JP2001053299A - Manufacture of solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a solar cell, where wasted material can be least. SOLUTION: A surface support board 170' is bonded to the surface of a solar cell element film 120 for the formation of an element unit 1. A rear support board 280 is bonded on the rear of a solar cell element film 220 for the formation of an element unit 2. The laminated units 1 and 2 are pasted together to make the solar cell element films 120 and 220 confront each other, by which a laminated solar cell 10 where the solar cell element films 120 and 220 are sandwiched between the surface support board 170' and the rear support board 280 is formed. The element units 1 and 2 are pasted together to obtain the solar cell 10, so that an element unit which contains a defective solar cell element film is omitted in advance, only the element units which contain non- defective solar cell element films can be pasted together, and therefore the wasted material can be least.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a solar cell having a plurality of solar cell element films.

[0002]

2. Description of the Related Art In the field of solar cells, the development of solar cells (so-called tandem solar cells) in which a plurality of solar cell element films are laminated has been advanced in order to increase the energy conversion efficiency. In such a solar cell, a solar cell element film (for example, a single crystal Si (silicon) solar cell element film) that absorbs light of a relatively short wavelength is disposed near the light receiving surface, and light of a relatively long wavelength is emitted. By disposing the absorbing solar cell element film (for example, single-crystal SiGe (silicon germanium) solar cell element film) at a position away from the light receiving surface, light in a wide wavelength band is efficiently absorbed. .

Conventionally, as a method of manufacturing such a solar cell, a method of sequentially forming a plurality of layers of solar cell element films on a substrate by using a plasma CVD method or the like has been used for an amorphous silicon solar cell. ing.

In recent years, in order to increase the light receiving area of a solar cell, a solar cell in which a plurality of solar cell element films are two-dimensionally arranged (a so-called two-dimensionally integrated solar cell) has been developed. . Conventionally, as a method for manufacturing such a solar cell, a method has been used in which a plurality of solar cell element films are arranged on a large-sized substrate by using a plasma CVD method or the like.

[0005]

However, in the above-mentioned conventional methods of manufacturing a tandem-type and two-dimensionally integrated solar cell, if one of the formed solar cell element films has a defect, the entire solar cell is defective. Must be discarded as defective. Accordingly, even a solar cell element film having no defect is discarded, and there is a problem that the material is wasted.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a method of manufacturing a solar cell capable of minimizing material waste.

[0007]

A method of manufacturing a solar cell according to the present invention comprises the steps of forming a plurality of element units each having a solar cell element film supported by a supporting substrate, and combining the plurality of element units to form a solar cell. Forming a step.

Further, another method of manufacturing a solar cell according to the present invention includes a step of forming a plurality of element units each having a solar cell element film supported by a supporting substrate; and a step of forming at least two element units among the plurality of element units. Are stacked so that the solar cell element films face each other.

In another method for manufacturing a solar cell according to the present invention, a step of forming an element unit in which a solar cell element film is supported by a support substrate, and a step of bonding a plurality of element units to a common surface of a common member And the step of performing.

In the method of manufacturing a solar cell according to the present invention, when a defect occurs in a certain solar cell element film, an element unit including the solar cell element film is excluded as a defective product.
A solar cell is formed by combining only element units including a solar cell element film without defects. In addition, since the solar cell element film is supported by the support substrate, the solar cell element film can be combined even if the solar cell element film is thin (for example, about 1 μm).

In another method for manufacturing a solar cell according to the present invention, when a defect occurs in a certain solar cell element film, an element unit including the solar cell element film is excluded as a defective product, and no defect is found. Only the element unit including the solar cell element film is bonded to form a solar cell.

In another method for manufacturing a solar cell according to the present invention, when a defect occurs in a certain solar cell element film, an element unit including the solar cell element film is excluded as a defective product, and no defect is found. Only an element unit including a solar cell element film is bonded to a common member to form a solar cell.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

[First Embodiment] A method of manufacturing a tandem solar cell according to a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a process chart showing a method for manufacturing a tandem solar cell according to the first embodiment. FIG.
FIGS. 7A to 7D are cross-sectional views for each step for explaining the manufacturing method shown in FIG.

In the first embodiment, an element unit 1 including a single-crystal Si (silicon) solar cell element film 120;
A tandem solar cell having a two-layer structure is manufactured by bonding an element unit 2 including a single-crystal SiGe (silicon germanium) solar cell element film.

First, a method of manufacturing the element unit 1 shown in steps S10 to S28 in FIG. 1 will be described. here,
A semiconductor substrate 100 made of, for example, single crystal Si having a (100) crystal plane as shown in FIG. 2A is used.
For anodizing, single-crystal Si may be, for example, B
Preferably, a p-type impurity such as (boron) is added at about 10 ¹⁹ atms / cm ³ and has a specific resistance of about 0.01 to 0.02 Ω · cm.

