JP2010157655A - Method of manufacturing solar cell element, and compound semiconductor wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an electrode material of a light reception surface from being etched in etching a contact layer, and to keep high photoelectric conversion efficiency. <P>SOLUTION: This method of manufacturing a solar cell element including a compound semiconductor wafer with a solar cell layer and a contact layer sequentially formed on a substrate includes processes of: forming a protective film on the contact layer; applying photoresist on the protective film and thereafter forming an electrode pattern by photolithography; removing the protective film by etching by using the photoresist as a mask; laminating an electrode material on the contact layer by vapor deposition, and thereafter forming a laminated electrode by lift-off; forming a coating film by a material insoluble in an etchant for removing the contact layer on a surface of the laminated electrode by using the protective film as a mask and forming a light reception surface electrode; removing the protective film; and removing the contact layer by etching by using the light reception surface electrode as a mask. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a solar cell element and a compound semiconductor wafer for a solar cell element.

  2. Description of the Related Art Conventionally, as a method for manufacturing a compound semiconductor solar cell element, a method of forming a light-receiving surface electrode using relatively inexpensive Ag instead of expensive Au is known. First, a solar cell layer that is a compound semiconductor layer including a pn junction is formed on a substrate by MOCVD or the like. A compound semiconductor for electrically connecting the solar cell layer and the light receiving surface electrode on the solar cell layer and preventing the light receiving surface electrode from diffusing into the solar cell layer and degrading the characteristics of the solar cell A contact layer is formed.

  Subsequently, a resist is applied to the surface of the contact layer, a light-receiving surface electrode pattern is formed by photolithography, and a metal film made of AuGe, Ni, and Au that forms part of the light-receiving surface electrode is formed thereon by vacuum deposition. . Thereafter, an AuGe / Ni / Au laminated electrode having a desired pattern is formed by lift-off.

  Then, using the AuGe / Ni / Au laminated electrode as a mask, the contact layer where the AuGe / Ni / Au laminated electrode is not formed is removed by etching. A mixed aqueous solution of ammonia water and hydrogen peroxide water is used as an etching solution.

  Next, a resist pattern is formed by photolithography so that a window is opened only in the AuGe / Ni / Au laminated electrode portion, and an Ag film is formed thereon by vacuum deposition. Thereafter, a light receiving surface electrode having a desired pattern is formed by lift-off. Thereafter, the light-receiving surface electrode is sintered at 300 ° C. to 450 ° C. in an inert gas atmosphere such as nitrogen.

  Next, a mesa etching pattern is formed on the surface of the solar cell layer by photolithography, and the solar cell layer in the mesa-etched portion is removed by etching to expose the substrate. Etching is performed using a hydrochloric acid aqueous solution and a mixed aqueous solution of ammonia and hydrogen peroxide. Subsequently, the mesa etching pattern is diced and cut into a desired cell shape.

Next, a back electrode made of Au and Ag is formed on the back surface of the substrate by vacuum deposition. Next, a TiO ₂ film and an Al ₂ O ₃ film are formed as an antireflection film on the surface of the solar cell layer by vacuum deposition.

  Finally, sintering of the back electrode and the antireflection film is performed in the same procedure as described above to obtain a compound semiconductor solar cell element.

  FIG. 5 shows an example of a compound semiconductor solar cell element obtained by a conventional manufacturing method. FIG. 5A is a schematic sectional view thereof, and FIG. 5B is a sectional view of an electrode portion. A solar cell layer 502 which is a compound semiconductor layer including a pn junction is provided on a substrate 501, and a contact layer 503 and a light receiving surface electrode 504 are formed thereon. Further, an antireflection film 507 is formed in a portion where the contact layer 503 and the light receiving surface electrode 504 are not formed. A back electrode 506 is formed under the substrate 501.

