that of a silicon substrate, for example, on a light receiving surface of a monocrystalline or polycrystalline silicon substrate, Double-sided electrode type solar cells manufactured by forming electrodes on the back surface opposite to the light receiving surface are mainly used. In a double-sided electrode type solar cell, it is also common to increase the output by the back surface field effect by diffusing impurities of the same conductivity type as the silicon substrate at a high concentration on the back surface of the silicon substrate.

  Research and development is also underway for a back electrode type solar cell in which an electrode is not formed on the light receiving surface of a silicon substrate but an electrode is formed only on the back surface (see, for example, Patent Document 1).

  Hereinafter, the manufacturing method of the back electrode type solar cell described in Patent Document 1 will be described with reference to the schematic cross-sectional views of FIGS. 10 (a) to 10 (e).

  First, as shown in FIG. 10A, the texture structure 108 is formed on one surface of the silicon substrate 100.

  Next, as shown in FIG. 10B, an oxide layer 109 is formed on the texture structure 108 on the surface of the silicon substrate 100.

  Next, as shown in FIG. 10C, a p-type dopant is contained on the back surface of the silicon substrate 100 having the p-type or n-type conductivity type, which is the surface opposite to the side where the texture structure 108 is formed. A p-type doping paste 103 to be applied and an n-type doping paste 104 containing an n-type dopant are applied at a predetermined interval.

  Next, as illustrated in FIG. 10D, an oxide layer 102 is formed so as to cover the p-type doping paste 103 and the n-type doping paste 104 on the back surface of the silicon substrate 100.

  Thereafter, by heat-treating the silicon substrate 100, the p-type dopant is diffused from the p-type doping paste 103 to the back surface of the silicon substrate 100, and the n-type dopant is diffused from the n-type doping paste 104, thereby FIG. ), A p-type dopant diffusion layer 105 and an n-type dopant diffusion layer 106 are formed on the back surface of the silicon substrate 100, respectively.

  Then, the metallized portion 110 is formed on the p-type dopant diffusion layer 105 on the back surface of the silicon substrate 100, and the metallized portion 111 is formed on the n-type dopant diffusion layer 106, whereby the back surface described in Patent Document 1 is obtained. An electrode type solar cell is produced.

JP 2008-78665 A

  In order to improve the characteristics of the back electrode type solar cell described in Patent Document 1, the p-type dopant diffusion layer 105 and the n-type dopant diffusion layer 106 on the back surface of the silicon substrate 100 may be formed with fine line widths, respectively. preferable. Therefore, for example, as shown in the schematic plan view of FIG. 11A, the p-type doping paste 103 and the n-type doping paste 104 are preferably applied with a fine line width w.

  However, since the silicon substrate 100 is hydrophobic, when the hydrophilic p-type doping paste 103 and the hydrophilic n-type doping paste 104 are applied to the surface of the silicon substrate 100, respectively, The p-type doping paste 103 and the n-type doping paste 104 are repelled. Therefore, in the method of manufacturing the back electrode type solar cell described in Patent Document 1, for example, as shown in the schematic plan view of FIG. 11B, the p-type doping paste 103 applied to the surface of the silicon substrate 100 and In some cases, the n-type doping paste 104 was divided.

  In the case where the p-type dopant diffusion layer 105 and the n-type dopant diffusion layer 106 are formed from the p-type doping paste 103 and the n-type doping paste 104 that are divided in this way, respectively, Since the p-type dopant diffusion layer 105 and the n-type dopant diffusion layer 106 are not formed in the divided portion of the n-type doping paste 104, there is a problem that the characteristics of the back electrode type solar cell are greatly deteriorated.

  This problem is not limited to the back electrode type solar cell, but is a problem common to other semiconductor devices.

  In view of the above circumstances, an object of the present invention is to provide a method of manufacturing a semiconductor device that can stably suppress a decrease in characteristics of the semiconductor device.

  The present invention includes a step of forming a wettability improving film on a surface of a semiconductor substrate, and a step of applying a dopant diffusing agent containing a first conductivity type or second conductivity type dopant on the surface of the wettability improving film; And a step of forming a dopant diffusion layer by diffusing the dopant from the dopant diffusing agent into the semiconductor substrate.

  Here, in the method for manufacturing a semiconductor device of the present invention, it is preferable that the contact angle of the dopant diffusing agent after coating is 5 ° or more and 30 ° or less.

  In the method for manufacturing a semiconductor device of the present invention, it is preferable that the wettability improving film is formed to a thickness of 50 nm or less in the step of forming the wettability improving film.

  In the method for manufacturing a semiconductor device of the present invention, it is preferable that the wettability improving film is hydrophilic.

  Furthermore, in the method for manufacturing a semiconductor device of the present invention, in the step of applying the dopant diffusing agent, the dopant diffusing agent is preferably applied so that the minimum line width is 300 μm or less.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the semiconductor device which can suppress the fall of the characteristic of a semiconductor device stably can be provided.

(A)-(l) is typical sectional drawing illustrating the manufacturing method of the solar cell of Embodiment 1 of this invention. It is a typical expanded sectional view of an example of the 1st conductivity type dopant diffusion agent apply | coated on the surface of the 1st wettability improvement film | membrane of the surface of the semiconductor substrate shown in FIG.1 (c). It is a typical expanded sectional view of an example of the 2nd conductivity type dopant diffusion agent apply | coated on the surface of the 2nd wettability improvement film | membrane of the surface of the semiconductor substrate shown in FIG.1 (g). It is a typical top view of an example of the back of a back electrode type solar cell produced by the manufacturing method of the solar cell of the present invention. It is a typical top view of other examples of the back of a back electrode type solar cell produced by the manufacturing method of the solar cell of the present invention. It is a typical top view of another example of the back surface of the back electrode type solar cell produced by the manufacturing method of the solar cell of this invention. (A)-(h) is typical sectional drawing illustrating the manufacturing method of the solar cell of Embodiment 2 of this invention. (A)-(l) is typical sectional drawing illustrating the manufacturing method of the solar cell of Embodiment 3 of this invention. (A)-(f) is typical sectional drawing illustrating the manufacturing method of the solar cell of Embodiment 4 of this invention. (A)-(e) is typical sectional drawing illustrating the manufacturing method of the conventional back electrode type solar cell. (A) is a schematic plan view of an ideal application state of a p-type doping paste and an n-type doping paste, and (b) is a schematic view of an actual application state of a p-type doping paste and an n-type doping paste. It is a top view.

  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.

<Embodiment 1>
Hereinafter, an example of a method for manufacturing a solar cell, which is an example of the semiconductor device of the present invention, will be described with reference to the schematic cross-sectional views of FIGS. 1 (a) to 1 (l).