As shown in FIG. 2B, the semiconductor substrate 1
The porous layer 110 is formed on the surface of No. 00 by anodization (S10). The anodization method is a method in which electricity is supplied in a hydrofluoric acid solution using the semiconductor substrate 100 as an anode. For example, “Surface Technology Vol. 46. No. 5.p8-1” by Ito et al.
3, 1995 [Anodic formation of porous silicon] ". In this method, a semiconductor substrate 10 on which a porous layer is to be formed between two electrolytic solution layers
0, and a platinum electrode connected to a direct current is placed in both electrolytic solution tanks. Then, the electrolytic solution is put into both the electrolytic solution tanks, and a DC voltage is applied to the platinum electrode, and the semiconductor substrate 10
0 is an anode and a platinum electrode is a cathode. Thereby, one surface of the semiconductor substrate 100 is eroded and becomes porous.

Specifically, for example, HF (hydrogen fluoride): C ₂ H ₅ OH (ethanol) = 1: 1 (49% HF solution and 95% C ₂ H ₅ OH solution as an electrolytic solution (anodizing solution)) Using an electrolytic solution having a volume ratio of, for example, 1 mA / cm
By performing the first stage anodization at a current density of about ² for 8 minutes, a low porosity porous layer 112 having a thickness of, for example, about 1.7 μm and a small porosity (eg, about 16%) is formed. Next, a second stage of anodization is performed at a current density of, for example, 7 mA / cm ² for 8 minutes, for example, to a thickness of 6.3 μm.
A medium porosity porous layer 113 having a medium porosity of about m (for example, about 26%) is formed. Then, for example, 200m
By performing the third step of anodization at a current density of A / cm ² for several seconds, for example, the high porosity porous layer 114 having a thickness of about 0.05 μm and a large porosity (eg, about 60 to 70%) can be obtained. Form. Thus, a porous layer 110 including three porous layers 112, 113, and 114 having a thickness of about 8 μm and different porosity is formed.

Next, hydrogen annealing is performed at a temperature of, for example, 1100 ° C. for 30 minutes to close a hole present on the surface of the porous layer 110, and then a gas such as SiH ₄ (silane) is used at a temperature of, for example, 1070 ° C. A single-crystal Si layer is epitaxially grown on the porous layer 110 under the conditions to form a single-crystal Si solar cell element film 120 having a thickness of 1 to 50 μm (S1).
2). More specifically, the single crystal Si on the porous layer 110
The layer is doped with, for example, B (boron) of about 10 ¹⁹ atms / cm ³ to form the p ⁺ layer 121, and B is again doped on the p ⁺ layer 121 (however, the amount of doping is reduced). Crystal S
The i-layer is epitaxially grown to a thickness of 1 to 10 μm to form a p-layer 122.

Next, as shown in FIG. 2D, an oxide film 13 is formed on the solar cell element film 120 by, for example, thermal oxidation.
After forming 0 in a predetermined pattern, the p-type layer 122 is doped with an n-type impurity (P (adjacent) or the like) using the patterned oxide film 130 as a mask to obtain n ⁺
The layer 123 is formed. On this n ⁺ layer 123, for example, T
An anti-reflection film 150 made of iO ₂ (titanium oxide) is formed. Further, the electrode opening 151 is formed in the anti-reflection film 150.
Is formed, and a surface electrode 160 made of, for example, Ti / Pd / Ag (titanium / palladium / silver) is selectively formed in the electrode opening 151. Here, during the above-described hydrogen annealing and epitaxial growth, the porous layer 1
In FIG. 10, the portion having a high porosity (that is, FIG.
The high porosity porous layer 114) in (B) has a higher porosity, and the layer having the lowest tensile strength, ie, the separation layer 11
Becomes 1. However, the separation layer 111 has such a tensile strength that the solar cell element film 120 does not separate from the semiconductor substrate 100.

After forming the surface electrode 160, FIG.
As shown in (1), the surface support substrate 170 made of, for example, PET (polyethylene terephthalate) is adhered to the surface of the solar cell element film 120 using the adhesive film 171 (S14). Note that the surface support substrate 170 needs to have mechanical strength that can withstand the later-described bonding operation of the element unit 1 and the element unit 2, and the thickness thereof is 0.1.
mm or more is desirable. In addition, the adhesive film 1
For example, a PET substrate 71 coated with a temperature-sensitive adhesive Intelimer (manufactured by Nitta Co., Ltd.) developed by Landic Corporation in the United States is used. Adhesion at room temperature is 30g / 2
Although it is 5 mm, it becomes 3 g / 25 mm or less at 60 ° C., resulting in an adhesive strength of 1/10 or less.

Subsequently, as shown in FIG. 3B, the separation layer 111 of the porous layer 110 is broken, and the semiconductor substrate 100 is separated from the solar cell element film 120 (S16). At the time of peeling, for example, a method of applying a tensile stress between the surface support substrate 170 and the semiconductor substrate 100, immersing the semiconductor substrate 100 in a solution such as water or ethanol, and irradiating ultrasonic waves to form the separation layer 111 A method of peeling with a reduced strength or a method of applying a centrifugal force to weaken the strength of the separation layer 111 is used. Further, a plurality of the above three methods may be used together. After the separation of the semiconductor substrate 100, the solar cell element film 120 is supported only by the surface support substrate 170.

Subsequently, after the porous layer 110A on the back surface of the solar cell element film 120 is removed by etching, as shown in FIG.
For example, Ti / Pd /
The back electrode 161 made of Ag is formed (S18).