As shown in FIG. 5B, the structure of the light-receiving surface electrode 504 includes an AuGe layer 504d, a Ni layer 504c, an Au layer 504b, and an Ag layer 504a that occupies most of the light-receiving surface electrode 504 from the lower layer. In actual manufacturing, it is difficult to align the AuGe / Ni / Au laminated electrode pattern and the Ag electrode layer pattern. Therefore, the AuGe / Ni / Au laminated electrode pattern is widened and aligned with respect to the Ag electrode layer pattern. The margin for the error is secured. That is, the AuGe layer 504d, the Ni layer 504c, the Au layer 504b, and the contact layer 503 are wider than the Ag layer 504a that occupies most of the light-receiving surface electrode 504. For this reason, the area of the electrode part in the light-receiving surface of a solar cell becomes large, a light-receiving area reduces, and photoelectric conversion efficiency falls.
In order to solve this problem, in Patent Document 1, an AuGe / Ni / Au / Ag multilayer electrode having a desired pattern is formed on a contact layer by lift-off, and then an AuGe / Ni / Au / Ag multilayer electrode is formed by plating. Cover with Au, which is a material insoluble in the etching solution for removing the contact layer, and etch the contact layer using the coated light-receiving surface electrode as a mask to reduce costs and prevent reduction in photoelectric conversion efficiency. I am trying.

JP 2004-186499 A

  However, in actual manufacturing, it is difficult to stably form an inversely tapered resist pattern, and in a general vapor deposition apparatus, the positional relationship between the vapor deposition source and the vapor deposition target and the holder on which the vapor deposition target is mounted. For reasons such as rotating, the deposition material is deposited in an oblique direction rather than a vertical direction with respect to the deposition object. That is, the resist side surface and the AuGe / Ni / Au / Ag multilayer electrode side surface are in contact with each other, and the side surface of the AuGe / Ni / Au / Ag multilayer electrode is made of a material insoluble in an etching solution for removing the contact layer by plating. It cannot be coated. Therefore, when the contact layer is etched, Ag occupying most of the light receiving surface electrode is etched, and the photoelectric conversion efficiency is lowered.

The present invention includes a compound semiconductor wafer in which a solar cell layer and a contact layer are sequentially formed on a substrate.
(1) forming a protective film on the contact layer;
(2) forming an electrode pattern by photolithography after applying a photoresist on the protective film;
(3) removing the protective film by etching using the photoresist as a mask;
(4) forming a laminated electrode by lift-off after laminating an electrode material on the contact layer by vapor deposition;
(5) forming a light-receiving surface electrode by forming a coating film with a material insoluble in an etching solution for removing a contact layer on the surface of the laminated electrode using the protective film as a mask;
(6) removing the protective film;
Removing the contact layer by etching using the light-receiving surface electrode as a mask;
It is a manufacturing method of the solar cell element characterized by including.

  The material insoluble in the etching solution for removing the contact layer is preferably a conductor made of Au, Pt, Ni, Ti, or an alloy thereof. The protective film preferably has an insulating property.

  In the present invention, the coating film made of a material insoluble in an etching solution for removing the contact layer can be formed by plating. Further, the coating film of the material insoluble in the etching solution for removing the contact layer is a method of exposing the protective film by etching or polishing after forming the material so as to cover the entire surface of the solar cell element Can be formed.

  According to the present invention, in a solar cell element including a compound semiconductor wafer in which a solar cell layer and a contact layer are sequentially formed on a substrate, a compound semiconductor layer insoluble in an etching solution for removing the contact layer is formed on the contact layer. The present invention relates to a compound semiconductor wafer for a solar cell element.

A method for manufacturing a solar cell element in another embodiment of the present invention is as follows.
(1) forming an electrode pattern by photolithography after applying a photoresist on the compound semiconductor wafer for the solar cell element;
(2) etching the compound semiconductor layer using the photoresist as a mask;
(3) forming a laminated electrode by lift-off after laminating electrode materials by vapor deposition;
(4) forming a light-receiving surface electrode by coating the surface of the stacked electrode with the compound semiconductor layer as a mask and coating a material insoluble in an etching solution for removing the contact layer;
(5) removing the compound semiconductor layer;
(6) A method of manufacturing a solar cell element including a step of removing a contact layer by etching using the light-receiving surface electrode as a mask.