  First, as shown in FIG. 1A, a semiconductor substrate 1 on which a texture structure 8 made of, for example, pyramidal irregularities is formed 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. Further, the semiconductor substrate 1 may have an n-type conductivity type or a p-type conductivity type.

  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. .

  The texture structure 8 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.

  Although the texture structure 8 may not be formed, the texture structure 8 is preferably formed in order to increase the amount of sunlight incident on the semiconductor substrate 1.

  Next, as shown in FIG. 1B, the first wettability improving film 2 is formed on the back surface, which is the surface opposite to the surface of the semiconductor substrate 1 on which the texture structure 8 is formed.

  Here, the first wettability improving film 2 is used without any particular limitation as long as it can stably suppress the later-described dopant diffusing agent applied on the surface of the semiconductor substrate 1 from being repelled. be able to.

  In particular, when the semiconductor substrate 1 is a hydrophobic substrate such as a silicon substrate, it is preferable to use a hydrophilic film as the first wettability improving film 2. In this case, when a hydrophilic dopant diffusing agent is applied directly on the back surface of the hydrophobic semiconductor substrate 1, the dopant diffusing agent is stably prevented from being repelled on the back surface of the semiconductor substrate 1. This is because it can be done.

  Here, as the hydrophilic first wettability improving film 2, for example, a silicon oxide film, a silicon nitride film, or a film having an OH group (hydroxyl group) on the surface is formed as a single layer or a combination of a plurality of these films. And the like can be used.

  The thickness of the first wettability improving film 2 is preferably 50 nm or less. When the thickness of the first wettability improving film 2 is 50 nm or less, the dopant tends to diffuse into the semiconductor substrate 1 from the dopant diffusing agent through the first wettability improving film 2.

  The thickness of the first wettability improving film 2 is preferably 1 nm or more. When the thickness of the first wettability improving film 2 is 1 nm or more, the wettability improving effect due to the formation of the first wettability improving film 2 tends to be easily obtained.

  The first wettability improving film 2 can be formed by, for example, a CVD (Chemical Vapor Deposition) method or a thermal oxidation method.

  Next, as shown in FIG. 1C, the first conductivity type dopant diffusing agent 3 containing the first conductivity type dopant is applied on the surface of the first wettability improving film 2 on the back surface of the semiconductor substrate 1. . The 1st conductivity type dopant diffusing agent 3 can be apply | coated to the strip | belt shape extended | stretched from the surface side of FIG.1 (c) to a back surface side, for example.

  Here, as a coating method of the first conductivity type dopant diffusing agent 3, for example, spray coating, coating using a dispenser, inkjet coating, screen printing, letterpress printing, intaglio printing, planographic printing, or the like can be used.

  Moreover, as the 1st conductivity type dopant diffusing agent 3, what contains a 1st conductivity type dopant source can be used, and when a 1st conductivity type is n type as a 1st conductivity type dopant source, 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, and the first conductivity type is p-type. In this case, for example, boron oxide and boric acid, organoboron compound, boron-aluminum compound, organoaluminum compound or a compound containing boron atom and / or aluminum atom such as aluminum salt alone or in combination of two or more kinds Can be used.

  Moreover, as components other than the 1st conductivity type dopant source of the 1st conductivity type dopant diffusing agent 3, what contains a solvent, a silane compound, and a thickener can be used, for example. In addition, as the first conductivity type dopant diffusing agent 3, one not containing a thickener can also be used.

  Here, examples of the solvent include water, methanol, ethanol, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, 1,2-propanediol, 1,4-butanediol, , 3-butanediol, dioxane, trioxane, tetrahydrofuran, tetrahydropyranmethylal, diethyl acetal, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, acetonyl acetone, diacetone alcohol, methyl formate, ethyl formate, propyl formate, methyl acetate, acetic acid Examples include ethyl, acetic anhydride, N-methylpyrrolidone and the like. A solvent can be used individually by 1 type or in combination of 2 or more types.

  Moreover, as a silane compound, what is represented by the following general formula (1) can be used, for example.

R ¹ _n Si (OR ² ) _4-n (1)
In the above general formula (1), R ¹ represents a methyl group, an ethyl group or a phenyl group. In the general formula (1), R ² represents a linear or branched alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, or a butyl group. Moreover, in said general formula (1), n shows the integer of 0-4.

  Examples of the silane compound represented by the general formula (1) include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, and salts thereof (such as tetraethylorthosilicate). A silane compound can be used individually by 1 type or in combination of 2 or more types.

  Examples of the thickener include castor oil, bentonite, nitrocellulose, ethyl cellulose, polyvinyl pyrrolidone, starch, gelatin, alginic acid, amorphous silicic acid, polyvinyl butyral, sodium carboxymethyl cellulose, polyamide resin, organic castor oil derivative, Examples include diamide wax, swollen polyacrylate, polyether urea-polyurethane, and polyether-polyol. A thickener can be used individually by 1 type or in combination of 2 or more types.

FIG. 2 is a schematic enlarged cross-sectional view of an example of the first conductivity type dopant diffusing agent 3 applied on the surface of the first wettability improving film 2 on the back surface of the semiconductor substrate 1 shown in FIG. Show. Here, the contact angle θ ₁ of the first conductivity type dopant diffusing agent 3 with respect to the first wettability improving film 2 is preferably 5 ° or more and 30 ° or less, and more preferably 10 ° or more and 20 ° or less. .

When the contact angle θ ₁ of the first conductivity type dopant diffusing agent 3 with respect to the first wettability improving film 2 is less than 5 °, the line width of the first conductivity type dopant diffusing agent 3 is too wide, and a desired pattern is obtained. And / or the line width may not be drawn. Moreover, when said contact angle (theta) ₁ is larger than 30 degrees, while there exists a possibility that the 1st conductivity type dopant diffusing agent 3 may be disconnected, there exists a possibility that the line edge of the 1st conductivity type dopant diffusing agent 3 may be disturbed.

In addition, when the contact angle θ _{1 of} the first conductivity type dopant diffusing agent 3 with respect to the first wettability improving film 2 is 10 ° or more and 20 ° or less, the first conductivity type dopant diffusing agent 3 is greatly repelled. In addition to being able to suppress the bleeding of the first conductivity type dopant diffusing agent 3, it is possible to greatly reduce the occurrence of variations in the line width of the first conductivity type dopant diffusing agent 3. It tends to be possible to apply the first conductivity type dopant diffusing agent 3 having a line width. When the contact angle θ _{1 of} the first conductivity type dopant diffusing agent 3 with respect to the first wettability improving film 2 is 10 ° or more and 20 ° or less, the first conductivity type dopant diffusing agent 3 is disconnected or The tendency that the line width of the first-conductivity-type dopant diffusing agent 3 is locally narrowed can be further effectively suppressed, and the line width of the first-conductivity-type dopant diffusing agent 3 is further effectively suppressed. The tendency to be able to increase. Therefore, from the viewpoint of stably forming the first conductivity type dopant diffusing agent 3 in a desired pattern, the contact angle θ ₁ is preferably 10 ° or more and 20 ° or less.