Next, as shown in FIG. 4A, for example, PET or PC
The back support substrate 180 made of (polycarbonate) is bonded (S20). The wax 18 used for bonding the solar cell element film 120 and the back support substrate 180 is used.
No. 1 (FIG. 4B) melts at 65 ° C.

Next, as shown in FIG. 4B, the solar cell element film 120 is heated to 60.degree.
(FIG. 4A), the adhesive force of the solar cell element film 1 was reduced.
The surface support substrate 170 is peeled from the surface of the substrate 20 (S2).
2).

Subsequently, after a lead wire (not shown) is connected to the surface electrode 160 by soldering (S24), FIG.
As shown in (C), a surface support substrate 170 ′ made of transparent plastic is bonded to the surface of the solar cell element film 120 (S26). For adhesion between the surface support substrate 170 ′ and the solar cell element film 120, for example, a transparent epoxy resin (adhesive) is used.

Further, the solar cell element film 120 is heated to 70 ° C., and the solar cell element film 120 and the back support substrate 180 are heated.
Of the wax 181 between the solar cell element films 12
Then, the back support substrate 180 is peeled from 0 (S28). Thus, the element unit 1 in which the single-crystal Si solar cell element film 120 is held on the surface support substrate 170 ′ as shown in FIG. 4D is completed. The surface support substrate 1
70 'corresponds to a specific example of the "support substrate" of the present invention.

Next, a method of manufacturing the second element unit 2 shown in steps S30 to S42 of FIG. 1 will be described. FIG.
The semiconductor substrate 200 shown in (A) is made of single-crystal Si to which a p-type impurity is added, similarly to the semiconductor substrate 100 of the element unit 1. First, as shown in FIG. 5B, a porous layer 210 is formed on the surface of the semiconductor substrate 200 by anodization (S30). The details of the anodization method are omitted.

Next, hydrogen annealing is performed at a temperature of, for example, 1100 ° C. for 30 minutes to close a hole existing on the surface of the porous layer 110, and then a SiH ₄ gas and a GeF ₄ (germanium fluoride) gas are used. Single-crystal SiG on the porous layer 210
e (silicon germanium) is grown and single crystal SiG
e The solar cell element film 220 is formed (S32). Specifically, the single crystal SiGe layer on the porous layer 210 is doped with, for example, about 10 ¹⁹ atms / cm ³ of B to form the p ⁺ layer 221.
And a single-crystal SiGe layer is again formed on this p ⁺ layer 221.
A p layer 222 is formed by epitaxial growth of up to 49 μm. Further, after an oxide film 230 is formed on the single crystal SiGe layer by, for example, thermal oxidation and patterned, the n-type impurity (for example, P) is doped into the p layer 222 using the patterned oxide film 230 as a mask. ^{The +} layer 223 is formed. An oxide film 230, an antireflection film 250, and a surface electrode 260 are formed on the surface of the solar cell element film 220 in the same manner as in the method of manufacturing the element unit 1.

Next, as shown in FIG. 6A, a surface support substrate 270 made of, for example, PET (polyethylene terephthalate) is adhered to the surface of the solar cell element film 220 using the adhesive film 271 (S34). ). The material of the adhesive film 271 is the same as that of the adhesive film 171 used in the method of manufacturing the element unit 1, and the adhesive force is large at room temperature and decreases at 50 ° C.

Subsequently, the porous layer 210 is broken, and the semiconductor substrate 200 is separated from the solar cell element film 220 (S
36). The peeling method is the same as the peeling of the semiconductor substrate 100 in the method of manufacturing the element unit 1 (Step S16).

Subsequently, after the porous layer 210 on the back surface of the solar cell element film 120 is removed by etching, as shown in FIG. Ti / Pd / A
The back electrode 261 made of g is formed (S38). The back electrode 261 is connected to a lead wire (not shown) by soldering.

Next, as shown in FIG. 6C, an epoxy resin 281 is formed on the back surface of the solar cell element film 220.
Using (FIG. 6D), a back support substrate 280 made of, for example, PET or PC is bonded (S40).

Next, as shown in FIG. 6D, the solar cell element film 220 is heated to 60 ° C.
Is reduced, and the surface support substrate 270 is separated from the surface of the solar cell element film 220 (S42). Thus, the element unit 2 in which the single-crystal SiGe solar cell element film 220 is supported by the back support substrate 280 is formed. Here, the back support substrate 280 corresponds to a specific example of the “support substrate” of the present invention. The surface support substrate 270 separated in FIG. 6D corresponds to a specific example of the “support member” of the present invention.

A method of bonding the element units 1 and 2 The two element units 1 and 2 manufactured by the above-described steps.
Is, as shown in FIG. 7A, the solar cell element film 120.
Are bonded together with the solar cell element film 220 facing each other (S44). The adhesive 125 (FIG. 7B) used for bonding the element units 1 and 2 is, for example, a transparent epoxy resin. The back electrode 161 of the solar cell element film 120 and the front electrode 260 of the solar cell element film 220 are electrically connected by the solder bump B (FIG. 7B).

In this manner, as shown in FIG. 7B, the single crystal Si solar cell element film 120 and the single crystal SiGe solar cell element film 220 are connected in series, and two substrates (surface support substrate 170 ') The tandem solar cell 10 having a two-layer structure sandwiched between the tandem solar cell 10 and the back support substrate 280) is obtained.