  Here, the material insoluble in the etching solution for removing the contact layer is preferably a conductor made of Au, Pt, Ni, Ti, or an alloy thereof. The compound semiconductor layer preferably has an insulating property.

  Furthermore, a coating film made of a material insoluble in an etching solution for removing the contact layer can be formed by plating. In addition, a coating film of a material insoluble in an etching solution for removing the contact layer is formed by covering the entire surface of the solar cell element, and then exposing the surface of the compound semiconductor layer by etching or polishing. It can form by the method of making it.

  In the present invention, the step of forming a contact layer pattern, for example, an AuGe / Ni / Au electrode pattern, can be omitted, and further, for example, the work of aligning the Ag electrode pattern on the AuGe / Ni / Au electrode can be omitted. Furthermore, even if it is the resistance of the same light receiving surface electrode, the area of a light receiving surface electrode can be made small and a photoelectric conversion efficiency can be improved. Moreover, a sufficient space can be secured around the laminated electrode (mainly Ag electrode), a coating film can be reliably formed on the surface of the laminated electrode, and the laminated electrode is etched due to insufficient coating. And the photoelectric conversion efficiency can be kept high.

It is sectional drawing of the solar cell element in each process of the manufacturing method of the solar cell element in Embodiment 1 of this invention. It is sectional drawing of the solar cell element in each process of the manufacturing method of the solar cell element in Embodiment 2 of this invention. It is sectional drawing which shows the compound semiconductor wafer in Embodiment 3 of this invention. It is sectional drawing of the solar cell element in each process of the manufacturing method of the solar cell element in Embodiment 4 of this invention. It is sectional drawing which shows the conventional solar cell element.

<Embodiment 1>
FIG. 1 is a diagram showing each step of a method for producing a compound semiconductor solar cell element according to Embodiment 1 of the present invention.

  FIG. 1A shows the compound semiconductor wafer 105 after the InGaP solar cell layer 102 and the GaAs contact layer 103 are sequentially formed on the Ge substrate 101. Here, a material such as Ge, GaP, GaAs, or InP can be used for the substrate 101. The structure of the solar cell layer includes a base layer, an emitter layer, and a window layer. In addition to these base layers, a buffer layer and a BSF layer may be included. A plurality of solar cell layers can be stacked to form one solar cell layer. In this case, a tunnel junction layer is formed between the solar cell layers. A material such as InGaP, GaAs, or InGaAs can be used for the base layer, a material such as InGaP, GaAs, InGaAs, or AlInGaP can be used for the emitter layer, and a material such as AlInGaP, AlInP, or AlGaAs can be used for the window layer. For the contact layer 103, GaAs, InGaAs, or the like can be used.

Next, as shown in FIG. 1B, a SiO ₂ insulating film 108 of about 50 nm is formed on the surface of the compound semiconductor wafer 105 as a protective layer. The insulating film 108 may be any material that is insoluble in a photoresist, a developer and a resist stripper and can be etched. A metal oxide film such as SiO ₂ or TiO ₂ or a metal such as Si ₃ N ₄ or AlN. A nitride film can be used. The thickness of the insulating film 108 may be a thickness that can sufficiently protect the base,
In the plating step, it is preferable to make the plating solution as thin as possible so that the plating solution is sufficiently distributed around the laminated electrode.

  Next, after a photoresist 109 is formed on the insulating film 108, an opening 109a is formed by photolithography to obtain a light-receiving surface electrode pattern as shown in FIG.

  Next, as shown in FIG. 1D, a part of the insulating film 108 is removed by etching using the photoresist 109 as a mask to form an opening 108a. Etching is performed by wet etching using an acidic etching solution such as BHF (buffered hydrofluoric acid) or hydrochloric acid, or dry etching using a gas containing fluorine or chlorine. When depositing the laminated electrode, the laminated electrode 110 is prevented from coming into contact with the side surface of the insulating film 108, and the plating solution is sufficiently distributed around the laminated electrode when plating the coating film. Then, the insulating film 108 is over-etched to form the opening 108a so that the opening 108a of the insulating film is wider than the opening 109a of the photoresist.