The contact angle θ ₁ of the first conductivity type dopant diffusing agent 3 with respect to the first wettability improving film 2 can be measured by, for example, a conventionally known contact angle meter.

  Also, when the first conductivity type is n-type, out of the line width w1 of the first conductivity type dopant diffusing agent 3 applied on the surface of the first wettability improving film 2 on the back surface of the semiconductor substrate 1 The minimum line width is preferably 100 μm or less. When the first conductivity type is n-type, and the minimum line width of the line width w1 of the first conductivity type dopant diffusing agent 3 is 100 μm or less, the first conductivity type dopant diffusing agent with a fine line width is used. 3 tends to be applied.

  Further, when the first conductivity type is p-type, of the line width w1 of the first conductivity type dopant diffusing agent 3 applied on the surface of the first wettability improving film 2 on the back surface of the semiconductor substrate 1 The minimum line width is preferably 300 μm or less. When the first conductivity type is p-type and the minimum line width of the line width w1 of the first conductivity type dopant diffusing agent 3 is 300 μm or less, the first conductivity type dopant diffusion with a fine line width is performed. It tends to be possible to apply the agent 3.

  Next, as shown in FIG. 1D, the first wettability improving film is formed from the first conductive type dopant diffusing agent 3 by heat-treating the semiconductor substrate 1 to which the first conductive type dopant diffusing agent 3 is applied. The first conductivity type dopant diffusion layer 5 is formed by diffusing the first conductivity type dopant into the semiconductor substrate 1 through 2.

  Here, the conditions for the heat treatment of the semiconductor substrate 1 are not particularly limited, but from the viewpoint of stably forming the first conductivity type dopant diffusion layer 5, the semiconductor substrate 1 is 800 ° C. or more and 1000 ° C. or less in a nitrogen atmosphere. It is preferable to heat at a temperature of 30 minutes to 60 minutes.

  Next, as shown in FIG. 1E, the first wettability improving film 2 and the first conductivity type dopant diffusing agent 3 on the back surface of the semiconductor substrate 1 are removed. As a result, the surface of the first conductivity type dopant diffusion layer 5 is exposed on the back surface of the semiconductor substrate 1.

  Here, the first wettability improving film 2 and the first conductivity type dopant diffusing agent 3 are removed by removing the first wettability improving film 2 and the first conductive type dopant diffusing agent 3 from the back surface of the semiconductor substrate 1. The method is not particularly limited as long as it can be performed.

  Next, as shown in FIG. 1F, a second wettability improving film 21 is formed on the back surface of the semiconductor substrate 1 where the first conductivity type dopant diffusion layer 5 is exposed.

  Here, the second wettability improving film 21 is used without particular limitation as long as it can stably suppress the later-described dopant diffusing agent applied on the back surface of the semiconductor substrate 1 from being repelled. be able to.

  In particular, when the semiconductor substrate 1 is a hydrophobic substrate such as a silicon substrate, it is preferable to use a hydrophilic film as the second wettability improving film 21. In this case, when a hydrophilic dopant diffusing agent is applied directly on the back surface of the hydrophobic semiconductor substrate 1, the dopant diffusing agent is stably prevented from being repelled on the back surface of the semiconductor substrate 1. This is because it can be done.

  Here, as the hydrophilic second wettability improving film 21, for example, a silicon oxide film, a silicon nitride film, a film having an OH group (hydroxyl group) on the surface, or the like is combined in a single layer or a combination of a plurality of these films. And the like can be used.

  The thickness of the second wettability improving film 21 is preferably 50 nm or less. When the thickness of the second wettability improving film 21 is 50 nm or less, the dopant tends to easily diffuse into the semiconductor substrate 1 through the second wettability improving film 21 from a dopant diffusing agent described later.

  The thickness of the second wettability improving film 21 is preferably 1 nm or more. When the thickness of the second wettability improving film 21 is 1 nm or more, the wettability improving effect due to the formation of the second wettability improving film 21 tends to be easily obtained.

  The second wettability improving film 21 can be formed by, for example, a CVD method or a thermal oxidation method.

  Next, as shown in FIG. 1G, the second conductivity type dopant diffusing agent 4 containing the second conductivity type dopant is applied on the surface of the second wettability improving film 21 on the back surface of the semiconductor substrate 1. . The 2nd conductivity type dopant diffusing agent 4 can be apply | coated to the strip | belt shape extended | stretched from the surface side of FIG.1 (g) to a back surface side, for example.

  Here, as a coating method of the second conductivity type dopant diffusing agent 4, for example, spray coating, coating using a dispenser, ink jet coating, screen printing, letterpress printing, intaglio printing, planographic printing, or the like can be used.

  In addition, as the second conductivity type dopant diffusing agent 4, one containing a second conductivity type dopant source can be used, and 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, and the second conductivity type is p-type. In this case, for example, boron oxide and boric acid, organoboron compound, boron-aluminum compound, organoaluminum compound or a compound containing boron atom and / or aluminum atom such as aluminum salt alone or in combination of two or more kinds Can be used.

  Here, as a coating method of the second conductivity type dopant diffusing agent 4, for example, spray coating, coating using a dispenser, ink jet coating, screen printing, letterpress printing, intaglio printing, planographic printing, or the like can be used.

  In addition, as the second conductivity type dopant diffusing agent 4, one containing a second conductivity type dopant source can be used, and 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, and the second conductivity type is p-type. In this case, for example, boron oxide and boric acid, organoboron compound, boron-aluminum compound, organoaluminum compound or a compound containing boron atom and / or aluminum atom such as aluminum salt alone or in combination of two or more kinds Can be used.

  Moreover, as components other than the 2nd conductivity type dopant source of the 2nd conductivity type dopant diffusing agent 4, what contains a solvent, a silane compound, and a thickener can be used, for example. In addition, as the second conductivity type dopant diffusing agent 4, those not containing a thickener can also be used. In addition, since description of components other than the 2nd conductivity type dopant source of the 2nd conductivity type dopant diffusing agent 4 is the same as that of the above, it abbreviate | omits here.