In the tandem solar cell 10 having the two-layer structure configured as described above, the transparent surface supporting substrate 170 ′
Is incident on the solar cell element film 120. Of the incident light, light having a relatively short wavelength is absorbed by the single-crystal Si solar cell element film 120, and the generated photovoltaic power is output via the front electrode 160 and the back electrode 161. In addition, light having a relatively long wavelength that has passed through the single-crystal Si solar cell element film 120 is absorbed by the single-crystal SiGe solar cell element film 220, and the generated photovoltaic power passes through the front electrode 260 and the back electrode 261. Output.

In the tandem solar cell 10 having a two-layer structure shown in FIG. 7B, a single-crystal Si solar cell element film 120 that absorbs light having a relatively short wavelength is arranged on the side closer to the light incident surface. Since the single-crystal SiGe solar cell element film 220 that absorbs light having a long wavelength is disposed and arranged on a side far from the light incident surface, light in a wide wavelength band can be efficiently absorbed.

FIG. 8 shows a method for manufacturing a tandem solar cell having a three-layer structure by adding one more solar cell element film to a tandem solar cell having a two-layer structure. It is a process drawing showing a method. FIG. 9 and FIG. 10 are cross-sectional views for each step for explaining a method for manufacturing a solar cell having a three-layer structure. In the case of a three-layer structure, a wax that melts at 80 ° C. is used instead of the epoxy resin in the adhesive of FIG. 7B.

First, as shown in FIG. 9A, a tandem solar cell 10 having a two-layer structure was
(B)), the surface supporting substrate 170 ′ is peeled off from the surface of the solar electronic element film 120 by heating at or above the melting temperature (80 ° C.) (S48).

Next, an element unit 3 (FIG. 9B) to be newly laminated on the solar cell 10 is manufactured by the steps S50 to S68 in FIG. Since the manufacturing process of the element unit 3 is almost the same as the manufacturing process of the element unit 1, a cross-sectional view for each process is omitted.

The element unit 3 shown in FIG. 9B is formed in the same manner as the element unit 1. That is, a porous layer is formed on a semiconductor substrate (not shown) (S50),
SiC (silicon carbide) is grown thereon to form a SiC solar cell element film 320 (S52). Specifically, the SiC layer is doped with B on the porous layer of the semiconductor substrate to form ap ⁺ layer 321, and the Si ⁺ layer 321 is formed on the p ⁺ layer 321 again.
C layer is epitaxially grown by 1 to 5 μm to form a p layer 322.
And Further, for example, an oxide film SiO ₂ 3 is formed on the SiC layer.
After forming and patterning the N ⁺ layer 30, the p ⁺ layer 322 is doped with an n-type impurity (for example, P) using the patterned oxide film 330 as a mask, thereby forming the n ⁺ layer 3.
23 are formed. On the surface of the solar cell element film 320, an oxide film 330,
An anti-reflection film 350 and a surface electrode 360 are formed.

Subsequent steps S54 to S68 correspond to step S14 in the manufacturing process of the element unit 1.
Through S28. That is, a surface support substrate (not shown) made of, for example, PET is bonded to the surface of the solar cell element film 320 by using the adhesive film 371 whose adhesive strength is reduced at 50 ° C. (S54). Subsequently, the semiconductor substrate (not shown) is separated from the solar cell element film 320 (S56). Further, on the back surface of the solar cell element film 320,
For example, a back electrode 361 made of Ti / Pd / Ag is formed (S58), and the back electrode 361 and a lead wire (not shown) are connected by soldering.

Next, on the back surface of the solar cell element film 320, 7
A back support substrate (not shown) made of, for example, PET or PC is bonded using a wax that melts at 0 ° C. (S60). Subsequently, the solar cell element film 320 is heated to 60 ° C. to reduce the adhesive strength of the adhesive film 371, and the surface support substrate 370 is peeled from the surface of the solar cell element film 320 (S62).

Next, after the surface electrode 360 and the lead (not shown) are connected to each other by soldering (S64), the surface support substrate 370 made of a transparent member is connected to the solar cell element film 3.
20 (S66). At this time, a transparent epoxy resin is used as the adhesive. Further, the solar cell element film 120 is heated to 70 ° C.
The wax between the substrate 20 and the back support substrate (not shown) is melted, and the back support substrate (not shown) is separated from the solar cell element film 120 (S68). Thus, FIG.
The element unit 3 in which the SiC solar cell element film 320 is held on the surface support substrate 370 as shown in FIG. Here, the element unit 3 corresponds to a specific example of “another element unit” of the present invention.

The element unit 3 configured as described above and the solar cell 10 (with the surface support substrate 170 removed) are
As shown in FIG. 9B, the solar cell element film 320 and the solar cell element film 120 are attached so that the back surface and the front surface of the solar cell element film 120 face each other. As the adhesive 325 (FIG. 10), for example, a transparent epoxy resin is used. Further, the back electrode 361 of the solar cell element film 320 and the front electrode 160 of the solar cell element film 120 are connected by the solder bump B.