  Next, a metal film to be the stacked electrode 110 is formed on the photoresist on which the light receiving surface electrode pattern is formed by vacuum deposition. An approximately 100 nm AuGe layer is formed by resistance heating evaporation, followed by an approximately 20 nm Ni layer, an approximately 100 nm Au layer and an approximately 5 μm Ag layer by EB evaporation. Thereafter, the photoresist and the metal film on the photoresist are removed by lift-off, whereby the stacked electrode 110 as shown in FIG. 1E is formed. Here, “lift-off” means that after performing photolithography, an electrode material is formed by vacuum deposition or the like, and finally the resist and the electrode material formed on the resist are removed to obtain a desired electrode pattern. Say.

  Thereafter, as shown in FIG. 1F, a coating film 111 is formed on the surface of the laminated electrode 110 by plating using the insulating film 108 as a mask. Using a non-cyanide type Au plating solution, an Au coating film of about 30 nm is formed. The plating may be either electrolytic plating or electroless plating.

  In the present invention, a coating layer is formed using a resist pattern for forming a laminated electrode as it is as a plating mask before lift-off in that a coating film is formed using an insulating film formed in advance after lift-off as a plating mask. This is different from Patent Document 1 described above.

Next, after the insulating film 108 is removed, the light-receiving surface electrode is sintered at 300 ° C. to 450 ° C. in an inert gas atmosphere such as nitrogen (N ₂ ). Subsequently, using the light-receiving surface electrode 104 as a mask, the contact layer 103 is removed by etching to obtain a shape in which the contact layer 103a is formed only under the light-receiving surface electrode as shown in FIG. Etching is performed using an aqueous ammonia / hydrogen peroxide solution.

  Next, as shown in FIG. 1H, a mesa etching pattern is formed on the surface of the solar cell element by photolithography, and the compound semiconductor layer in the mesa etching portion is removed by etching to expose the substrate. Etching is performed using an aqueous hydrochloric acid solution and an aqueous ammonia / hydrogen peroxide solution. Subsequently, the mesa etching pattern 102a is diced and cut into a desired cell shape.

Next, an Au layer of about 300 nm and an Ag layer of about 1 μm are formed on the back surface of the substrate as the back electrode 106 by EB vapor deposition. Subsequently, a TiO ₂ film of about 60 nm and an Al ₂ O ₃ film of about 90 nm are formed as an antireflection film 107 on the surface of the solar cell layer by EB vapor deposition. The film thickness may be an appropriate thickness depending on factors such as the refractive index of the film and the refractive index of the surface of the solar cell element. Finally, sintering of the back electrode and the antireflection film is performed in the same procedure as the sintering of the light receiving surface electrode to obtain the solar cell element shown in FIG.

<Embodiment 2>
FIG. 2 is a diagram showing each step of the method for manufacturing the solar cell element in the second embodiment of the present invention. A compound semiconductor wafer 205 shown in FIG. 2A has a configuration similar to that of the first embodiment. The second embodiment is characterized in that the protective film 208 is configured to be thicker than the thickness of the laminated electrode.

As shown in FIG. 2B, the protective film 208 is formed to be thicker than the laminated electrode. An Al film of about 6 μm, for example, is formed on the contact layer 203 by screen printing using an Al paste. The protective film may be any material that is insoluble in a photoresist, a developer, and a resist stripper and that can be etched, and its conductivity is not limited. A metal such as Al or Sn, a metal oxide film such as SiO ₂ or TiO ₂ , or a metal nitride film such as Si ₃ N ₄ or TiN can be used.

  Next, after forming a photoresist 209 on the protective film 208, an opening 209a is formed by photolithography to obtain a light-receiving surface electrode pattern as shown in FIG.