FIG. 3 is a schematic enlarged sectional view of an example of the second conductivity type dopant diffusing agent 4 applied on the surface of the second wettability improving film 21 on the back surface of the semiconductor substrate 1 shown in FIG. Show. Here, the contact angle θ ₂ of the second conductivity type dopant diffusing agent 4 with respect to the second wettability improving film 21 is preferably 5 ° or more and 30 ° or less, and more preferably 10 ° or more and 20 ° or less. .

When the contact angle θ ₂ of the second conductivity type dopant diffusing agent 4 with respect to the second wettability improving film 21 is less than 5 °, the line width of the second conductivity type dopant diffusing agent 4 is too wide, and a desired pattern is obtained. And / or the line width may not be drawn. Moreover, when said contact angle (theta) ₂ is larger than 30 degrees, while there exists a possibility that the 2nd conductivity type dopant diffusing agent 4 may be disconnected, the line edge of the 2nd conductivity type dopant diffusing agent 4 may be disturbed.

When the contact angle θ _{2 of} the second conductivity type dopant diffusing agent 4 with respect to the second wettability improving film 21 is 10 ° or more and 20 ° or less, the second conductivity type dopant diffusing agent 4 is greatly repelled. In addition to being able to suppress the bleeding of the second conductivity type dopant diffusing agent 4, it is possible to greatly reduce the occurrence of variations in the line width of the second conductivity type dopant diffusing agent 4. It tends to be possible to apply the second conductivity type dopant diffusing agent 4 having a line width. When the contact angle θ _{2 of} the second conductivity type dopant diffusing agent 4 with respect to the second wettability improving film 21 is 10 ° or more and 20 ° or less, the second conductivity type dopant diffusing agent 4 is disconnected or The tendency that the line width of the two-conductivity-type dopant diffusing agent 4 is locally narrowed can be further effectively suppressed, and the line width of the second-conductivity-type dopant diffusing agent 4 is further effectively suppressed. The tendency to be able to increase. Therefore, from the viewpoint of stably forming the second conductivity type dopant diffusing agent 4 in a desired pattern, the contact angle θ ₂ is preferably 10 ° or more and 20 ° or less.

The contact angle θ ₂ of the second conductivity type dopant diffusing agent 4 with respect to the second wettability improving film 21 can be measured by, for example, a conventionally known contact angle meter.

  When the second conductivity type is n-type, of the line width w2 of the second conductivity type dopant diffusing agent 4 applied on the surface of the second wettability improving film 21 on the back surface of the semiconductor substrate 1 The minimum line width is preferably 100 μm or less. When the second conductivity type is n-type and the minimum line width of the line width w2 of the second conductivity type dopant diffusing agent 4 is 100 μm or less, the second conductivity type dopant diffusion with a fine line width is performed. It tends to be possible to apply the agent 4.

  Further, when the second conductivity type is p-type, out of the line width w2 of the second conductivity type dopant diffusing agent 4 applied on the surface of the second wettability improving film 21 on the back surface of the semiconductor substrate 1. The minimum line width is preferably 300 μm or less. When the first conductivity type is p-type and the minimum line width among the line widths w2 of the second conductivity-type dopant diffusing agent 4 is 300 μm or less, the second conductivity-type dopant diffusion with a fine line width is performed. It tends to be possible to apply the agent 4.

  Next, as shown in FIG. 1H, the second wettability improving film is formed from the second conductive type dopant diffusing agent 4 by heat-treating the semiconductor substrate 1 to which the second conductive type dopant diffusing agent 4 is applied. The second conductivity type dopant diffusion layer 6 is formed by diffusing the second conductivity type dopant into the semiconductor substrate 1 through 21.

  Here, the conditions for the heat treatment of the semiconductor substrate 1 are not particularly limited, but from the viewpoint of stably forming the second conductivity type dopant diffusion layer 6, the semiconductor substrate 1 is 800 ° C. or more and 1000 ° C. or less in a nitrogen atmosphere. It is preferable to heat at a temperature of 30 minutes to 60 minutes.

  Next, as shown in FIG. 1I, the second wettability improving film 21 and the second conductivity type dopant diffusing agent 4 on the back surface of the semiconductor substrate 1 are removed. As a result, the surface of the first conductivity type dopant diffusion layer 5 and the surface of the second conductivity type dopant diffusion layer 6 are exposed at a predetermined interval on the back surface of the semiconductor substrate 1.

  Here, the second wettability improving film 21 and the second conductivity type dopant diffusing agent 4 are removed by removing the second wettability improving film 21 and the second conductivity type dopant diffusing agent 4 from the back surface of the semiconductor substrate 1. The method is not particularly limited as long as it can be performed.

  Next, as shown in FIG. 1 (j), a passivation film 7 is formed on the back surface of the semiconductor substrate 1 where the first conductivity type dopant diffusion layer 5 and the second conductivity type dopant diffusion layer 6 are exposed. An antireflection film 9 is formed on the surface of the semiconductor substrate 1 on which the texture structure 8 is formed.

  Here, as the passivation film 7, for example, a silicon oxide film, a silicon nitride film, or a stacked body of a silicon oxide film and a silicon nitride film can be used. Further, the passivation film 7 can be formed by, for example, a plasma CVD method.

  In addition, as the antireflection film 9, for example, a silicon oxide film, a silicon nitride film, or a stacked body of a silicon oxide film and a silicon nitride film can be used. The antireflection film 9 can be formed by, for example, a plasma CVD method.

  Next, as shown in FIG. 1 (k), a part of the passivation film 7 of the semiconductor substrate 1 is removed to form a contact hole 12 and a contact hole 13, and the first conductivity type dopant diffusion is performed from the contact hole 12. The surface of the layer 5 is exposed and the surface of the second conductivity type dopant diffusion layer 6 is exposed from the contact hole 13.

  Here, for the contact hole 12 and the contact hole 13, for example, a resist pattern having an opening at a portion corresponding to each formation position of the contact hole 12 and the contact hole 13 is formed on the passivation film 7 by using a photolithography technique. A method of removing the passivation film 7 from the opening of the resist pattern later by etching or the like, or by applying an etching paste to the portion of the passivation film 7 corresponding to each formation position of the contact hole 12 and the contact hole 13 and then heating the passivation film 7 The film 7 can be formed by etching or the like.

  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 of ethylene glycol, ethylene glycol monobutyl ether, propylene carbonate, N-methyl-2-pyrrolidone and the like can be used. Moreover, as a thickener, at least 1 sort (s), such as a cellulose, ethylcellulose, a cellulose derivative, nylon 6, or polyvinylpyrrolidone, can be used, for example.