As a result, as shown in FIG. 10, the SiC solar cell element film 320, the single crystal Si solar cell element film 120, and the single crystal SiGe solar cell element film 220 are connected in series (in order from the light incident side). Thus, a tandem solar cell 11 having a three-layer structure is obtained. Further, the three solar cell element films 320, 120, and 220 are formed of two substrates 370, 18
0 is sandwiched from both sides in the stacking direction.

FIG. 11 shows three solar cell element films 320,
It is a figure showing the connection state of 120,220. The solar cell element films 320, 120, and 220 are connected in series by solder bumps B. Three solar cell element films 32
The front surface electrode 360 and the back surface electrode 261 located at both ends in the stacking direction of 0, 120, and 220 are formed in a comb shape. The back electrode 261 may be a flat electrode.

The operation of the tandem-type solar cell 11 having the three-layer structure thus configured is as follows. Among the sunlight transmitted through the surface support substrate 370, the light of short wavelength is S
The photoelectromotive force absorbed by the iC solar cell element film 320 and generated by the iC solar cell element film 320 is applied to the front electrode 360 and the back electrode 361.
Output from Of the light that has passed through the SiC solar cell element film 320, light of a medium wavelength is absorbed by the single crystal Si solar cell element film 120, and the photovoltaic power generated thereby is output from the front electrode 160 and the back electrode 161. You. The long-wavelength light that has passed through the single-crystal Si solar cell element film 120 is converted into a single-crystal SiGe solar cell element film 220.
The photoelectromotive force generated by the absorption is output from the front electrode 260 and the back electrode 261.

In the tandem solar cell 11 having a three-layer structure shown in FIG. 10, a SiC solar cell element film 320 that absorbs short-wavelength light is disposed on the side closer to the light incident surface, and absorbs long-wavelength light. The single crystal SiGe solar cell element film 220 is disposed farthest from the light incident surface, and the single crystal Si solar cell element film 120 that absorbs light of a medium wavelength is disposed at an intermediate position. Therefore, light in a wide wavelength band can be efficiently absorbed.

By repeating the process of FIG. 8, that is, by peeling off the front support substrate (or the back support substrate) of the tandem solar cell and bonding another element unit, a four-layer structure or more is obtained. A solar cell can be formed. The types of the solar cell element films to be laminated may be the same or different.

As described above, according to the method of manufacturing a tandem solar cell according to the first embodiment, a solar cell element film and a support substrate are bonded together to form a multilayer solar cell. Since a tandem solar cell having an element film is manufactured, if a defect occurs in the solar cell element film, an element unit including the solar cell element film is excluded as a defective component, and a normal solar cell element film is formed. Can be bonded together. Therefore, all the solar cell element films having no defect can be effectively used, and waste of materials can be minimized.

In addition, it is possible to prepare various types of element units composed of a solar cell element film and a supporting substrate in advance, and to bond them according to the application. In this way, various solar cells can be easily manufactured. Further, since the solar cell element films 120 and 220 are supported by the support substrates 170 and 280, even if the solar cell element films 120 and 220 are thin (for example, about 1 μm).
Lamination work is possible.

Further, since the surface supporting substrate 170 can be peeled off from the already stacked solar cells 10 and another stacked element unit can be bonded, a solar cell having a three-layer structure or more can be easily manufactured. .

In the present embodiment, the solar cell 11
Has a three-layer structure including a SiC solar cell element film, a single-crystal Si solar cell element film, and a single-crystal SiGe solar cell element film, but other types of solar cells may be combined.

In this embodiment, the adhesive tape 171 is used for bonding the solar cell element film 120 and the surface support substrate 170. However, instead of the adhesive tape, a solvent (for example, a methyl alcohol or ketone solvent) is used. , A hydrocarbon solvent, etc.). In this case, as shown in FIG. 12, if a large number of through holes 175 are formed in the surface support substrate 170,
Since the solvent supplied from the surface side of the wax 0 spreads over the entire surface of the wax 174, the wax 174 can be dissolved promptly. In addition, as shown in FIG. 13, wax 176 may be applied to the bonding surface of the surface support substrate 170, for example, on lattice points. By doing so, the solvent that has flowed into the gap between the surface support substrate 170 and the solar cell element film 120 spreads sufficiently to all of the wax 176, so that the wax 176 can be immediately dissolved.

[Second Embodiment] Next, a second embodiment of the present invention will be described.
A method for manufacturing a tandem solar cell according to the embodiment will be described. 14 and 15 are cross-sectional views illustrating a method of manufacturing a tandem solar cell according to the second embodiment. As shown in FIG. 14A, in this embodiment, a porous layer 510 is formed over the surface of a semiconductor substrate 500 made of, for example, single crystal Si containing a p-type impurity by anodization. Further, on the porous layer 510,
A single-crystal Si solar cell element film 520 including the p ⁺ layer 521, the p layer 522, and the n ⁺ layer 523 is formed. Next, as shown in FIG. 14B, the oxide film 530, the surface electrode 560, and the antireflection film 5 are formed on the solar cell element film 520.
Form 50. The steps up to this point are the same as those in the first embodiment, and a detailed description thereof will be omitted.