  Next, as shown in FIG. 2D, a part of the protective film 208 is removed by etching using the photoresist 209 as a mask to form an opening 208a. Etching is performed by wet etching using an acidic etching solution such as BHF (buffered hydrofluoric acid) or hydrochloric acid, or dry etching using a gas containing fluorine or chlorine. When the laminated electrode is deposited, the laminated electrode 210 is prevented from coming into contact with the side surface of the protective film 208, and the plating solution is sufficiently distributed around the laminated electrode when plating the coating film. Then, the protective film 208 is over-etched so that the opening 208a of the protective film is wider than the opening 209a of the photoresist.

  Next, a metal film to be the laminated electrode 210 is formed by vacuum deposition on the photoresist on which the light-receiving surface electrode pattern is formed. An approximately 100 nm AuGe layer is formed by resistance heating evaporation, followed by an approximately 20 nm Ni layer, an approximately 100 nm Au layer and an approximately 5 μm Ag layer by EB evaporation. Thereafter, the photoresist and the metal film on the photoresist are removed by lift-off to form a laminated electrode 210 as shown in FIG.

  Thereafter, as shown in FIG. 2 (f), a coating film 211 is formed which smoothly covers the entire surface of the solar cell element with a material insoluble in an etching solution for removing the contact layer. The coating film 211 was formed by applying a paste containing Ni by spin coating. Note that a paste (or ink) containing Au, Pt, Ni, Ti, or an alloy thereof can be used for the coating film 211, and dip, spin coating, or spraying can also be used as a coating method.

  A material 211 insoluble in an etching solution for removing the contact layer is formed so as to cover the entire surface of the compound solar cell smoothly. A paste (ink) of Au, Pt and Ni is applied by dipping, spin coating or spraying.

  Next, the shape of the light-receiving surface electrode 204 as shown in FIG. 2G is obtained by uniformly shaving the surface by etching, mechanical polishing, or CPM to expose the protective film 208.

After the removal of the protective film 208, a solar cell element is obtained in the same procedure as in the first embodiment. As shown in FIG. 2H, after the protective film 208 is removed, the light-receiving surface electrode is sintered at 300 ° C. to 450 ° C. in an inert gas atmosphere such as nitrogen (N ₂ ). Subsequently, using the light-receiving surface electrode 204 as a mask, the contact layer 203 is removed by etching to obtain a shape in which the contact layer 203a is formed only below the light-receiving surface electrode. Etching is performed using an aqueous ammonia / hydrogen peroxide solution.

  Next, as shown in FIG. 2 (i), a mesa etching pattern is formed on the surface of the solar cell element by photolithography, and the compound semiconductor layer in the mesa etching portion is removed by etching to expose the substrate. Etching is performed using an aqueous hydrochloric acid solution and an aqueous ammonia / hydrogen peroxide solution. Subsequently, the mesa etching pattern 202a is diced and cut into a desired cell shape.

Next, as shown in FIG. 2J, an Au layer of about 300 nm and an Ag layer of about 1 μm, for example, are formed on the back surface of the substrate 201 as the back electrode 206 by EB vapor deposition. Then, as the antireflection film 207, for example, a TiO ₂ film of about 60 nm and an Al ₂ O ₃ film of about 90 nm are formed on the surface of the solar cell layer by EB vapor deposition. The film thickness can be formed with an appropriate thickness depending on factors such as the refractive index of the film and the refractive index of the surface of the solar cell element. Finally, the back electrode and the antireflection film are sintered to obtain the compound semiconductor solar cell element shown in FIG.

  In Example 2, since the protective film 208 is configured to be thicker than the thickness of the laminated electrode, a coating film can be formed without using plating, and therefore, a material having no insulating property is used as the protective film. Is possible.