  Next, as shown in FIG. 1 (l), the first conductivity type electrode 10 electrically connected to the first conductivity type dopant diffusion layer 5 through the contact hole 12 is formed, and the second through the contact hole 13 is formed. A second conductivity type electrode 11 electrically connected to the conductivity type dopant diffusion layer 6 is formed.

  Here, as the first conductivity type electrode 10 and the second conductivity type electrode 11, 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. 4, the typical top view of an example of the back surface of the back electrode type solar cell produced by the manufacturing method of the solar cell of this invention is shown.

  Here, as shown in FIG. 4, on the back surface of the back electrode type solar cell, a plurality of strip-shaped first conductivity type electrodes 10 and a plurality of strip-shaped second conductivity type electrodes 11 are alternately arranged one by one. All the first conductivity type electrodes 10 are arranged at intervals, and all the first conductivity type electrodes 10 are electrically connected to one strip-shaped first conductivity type current collecting electrode 10a. 11 is electrically connected to one strip-shaped second-conductivity-type collecting electrode 11a.

  In addition, on the back surface of the back electrode type solar cell, a high-concentration first conductivity type dopant diffusion layer 5 is disposed below each of the plurality of strip-shaped first conductivity type electrodes 10 to form a plurality of strip-shaped second conductivity types. The second conductivity type dopant diffusion layer 6 is disposed below each of the electrodes 11 for use. The shape and size of the first conductivity type dopant diffusion layer 5 and the second conductivity type dopant diffusion layer 6 are as follows. There is no particular limitation. For example, the first conductivity type dopant diffusion layer 5 and the second conductivity type dopant diffusion layer 6 may be formed in a strip shape along each of the first conductivity type electrode 10 and the second conductivity type electrode 11, The first conductivity type electrode 10 and the second conductivity type electrode 11 may be formed in a dot shape in contact with each part.

  In FIG. 5, the typical top view of another example of the back surface of the back electrode type solar cell produced by the manufacturing method of the solar cell of this invention is shown. Here, as shown in FIG. 5, the first conductivity type electrode 10 and the second conductivity type electrode 11 are each formed in a strip shape extending in the same direction (extending in the vertical direction in FIG. 5). One of them is alternately arranged in the direction perpendicular to the extension direction on the back surface of one.

  FIG. 6 shows a schematic plan view of still another example of the back surface of a back electrode type solar cell manufactured by the method for manufacturing a solar cell of the present invention. Here, as shown in FIG. 6, the first conductivity type electrode 10 and the second conductivity type electrode 11 are each formed in a dot shape, and the row of the first conductivity type electrodes 10 in a dotted shape (FIG. 6). Of the second conductive type electrodes 11 (extending in the vertical direction or the horizontal direction in FIG. 6) are alternately arranged one by one on the back surface of the semiconductor substrate 1. Yes.

  In FIG. 1A to FIG. 1L, for convenience of explanation, only one first conductivity type dopant diffusion layer 5 and one second conductivity type dopant diffusion layer 6 are formed on the semiconductor substrate 1. It is needless to say that a plurality of first conductivity type dopant diffusion layers 5 and a plurality of second conductivity type dopant diffusion layers 6 may actually be formed.

  In the above, the first conductivity type may be either n-type or p-type, and the second conductivity type may be any conductivity type opposite to the first conductivity type. That is, when the first conductivity type is n-type, the second conductivity type is p-type, and when the first conductivity type is p-type, the second conductivity type is n-type.

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

  In addition, when the second conductivity type is n-type, for example, an n-type dopant such as phosphorus can be used as the second conductivity type dopant, and when the second conductivity type is p-type, As the two-conductivity type dopant, for example, a p-type dopant such as boron or aluminum can be used.

  As exemplified above, in the present invention, the dopant diffusing agent is applied after the wettability improving film is formed on the surface of the semiconductor substrate. Even when a dopant diffusing agent having a property of being repelled on the surface is used, the repelling of the dopant diffusing agent can be stably suppressed.

  Therefore, in the present invention, even when a dopant diffusing agent is applied to form a dopant diffusing layer, the occurrence of fragmentation of the dopant diffusing agent on the surface of the semiconductor substrate is avoided, for example, as shown in FIG. Since the tendency to be able to be increased, the dopant diffusion layer can be stably formed at a desired position, so that the deterioration of the characteristics of the solar cell can be stably suppressed.

<Embodiment 2>
In the present embodiment, after applying both the first conductivity type dopant diffusing agent 3 and the second conductivity type dopant diffusing agent 4 on the first wettability improving film 2 formed on the back surface of the semiconductor substrate 1. The semiconductor substrate 1 is characterized in that the first conductivity type dopant diffusion layer 5 and the second conductivity type dopant diffusion layer 6 are simultaneously formed by heat treatment.

  Hereinafter, a method for manufacturing a solar cell in the present embodiment will be described with reference to schematic cross-sectional views of FIGS. 7 (a) to 7 (h). 7A to 7H, only one first conductivity type dopant diffusion layer 5 and one second conductivity type dopant diffusion layer 6 are formed on the semiconductor substrate 1 for convenience of explanation. It is needless to say that a plurality of first conductivity type dopant diffusion layers 5 and a plurality of second conductivity type dopant diffusion layers 6 may actually be formed.

  First, as shown in FIG. 7A, a semiconductor substrate 1 on which a texture structure 8 made of, for example, pyramidal irregularities is formed is prepared. Subsequently, as shown in FIG. 7B, the semiconductor substrate 1 is prepared. The first wettability improving film 2 is formed on the back surface, which is the surface opposite to the surface on which the texture structure 8 is formed.

  Next, as shown in FIG. 7C, the first conductivity type dopant diffusing agent 3 containing the first conductivity type dopant on the first wettability improving film 2 formed on the back surface of the semiconductor substrate 1 and the first The 2nd conductivity type dopant diffusing agent 4 containing a 2 conductivity type dopant is each apply | coated.

  In addition, application | coating of the 1st conductivity type dopant diffusing agent 3 and the 2nd conductivity type dopant diffusing agent 4 in this Embodiment is the 1st conductivity type dopant diffusing agent 3 and the 2nd conductivity type dopant diffusion in Embodiment 1, for example. It can apply | coat by the method similar to the agent 4.

  Next, as shown in FIG. 7 (d), the semiconductor substrate 1 is heat-treated, so that the first conductivity type dopant is transferred from the first conductivity type dopant diffusing agent 3 and the second conductivity type dopant diffusing agent 4 to the semiconductor substrate 1, respectively. The first conductivity type dopant diffusion layer 5 and the second conductivity type dopant diffusion layer 6 are formed by diffusing the second conductivity type dopant.