Further, as shown in FIG. 14C, a glass plate 570 is bonded to the surface of the solar cell element film 520 by using a wax 571 having a softening point of 49 ° C. In addition,
The adhesion between the solar cell element film 520 and the glass plate 570 is 60
C. (that is, a state in which the wax 571 is sufficiently softened). Next, as illustrated in FIG. 14D, the semiconductor substrate 500 is separated from the solar cell element film 520. The peeling method is the same as step S in the first embodiment.
Same as 16. Further, the porous layer 510 attached to the back surface of the solar cell element film 520 is removed by, for example, etching.

Subsequently, as shown in FIG. 15A, a back surface made of, for example, PET is formed on the back surface of the solar cell element film 520 by using a wax 581 having a softening point of 67 ° C. (FIG. 15B). The support substrate 580 is bonded. Subsequently, FIG.
As shown in (B), the solar cell element film 520 was heated at 60 ° C.
To soften the wax 571 (softening point 49 ° C.) between the solar cell element film 520 and the glass plate 570, peel the glass plate 570 from the solar cell element film 520, and form a surface electrode 560 and a lead wire (not shown). Are connected by soldering.

Thereafter, as shown in FIG. 15C, a glass plate 570 is bonded to the solar cell element film 520 again. The adhesive 572 for bonding the solar cell element film 520 and the glass plate 570 is, for example, a transparent epoxy resin. Further, the solar cell element film 520 is heated to 80 ° C. to soften the wax 581 (softening point 67 ° C.) between the solar cell element film 520 and the back support substrate 580, and Is peeled off. Next, a back electrode 261 (FIG. 16) is formed on the back surface of the solar cell element film 520.

The element unit 5 thus formed
Is superimposed on the element unit 2 manufactured by the manufacturing process of steps S30 to S42 of the first embodiment. The adhesive 225 used for bonding the element units 5 and 2 is, for example, a transparent epoxy resin. Further, the back electrode 261 of the solar cell element film 520 and the front electrode 260 of the solar cell element film 220 are connected by the solder bump B.

In this way, as shown in FIG.
A tandem solar cell 12 having a two-layer structure in which a single-crystal Si solar cell element film 520 and a single-crystal SiGe solar cell element film 220 are connected in series and sandwiched between two substrates (a glass plate 570 and a back support substrate 280). Is formed.

According to the second embodiment described above,
Since the support substrate (glass plate 570) on the light incident side is made of glass having a high light transmittance, light can be more efficiently absorbed. Further, since the solar cell element film 520 and the substrates (the glass plate 570 and the back support substrate 580) are bonded to each other using a plurality of types of waxes having different softening points, which substrate is to be separated from the solar cell element film 520 is determined. Can be controlled by adjusting the temperature.

[Third Embodiment] Next, a third embodiment of the present invention will be described.
A method for manufacturing a solar cell having a single-layer structure according to the embodiment will be described. FIG. 17 and FIG. 18 are cross-sectional views for each step for describing the method for manufacturing a solar cell according to the third embodiment. As shown in FIG. 17A, in the third embodiment, a porous layer 410 is formed on the surface of a semiconductor substrate 400 made of, for example, p-type single crystal Si by anodization. Further, on the porous layer 410, the p ⁺ layer 42
1, single-crystal Si including p layer 422 and n ⁺ layer 423
A solar cell element film 420 is formed. Next, FIG.
As shown in FIG. 7, the oxide film 4 is formed on the solar cell element film 420.
30, the surface electrode 460 and the antireflection film 450 are formed. Since the steps up to here are the same as in the first embodiment,
Detailed description is omitted.

Next, as shown in FIG. 17C, an adhesive 47 which is relatively easy to peel off is attached to the solar cell element film 420.
1. (For example, adhesive strength 200 used for UV curable dicing tape D-210 manufactured by Lintec Co., Ltd.
The plastic film 470 is adhered using an adhesive of 0 g / 25 mm to 300 g / 25 mm). continue,
As illustrated in FIG. 17D, the semiconductor substrate 400 is separated from the solar cell element film 420. The peeling step is the same as step S16 of the first embodiment.

Next, as shown in FIG. 18A, a back electrode / reflection plate 461 made of, for example, Al, which covers the entire back surface of the solar cell element film 420, is formed by, for example, a sputtering method. Further, as shown in FIG. 18B, an adhesive 481 (for example,
A back support substrate 480 made of plastic is attached using epoxy resin).

Next, UV (ultraviolet) irradiation is performed through the plastic film 470 to reduce the adhesive strength of the adhesive 471 to 25 g / 25 mm to 5 g / 25 mm.
As shown in (C), the plastic film 470 is peeled off from the surface of the solar cell element film 420, and the adhesive remaining on the surface of the solar cell element film 420 is wiped off with, for example, alcohol. Further, after a lead wire (not shown) is soldered to the surface electrode 460, as shown in FIG. 18D, a transparent surface is formed on the surface of the solar cell element film 420 using an adhesive 472 (for example, epoxy resin). Plastic plate 4
Glue 70 '.

In this way, as shown in FIG. 18D, the solar cell element film 420 is
And single-layer solar cell 4 sandwiched by back support substrate 480
Is manufactured. If the plastic plate 470 'of the solar cell 4 having the single-layer structure is peeled off and overlapped with another solar cell element film as in the first embodiment, a tandem solar cell having a multilayer structure can be obtained. It is possible.