<Embodiment 3: Compound semiconductor wafer>
FIG. 3 is a cross-sectional view showing a compound semiconductor wafer used for a solar cell element. In the compound semiconductor wafer 305, a solar cell layer 302, a contact layer 303, and a compound semiconductor layer 308 insoluble in an etching solution for removing the contact layer are formed on a substrate 301. Substrate 301, solar cell layer 302, and contact layer 303 have the same configuration as the compound semiconductor wafer described in the first embodiment. In the compound semiconductor wafer, a compound semiconductor layer 308 made of semi-insulating InGaP to which no impurity is added is formed on the contact layer 303 with a thickness of, for example, about 50 nm. If the manufacturing method of the solar cell element is a method using the plating shown in the first embodiment, the thickness and the insulating property should be as thin and insulating as possible, and the polishing shown in the second embodiment is used. If it is a method, the thicker one is better and the insulation is not questioned. The compound semiconductor layer 308 can be formed using a material such as InP, InGaP, AlInP, AlInGaP, or GaP. In addition, the compound semiconductor layer may be insoluble in the etching solution for removing the contact layer and may have a different lattice constant from the contact layer or may have poor crystallinity as long as it does not pass the etching solution.

<Embodiment 4>
FIG. 4 is a cross-sectional view of a compound semiconductor solar battery in each step showing a method for manufacturing a semiconductor solar battery element using the compound semiconductor wafer of Embodiment 3. In FIG. 4A, a compound semiconductor wafer 405 has a solar cell layer 402 and a contact layer 403 formed on a substrate 401, and further a semi-insulating compound semiconductor layer 408 formed thereon. The steps after the formation of the light receiving surface electrode pattern are performed in the same procedure as in the first embodiment. Note that the semi-insulating compound semiconductor layer 408 can be removed by wet etching using hydrochloric acid.

  Next, as shown in FIG. 4B, after forming a photoresist 409 on the surface of the compound semiconductor layer 408, an opening 409a is formed by photolithography to obtain a light-receiving surface electrode pattern.

  Next, as shown in FIG. 1C, part of the compound semiconductor layer 408 is removed by etching using the photoresist 409 as a mask to form an opening 408a. Etching can be performed by wet etching using an acidic etching solution such as BHF (buffered hydrofluoric acid) or hydrochloric acid, or dry etching using a gas containing fluorine or chlorine.

  When the laminated electrode 410 to be formed later is vapor-deposited, the laminated electrode 410 is prevented from coming into contact with the side surfaces of the compound semiconductor layer 408, and the plating solution is formed around the laminated electrode when plating the coating film. Thus, the compound semiconductor layer 408 is over-etched so that the opening 408a of the compound semiconductor layer 408 is wider than the opening 409a of the photoresist.

  Next, a metal film to be the laminated electrode 410 is formed by vacuum deposition on the photoresist on which the light-receiving surface electrode pattern is formed. For example, an AuGe layer of about 100 nm is formed by resistance heating vapor deposition, and further, for example, a Ni layer of about 20 nm, an Au layer of about 100 nm and an Ag layer of about 5 μm are formed by EB vapor deposition. Thereafter, the photoresist and the metal film on the photoresist are removed by lift-off, whereby the stacked electrode 410 shown in FIG. 4D is formed.

  Thereafter, as shown in FIG. 4E, a coating film 411 is formed on the surface of the laminated electrode 410 by plating using the compound semiconductor layer 408 as a mask. As in the first embodiment, an Au coating film of about 30 nm can be formed using a non-cyanide type Au plating solution. Either electrolytic plating or electroless plating can be applied.

Next, after removing the compound semiconductor layer 408, the light-receiving surface electrode is sintered at 300 ° C. to 450 ° C. in an inert gas atmosphere such as nitrogen (N ₂ ). Then, using the light receiving surface electrode 404 as a mask, the contact layer 403 is removed by etching to obtain a shape in which the contact layer 403a is formed only under the light receiving surface electrode as shown in FIG. Here, an ammonia / hydrogen peroxide aqueous solution can be used for the etching.

  Next, as shown in FIG. 4G, a mesa etching pattern is formed on the surface of the solar cell element by photolithography, and the compound semiconductor layer in the mesa etching portion is removed by etching to expose the substrate. Etching is performed using an aqueous hydrochloric acid solution and an aqueous ammonia / hydrogen peroxide solution. Subsequently, the mesa etching pattern 402a is diced and cut into a desired cell shape.