  Here, the first conductive dopant is diffused by diffusing the first conductive dopant from the first conductive dopant diffusing agent 3 to the semiconductor substrate 1 through the first wettability improving film 2 by the heat treatment of the semiconductor substrate 1 described above. The layer 5 is formed, and the second conductivity type dopant diffusion layer 6 is formed by diffusing the second conductivity type dopant from the second conductivity type dopant diffusing agent 4 to the semiconductor substrate 1 through the first wettability improving film 2. .

  Here, the conditions for the heat treatment of the semiconductor substrate 1 are not particularly limited. From the viewpoint of stably forming the first conductivity type dopant diffusion layer 5 and the second conductivity type dopant diffusion layer 6, the semiconductor substrate 1 is It is preferable to heat at a temperature of 800 ° C. to 1000 ° C. for 30 minutes to 60 minutes in a nitrogen atmosphere.

  Next, as shown in FIG. 7E, the first wettability improving film 2, the first conductivity type dopant diffusing agent 3 and the second conductivity type dopant diffusing agent 4 on the back surface of the semiconductor substrate 1 are removed. Thus, the surfaces of the first conductivity type dopant diffusion layer 5 and the second conductivity type dopant diffusion layer 6 are respectively exposed on the back surface of the semiconductor substrate 1.

  Next, as shown in FIG. 7 (f), a passivation film 7 is formed on the back surface of the semiconductor substrate 1 where the first conductivity type dopant diffusion layer 5 and the second conductivity type dopant diffusion layer 6 are respectively exposed. An antireflection film 9 is formed on the surface of the semiconductor substrate 1 on which the texture structure 8 is formed.

  Next, as shown in FIG. 7G, a part of the passivation film 7 of the semiconductor substrate 1 is removed to form a contact hole 12 and a contact hole 13, and the first conductivity type dopant diffusion is performed from the contact hole 12. The surface of the layer 5 is exposed and the surface of the second conductivity type dopant diffusion layer 6 is exposed from the contact hole 13.

  Next, as shown in FIG. 7 (h), the first conductivity type electrode 10 electrically connected to the first conductivity type dopant diffusion layer 5 through the contact hole 12 is formed, and the second through the contact hole 13. A second conductivity type electrode 11 electrically connected to the conductivity type dopant diffusion layer 6 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.

  As in the method for manufacturing a solar cell in the present embodiment, the first conductivity type dopant diffusing agent 3 and the second conductivity type dopant diffusing agent are formed on the first wettability improving film 2 formed on the surface of the semiconductor substrate 1. When both the first conductive type dopant diffusion layer 5 and the second conductive type dopant diffusion layer 6 are simultaneously formed by heat-treating the semiconductor substrate 1 after coating both of the first conductive type dopant diffusion layer 5 and the second conductive type 4 Since the heat treatment for forming the two-conductivity-type dopant diffusion layer 6 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. .

  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 first conductivity type dopant diffusing agent 3 is applied on the third wettability improving film 31 formed on the back surface of the semiconductor substrate 1 and then the semiconductor substrate 1 is heat-treated to thereby perform the first treatment. The high-concentration first conductivity type dopant diffusion layer 15 is formed by solid phase diffusion of the first conductivity type dopant from the conductivity type dopant diffusing agent 3 and the first conductivity type dopant from the first conductivity type dopant diffusing agent 3 is formed. The low-concentration first conductivity type dopant diffusion layer 16 is formed by diffusion by out-diffusion.

  Hereinafter, a method for manufacturing the solar cell in the present embodiment will be described with reference to schematic cross-sectional views of FIGS. 8A to 8L, only one high-concentration first-conductivity-type dopant diffusion layer 15 and one second-conductivity-type dopant diffusion layer 6 are provided on the semiconductor substrate 1 for convenience of explanation. Although shown as being formed, it goes without saying that a plurality of high-concentration first conductivity type dopant diffusion layers 15 and a plurality of second conductivity type dopant diffusion layers 6 may actually be formed.

  First, as shown in FIG. 8A, a semiconductor substrate 1 on which a texture structure 8 made of, for example, pyramidal irregularities is formed is prepared. Subsequently, as shown in FIG. A third wettability improving film 31 is formed on the back surface that is the surface opposite to the surface on which the texture structure 8 is formed.

  Here, as the third wettability improving film 31, it is possible to stably suppress the first conductivity type dopant diffusing agent 3 applied on the surface of the semiconductor substrate 1 from being repelled and to perform the first conductivity. In addition to the formation of the high-concentration first-conductivity-type dopant diffusion layer 15 by solid-phase diffusion of the first-conductivity-type dopant from the first-conductivity-type dopant diffusing agent 3, There is no particular limitation as long as the low-concentration first conductivity type dopant diffusion layer 16 can be formed by diffusion.

  The solid phase diffusion of the first conductivity type dopant from the first conductivity type dopant diffusing agent 3 is such that the first conductivity type dopant directly passes through the third wettability improving film 31 from the first conductivity type dopant diffusing agent 3. This is performed by diffusing into the semiconductor substrate 1.

  In addition, the diffusion of the first conductivity type dopant from the first conductivity type dopant diffusing agent 3 by out diffusion diffuses the first conductivity type dopant from the first conductivity type dopant diffusing agent 3 once into the gas phase surrounding the semiconductor substrate 1. Thereafter, the first conductivity type dopant diffused in the gas phase is diffused into the semiconductor substrate 1 through the third wettability improving film 31.

  When the semiconductor substrate 1 is a hydrophobic substrate such as a silicon substrate, it is preferable to use a hydrophilic film as the third wettability improving film 31. In this case, when a hydrophilic dopant diffusing agent is applied directly on the surface of the hydrophobic semiconductor substrate 1, the dopant diffusing agent is stably prevented from being repelled on the surface of the semiconductor substrate 1. This is because it can be done.

  Here, as the hydrophilic third wettability improving film 31, for example, a silicon oxide film, a silicon nitride film, a film having an OH group (hydroxyl group) on the surface, or the like is combined in a single layer or a combination of a plurality of these films. And the like can be used.

  The third wettability improving film 31 can be formed by, for example, a CVD method or a thermal oxidation method.

  Next, as shown in FIG. 8C, the first conductivity type dopant diffusing agent 3 containing the first conductivity type dopant is applied on the third wettability improving film 31 on the surface of the semiconductor substrate 1.

  Next, as shown in FIG. 8D, by heat-treating the semiconductor substrate 1, the first conductivity type dopant is passed from the first conductivity type dopant diffusing agent 3 through the third wettability improving film 31 by solid phase diffusion. A high-concentration first conductivity type dopant diffusion layer 15 is formed by diffusing into the semiconductor substrate 1 and the first conductivity type dopant is diffused from the first conductivity type dopant diffusing agent 3 by outdiffusion to form a third wettability improving film 31. The low-concentration first-conductivity-type dopant diffusion layer 16 is formed by diffusing through the semiconductor substrate 1.