In the third embodiment described above, the UV
By irradiating, the adhesive strength is weakened, so that one kind of adhesive can be used as many times as front and back, and the solar cell element film 420 and the plastic film 470 are bonded using this. The peeling operation of 470 is easy.

[Modification of Third Embodiment] Next, a third embodiment will be described.
A modification of the embodiment will be described with reference to FIG. In this modification, as shown in FIG.
After the semiconductor substrate is separated from the solar cell element film 420, as shown in FIG. 19B, the back surface of the solar cell element film 420 is processed by anisotropic alkali etching to form many small irregularities 425 on the entire back surface. . Further, irregularities 42
5 over the entire back surface of the solar cell element film 420 including
1 film is formed by a sputtering method,
5 is formed.

Thereafter, as shown in FIG. 19C, a back support substrate 480 made of, for example, PET is bonded to the back surface of the reflector / back electrode 475 using an adhesive 481 (for example, epoxy resin). Further, similarly to the third embodiment, after the plastic film 470 is peeled off from the surface of the solar cell element film 420 and a lead wire (not shown) is connected to the surface electrode 460, the surface of the solar cell element film 420 is transparent. Is bonded. Thus, a single-layer solar cell 4 'as shown in FIG. 19C is obtained.

The surface of the solar cell 4 '(the plastic plate 47)
When light incident from 0 ′) passes through the solar cell element film 420 in the thickness direction and reaches the back surface, the light is reflected in various directions by the interface between the unevenness 425 and the reflector / back electrode 475. The light reflected in various directions on the back surface of the solar cell element film 420 is also reflected at the interface between the solar cell element film 420 and the plastic plate 470 ′. As a result, the light is transmitted through the solar cell element film 420. Proceed zigzag. Therefore, even if the thickness of the solar cell element film 420 is thin (for example, 1
(Approximately 0 μm), the length of the light traveling path can be lengthened, and the light can be absorbed more efficiently.

The plastic plate 470 ′ of the solar cell
By peeling off and stacking the solar cell element films, a tandem solar cell having a multilayer structure can be obtained.

[Fourth Embodiment] Next, a fourth embodiment of the present invention will be described.
A method for manufacturing a solar cell according to the embodiment will be described. In the fourth embodiment, the element unit 1 manufactured by the same steps as steps S10 to S28 in the first embodiment and the element unit 6 formed by another step are attached to each other. A tandem solar cell having a layer structure is manufactured. Hereinafter, only differences from the first embodiment will be described, and other description will be omitted.

FIG. 20 is a process chart showing a method for manufacturing a solar cell according to the fourth embodiment. 21 to 23 are cross-sectional views for explaining steps of the manufacturing method of FIG. Steps S70 to S70 in FIG.
Step 88 corresponds to step S1 in the first embodiment.
Since the steps from 0 to S28 are completely the same, the description is omitted. The element units 1 manufactured in the steps S70 to S88 are denoted by the same reference numerals as the element units 1 of the first embodiment.

Next, the element unit 6 is manufactured by steps S90 and S92 in FIG. First, as shown in FIG. 21A, a porous layer 610 is formed on the surface of a semiconductor substrate 600 made of, for example, p-type single crystal Si by anodization (S90). Further, FIG.
As shown in (B), a single-crystal SiGe solar cell element film 620 including a p ⁺ layer 621, a p layer 622, and an n ⁺ layer 623 is formed on the porous layer 610 (S92).
An oxide film 630, a surface electrode 660, and an anti-reflection film 650 are formed on the solar cell element film 620. The steps up to this point are the same as those in the first embodiment, and a detailed description thereof will be omitted.

Next, as shown in FIG. 22A, the element unit 1 and the element unit 6 were connected to the solar cell element film 12.
Attachment is performed so that 0,620 faces each other (S94).
At this time, the back electrode 161 of the solar cell element film 120 and the front electrode 660 of the solar cell element film 620 are connected by the solder bump B. Further, as the adhesive 125, for example, a transparent epoxy resin is used. As a result, FIG.
As shown in (B), the solar cell element films 120 and 620
Are connected in series and a structure sandwiched between the transparent surface support substrate 170 and the semiconductor substrate 600 is obtained.

Next, as shown in FIG. 23A, the semiconductor substrate 600 is separated from the solar cell element film 620 (S9).
5). As in the first embodiment, at the time of peeling, for example,
A method of applying a tensile stress between the surface supporting substrate 170 and the semiconductor substrate 600, a method of immersing the semiconductor substrate 600 in a solution such as water or ethanol, and irradiating an ultrasonic wave to reduce the strength of the porous layer 610 and to peel off the porous layer 610. Alternatively, a method of applying a centrifugal force to weaken the strength of the porous layer 610 and peeling the porous layer 610 is used.

Subsequently, after the porous layer 610A on the back surface of the solar cell element film 120 is removed by etching, the solar cell element film 62 is removed as shown in FIG.
0 is made of, for example, Al and a back electrode / reflection plate 670
Is formed by, for example, a sputtering method (S96).