Next, an Au layer of about 300 nm and an Ag layer of about 1 μm are formed on the back surface of the substrate as the back electrode 406 by EB vapor deposition. Subsequently, as the antireflection film 407, for example, a TiO ₂ film having a thickness of about 60 nm and a Al ₂ O ₃ film having a thickness of about 90 nm are formed on the surface of the solar cell layer by EB deposition. The film thickness can be formed with an appropriate thickness depending on factors such as the refractive index of the film and the refractive index of the surface of the solar cell element. Then, the back electrode and the antireflection film are sintered in the same procedure as that of the light receiving surface electrode to obtain the compound semiconductor solar cell element shown in FIG.

  The present invention employs the above-described manufacturing method of a solar cell element and a compound semiconductor wafer, thereby preventing etching of Ag occupying most of the light-receiving surface electrode, reducing a decrease in photoelectric conversion efficiency, It is useful as a compound semiconductor solar cell element.

DESCRIPTION OF SYMBOLS 101 Board | substrate, 102 Solar cell layer, 103 Contact layer, 104 Light-receiving surface electrode, 105 Compound semiconductor wafer, 106 Back surface electrode, 107 Antireflection film, 108
Insulating film, 109 photoresist, 110 laminated electrode, 111 coating film.

Claims (11)

In a method for manufacturing a solar cell element, including a compound semiconductor wafer in which a solar cell layer and a contact layer are sequentially formed on a substrate,
Forming a protective film on the contact layer;
Forming an electrode pattern by photolithography after applying a photoresist on the protective film; and
Removing the protective film by etching using the photoresist as a mask;
Forming a laminated electrode by lift-off after laminating the electrode material on the contact layer by vapor deposition; and
Forming a light-receiving surface electrode by forming a coating film with a material insoluble in an etching solution for removing a contact layer on the surface of the laminated electrode using the protective film as a mask;
Removing the protective film;
Removing the contact layer by etching using the light-receiving surface electrode as a mask;
The manufacturing method of the solar cell element characterized by including. The method for manufacturing a solar cell element according to claim 1, wherein the material insoluble in the etching solution for removing the contact layer is a conductor made of Au, Pt, NiTi, or an alloy thereof. The method for manufacturing a solar cell element according to claim 1, wherein the protective film has an insulating property. The method for manufacturing a solar cell element according to claim 1, wherein the coating film of a material insoluble in an etching solution for removing the contact layer is formed by plating.   A coating film of a material insoluble in an etching solution for removing the contact layer is formed by a method in which the protective film is exposed by etching or polishing after forming the material so as to cover the entire surface of the solar cell element. The method for producing a solar cell element according to claim 1, wherein:   In a solar cell element including a compound semiconductor wafer in which a solar cell layer and a contact layer are sequentially formed on a substrate, a compound semiconductor layer insoluble in an etching solution for removing the contact layer is formed on the contact layer. A compound semiconductor wafer for solar cell elements. Forming an electrode pattern by photolithography after applying a photoresist on the compound semiconductor wafer for solar cell elements according to claim 6; and
Etching the compound semiconductor layer using the photoresist as a mask;
Forming a laminated electrode by lift-off after laminating electrode materials by vapor deposition; and
Forming a light-receiving surface electrode by coating the surface of the laminated electrode with the compound semiconductor layer as a mask and coating a material insoluble in an etching solution for removing the contact layer;
Removing the compound semiconductor layer;
And a step of removing the contact layer by etching using the light-receiving surface electrode as a mask.   8. The method for manufacturing a solar cell element according to claim 7, wherein the material insoluble in the etching solution for removing the contact layer is a conductor made of Au, Pt, Ni, Ti, or an alloy thereof.   The method for manufacturing a solar cell element according to claim 8, wherein the compound semiconductor layer has an insulating property.   The method for manufacturing a solar cell element according to claim 7, wherein the coating film made of a material insoluble in an etching solution for removing the contact layer is formed by plating.   The coating of the material insoluble in the etching solution for removing the contact layer is performed by a method of exposing the surface of the compound semiconductor layer by etching or polishing after forming the material so as to cover the entire surface of the solar cell element. It forms, The manufacturing method of the solar cell element of Claim 7 characterized by the above-mentioned.

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