  Here, the conditions for the heat treatment of the semiconductor substrate 1 are not particularly limited. From the viewpoint of stably forming the high concentration first conductivity type dopant diffusion layer 15 and the low concentration first conductivity type dopant diffusion layer 16, the semiconductor It is preferable to heat the substrate 1 at a temperature of 800 ° C. to 1000 ° C. for 30 minutes to 60 minutes in a nitrogen atmosphere.

  Next, as shown in FIG. 8E, by removing the third wettability improving film 31 and the first conductivity type dopant diffusing agent 3 on the surface of the semiconductor substrate 1, The surfaces of the high concentration first conductivity type dopant diffusion layer 15 and the low concentration first conductivity type dopant diffusion layer 16 are exposed.

  Next, as shown in FIG. 8F, the second wettability is formed on the back surface of the semiconductor substrate 1 where the high concentration first conductivity type dopant diffusion layer 15 and the low concentration first conductivity type dopant diffusion layer 16 are exposed. An improvement film 21 is formed.

  Next, as shown in FIG. 8G, the second conductivity type dopant diffusing agent 4 containing the second conductivity type dopant is applied on the surface of the second wettability improving film 21 on the back surface of the semiconductor substrate 1. Later, the semiconductor substrate 1 is heat-treated. As a result, as shown in FIG. 8H, the second conductivity type dopant is solid-phase diffused from the second conductivity type dopant diffusing agent 4 through the second wettability improving film 21 to the semiconductor substrate 1 to obtain the second conductivity type. A dopant diffusion layer 6 is formed.

  Next, as shown in FIG. 8I, the second wettability improving film 21 and the second conductivity type dopant diffusing agent 4 on the back surface of the semiconductor substrate 1 are removed. As a result, the surfaces of the high concentration first conductivity type dopant diffusion layer 15, the low concentration first conductivity type dopant diffusion layer 16 and the second conductivity type dopant diffusion layer 6 are exposed on the back surface of the semiconductor substrate 1.

  Next, as shown in FIG. 8J, the surfaces of the high concentration first conductivity type dopant diffusion layer 15, the low concentration first conductivity type dopant diffusion layer 16 and the second conductivity type dopant diffusion layer 6 of the semiconductor substrate 1 are A passivation film 7 is formed on each exposed back surface, and an antireflection film 9 is formed on the surface of the semiconductor substrate 1 on which the texture structure 8 is formed.

  Next, as shown in FIG. 8 (k), a part of the passivation film 7 of the semiconductor substrate 1 is removed to form a contact hole 12 and a contact hole 13, and the high-concentration first conductivity type is formed from the contact hole 12. The surface of the dopant diffusion layer 15 is exposed and the surface of the second conductivity type dopant diffusion layer 6 is exposed from the contact hole 13.

  Next, as shown in FIG. 8L, the first conductivity type electrode 10 electrically connected to the high-concentration first conductivity type dopant diffusion layer 15 through the contact hole 12 is formed, and through the contact hole 13. A second conductivity type electrode 11 electrically connected to the second conductivity type dopant diffusion layer 6 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.

  As in the solar cell manufacturing method of the present embodiment, the first conductivity type dopant diffusion layer formed on the semiconductor substrate 1 is divided into the high concentration first conductivity type dopant diffusion layer 15 and the low concentration first conductivity type dopant diffusion layer 16. When it is formed separately, the characteristics of the back electrode type solar cell tend to be further improved.

The high concentration first conductivity type dopant diffusion layer 15 is a layer having a first conductivity type dopant concentration higher than that of the low concentration first conductivity type dopant diffusion layer 16. Here, the 1st conductivity type dopant density | concentration in the high concentration 1st conductivity type dopant diffusion layer 15 can be 1 * 10 < ¹⁹ > / cm < ³ > or more, for example. The first conductivity type dopant concentration in the low concentration first conductivity type dopant diffusion layer 16 may be, for example, less than 1 × 10 ¹⁷ / cm ³ to 1 × 10 ¹⁹ / cm ^3.

  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 4>
The present embodiment is characterized in that a double-sided electrode type solar cell provided with electrodes on the light receiving surface and the back side of a semiconductor substrate, not a back electrode type solar cell, is produced.

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

  First, as shown in FIG. 9A, a semiconductor substrate 1 made of a p-type silicon substrate is prepared, and subsequently, a silicon oxide film is formed on one surface of the semiconductor substrate 1 as shown in FIG. 9B. A third wettability improving film 31 is formed.

  Next, as shown in FIG. 9C, n containing phosphorus as an n-type dopant is formed on the third wettability improving film 31 made of a silicon oxide film on the surface of the semiconductor substrate 1 made of a p-type silicon substrate. A type dopant diffusing agent is applied as the first conductivity type dopant diffusing agent 3.

  Next, as shown in FIG. 9D, the semiconductor substrate 1 made of a p-type silicon substrate is heat-treated to pass through the third wettability improving film 31 from the first conductivity type dopant diffusing agent 3 containing phosphorus. Phosphorus is solid-phase diffused on the surface of the semiconductor substrate 1 to form a high-concentration n-type dopant diffusion layer as the high-concentration first conductivity-type dopant diffusion layer 15, and third wetting from the first conductivity-type dopant diffusing agent 3 A low-concentration n-type dopant diffusion layer as the low-concentration first conductivity type dopant diffusion layer 16 is formed by diffusing phosphorus by diffusion by out-diffusion on the surface of the semiconductor substrate 1 through the property improving film 31.

  Note that preferable conditions and the like for the heat treatment of the semiconductor substrate 1 are the same as those in the first and second embodiments, and a description thereof will be omitted.

  Next, as shown in FIG. 9 (e), by removing the first conductivity type dopant diffusing agent 3 and the third wettability improving film 31 from the surface of the semiconductor substrate 1, The surfaces of the high-concentration n-type dopant diffusion layer as the concentration first conductivity-type dopant diffusion layer 15 and the low-concentration n-type dopant diffusion layer as the low-concentration first conductivity-type dopant diffusion layer 16 are exposed, respectively. A silver electrode as the first conductivity type electrode 10 is formed on the surface of the high-concentration n-type dopant diffusion layer as the type dopant diffusion layer 15.

  Next, as shown in FIG. 9 (f), a silver electrode as the second conductivity type electrode 11 is formed on the back surface opposite to the front surface serving as the light receiving surface of the semiconductor substrate 1.

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

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

  The concept of the solar cell of the present invention includes only the back electrode type solar cell having a configuration in which both the first conductivity type electrode and the second conductivity type electrode are formed only on one surface (back surface) of the semiconductor substrate. Rather, so-called back contact solar cells (on the side opposite to the light receiving surface of the solar cells) such as MWT (Metal Wrap Through) cells (solar cells having a configuration in which a part of an electrode is disposed in a through hole provided in a semiconductor substrate) Solar cells having a structure in which current is taken out from the back surface) and double-sided electrode type solar cells manufactured by forming electrodes on the light receiving surface and the back surface of the semiconductor substrate are included.

  First, a hydrophobic n-type silicon substrate was prepared by removing a slice damage layer of an n-type silicon wafer having a square surface with a side of 100 mm and a thickness of about 200 μm with a sodium hydroxide solution.

  Next, a hydrophilic silicon oxide film having a thickness of 25 nm was formed as a wettability improving film on one surface of the n-type silicon substrate by a thermal CVD method.

Thereafter, the viscosity of the p-type dopant diffusing agent obtained by mixing boron oxide (B ₂ O ₃ ), a predetermined silane compound, propylene glycol monomethyl ether, water, and acetic anhydride is variously changed to thereby have a plurality of hydrophilic properties different in viscosity. P-type dopant diffusing agent was prepared.

Further, a plurality of hydrophilic substances having different viscosities can be obtained by varying the viscosity of the n-type dopant diffusing agent obtained by mixing diphosphorus pentoxide (P ₂ O ₅ ), a predetermined silane compound, ethylene glycol, and acetic anhydride. An n-type dopant diffusing agent was prepared.

  Then, the p-type dopant diffusing agent and the n-type dopant diffusing agent produced as described above were each applied linearly on the surface of the wettability improving film by an ink jet coating method. Here, the p-type dopant diffusing agent is applied linearly so that the minimum line width is 300 μm or less, and the n-type dopant diffusing agent is applied linearly so that the minimum line width is 100 μm or less. did.

  And while observing whether or not the fragmentation due to the p-type dopant diffusing agent and the n-type dopant diffusing agent being repelled occurs during the application of the p-type dopant diffusing agent and the n-type dopant diffusing agent, respectively, The contact angle of each of the p-type dopant diffusing agent and the n-type dopant diffusing agent after application to the wettability improving film was measured with a conventionally known contact angle meter.

  As a comparison, the p-type dopant diffusing agent and the n-type dopant diffusing agent prepared as described above were each applied directly and linearly on the surface of the n-type silicon substrate by the inkjet coating method, and the p-type dopant diffusing was performed. It was visually observed whether or not the fragmentation due to the repelling of the agent and the n-type dopant diffusing agent occurred. Again, the p-type dopant diffusing agent was applied linearly so that the minimum line width was 300 μm or less, and the n-type dopant diffusing agent was applied linearly so that the minimum line width was 100 μm or less. .

  As a result, when the p-type dopant diffusing agent and the n-type dopant diffusing agent are applied after forming the wettability improving film on the surface of the n-type silicon substrate, the wettability improving film is formed on the surface of the n-type silicon substrate. Compared with the case where the p-type dopant diffusing agent and the n-type dopant diffusing agent were applied without forming the p-type dopant diffusing agent and the n-type dopant diffusing agent, the number of occurrences of each division was greatly reduced.

  In the case where the contact angle with respect to the wettability improving film of the p-type dopant diffusing agent having a viscosity at room temperature (25 ° C.) in a predetermined range (5 Pa · s to 25 Pa · s) is 10 ° or more and 20 ° or less. It has been confirmed that the number of occurrences of the p-type dopant diffusing agent is further greatly reduced.

  In the case where the contact angle of the n-type dopant diffusing agent having a viscosity at room temperature (25 ° C.) in a predetermined range (5 Pa · s to 25 Pa · s) with respect to the wettability improving film is 10 ° or more and 20 ° or less. It has been confirmed that the number of occurrences of the n-type dopant diffusing agent is further greatly reduced.

  Then, after forming a wettability improving film on the surface of the n-type silicon substrate as described above, a p-type dopant diffusing agent and an n-type dopant diffusing agent are applied, and then the n-type silicon substrate is heat-treated to form p on the back surface. When the back electrode type solar cell was produced using the n-type silicon substrate in which the n-type dopant diffusion layer and the n-type dopant diffusion layer were formed and the characteristics thereof were evaluated, it was confirmed that excellent characteristics were exhibited.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. 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.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the semiconductor device which can suppress the fall of the characteristic of a semiconductor device stably can be provided.

  In particular, the method for manufacturing a semiconductor device of the present invention can be suitably used as a method for manufacturing a solar cell.

  DESCRIPTION OF SYMBOLS 1 Semiconductor substrate, 2 1st wettability improvement film | membrane, 3 1st conductivity type dopant diffuser, 4 2nd conductivity type dopant diffuser, 5 1st conductivity type dopant diffusion layer, 6 2nd conductivity type dopant diffusion layer, 7 Passivation film, 8,108 texture structure, 9 antireflection film, 10 first conductivity type electrode, 10a first conductivity type current collecting electrode, 11 second conductivity type electrode, 11a second conductivity type current collecting electrode, 12, 13 contact hole, 15 high concentration first conductivity type dopant diffusion layer, 16 low concentration first conductivity type dopant diffusion layer, 21 second wettability improvement film, 31 third wettability improvement film, 100 silicon substrate, 102 oxide layer, 103 p-type doping paste, 104 n-type doping paste, 105 p-type dopant diffusion layer, 106 n-type dopant diffusion layer, 110, 11 Metallization.

Claims (5)

Forming a wettability improving film on the surface of the semiconductor substrate;
Applying a dopant diffusing agent containing a first conductivity type or second conductivity type dopant on the surface of the wettability improving film;
Forming a dopant diffusion layer by diffusing the dopant from the dopant diffusing agent into the semiconductor substrate.   2. The method of manufacturing a semiconductor device according to claim 1, wherein a contact angle of the dopant diffusing agent after the application is 5 ° or more and 30 ° or less.   3. The method of manufacturing a semiconductor device according to claim 1, wherein in the step of forming the wettability improving film, the wettability improving film is formed to a thickness of 50 nm or less.   The method for manufacturing a semiconductor device according to claim 1, wherein the wettability improving film is hydrophilic.   5. The method of manufacturing a semiconductor device according to claim 1, wherein in the step of applying the dopant diffusing agent, the dopant diffusing agent is applied so that a minimum line width is 300 μm or less. Method.

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