Next, a back support substrate 680 made of, for example, plastic is bonded to the back surface (back electrode / reflector 670) of the solar cell element film 620 using an adhesive (for example, epoxy resin) (S97). Thus, FIG.
Single crystal Si solar cell element film 12 as shown in FIG.
Thus, a tandem-type solar cell having a two-layer structure in which 0 and a single-crystal SiGe solar cell element film 620 are arranged in series is obtained.

In the fourth embodiment described above, the element unit 6 is constituted by the solar cell element film 620 and the semiconductor substrate 600, and the semiconductor substrate 600 is peeled after the element units 1 and 6 are bonded. Therefore, there is no need to bond a surface support substrate or the like to the solar cell element film 620. Therefore, step S34 of the first embodiment
The step corresponding to FIG. 1 is not required, and the effect of reducing the number of steps by one can be obtained.

[Modification of Fifth Embodiment] Next, a method of manufacturing a two-dimensionally arranged solar cell according to a fifth embodiment of the present invention will be described. FIG. 24 is a process chart illustrating a method for manufacturing a solar cell according to the fifth embodiment. FIG. 25 to FIG. 27 are cross-sectional views for each step for explaining the manufacturing method of FIG.

In the manufacturing method according to the present embodiment, FIG.
A semiconductor substrate 700 made of, for example, single crystal silicon having a (100) crystal plane as shown in FIG.
As single-crystal silicon, for example, a p-type impurity such as B is added at about 10 ¹⁹ atms / cm ³ , and 0.01 to 0.02 Ω ·
Those having a specific resistance of about cm are preferable.

First, as shown in FIG. 25B, a porous layer 710 is formed on the surface of a semiconductor substrate 700 by the same anodization method as in the first embodiment. Next, for example, hydrogen annealing is performed at a temperature of 1100 ° C. for 30 minutes to close a hole present on the surface of the porous layer 710, and then SiH ₄
A single-crystal Si layer is epitaxially grown on the porous layer 710 under a temperature condition of, for example, 1070 ° C. by using such a gas to form a solar cell element film 720 of, for example, 1 to 50 μm.

On the porous layer 710, for example,
^A p ⁺ layer 722 is formed by doping at ¹⁹ atms / cm ³ . Next, about the p-type single crystal silicon layer on the p ⁺ layer 722 10
The p layer 723 is grown by μm epitaxial growth.
To form

Further, as shown in FIG.
Masking layer 723 with photoresist (not shown)
The p ⁺ layer 726 was formed by doping B at the portion where the plus electrode was to be formed. Further, P
(Next) was doped to form an n ⁺ layer 724, and a portion for forming a negative electrode was further doped with P to form an n ⁺⁺ layer 725.

Next, as shown in FIG. 26A, an oxide film 74 is formed on the surface of the solar cell element film 720 by, for example, thermal oxidation.
After 0 is formed in a predetermined pattern, an antireflection film 750 made of, for example, Si ₃ N ₄ is formed on the oxide film 740. Further, as shown in FIG. 26B, an electrode opening is formed in the antireflection film 750, and this opening is selectively made of, for example, Ti-Pd-Ag (titanium-palladium-silver alloy). The plus electrode 761 and the minus electrode 760 are formed (S104). Thus, the positive electrode 7
The element unit 7 in which the first electrode 61 and the negative electrode 762 are formed on one side is formed.

Next, as shown in FIG. 27 (A), a plurality of (here, three) element units 7 are arranged on a plane, and these element units 7 are shared as shown in FIG. 27 (B). It is bonded to the member 770 (S106). As the adhesive 701 for bonding the element unit 7 and the common member 770, for example, a transparent epoxy resin is used.

The common member 770 is a plate-like member made of a transparent insulating material. Also, the common member 7
70 is a plus electrode 7 between adjacent element units 7.
A conductor 771 that connects the negative electrode 61 and the negative electrode 760 is formed. The conductor 771 allows the common member 77
The element units 7 attached to 0 are connected in series.

Next, the semiconductor substrate 700 is peeled from the element unit 7 attached to the common member 770 (S10).
8). As in the first embodiment, at the time of peeling, for example,
A method of applying a tensile stress between the common member 770 and the semiconductor substrate 700, immersing the semiconductor substrate 700 in a solution such as water or ethanol, and irradiating ultrasonic waves to the porous layer 7
A method in which the strength of the porous layer 710 is reduced by applying a centrifugal force and a method in which the strength of the porous layer 710 is reduced is used.

Further, the porous layer 710 remaining on the back surface of the solar cell element film 720 is removed by etching or the like, and a common back support substrate 780 made of, for example, PET is bonded to the back surface of the solar cell element film 720 (S110). ). Thus, a two-dimensionally arranged solar cell as shown in FIG. 27C is obtained.

In the fifth embodiment described above, a two-dimensionally arranged solar cell is formed by attaching a plurality of element units 7 to a common support member. When a defect occurs, the element unit including the solar cell element film is excluded as a defective product, and only the element unit including the defect-free solar cell element film is bonded to a common support member to form a solar cell. be able to. Thus, material waste is minimized.

Further, a positive electrode 761 and a negative electrode 760 are formed on the same surface of the solar cell element film 720, and the positive electrode 7 of each solar cell element film 720 is formed by the conductor 771.
61 is the minus electrode 7 of the adjacent solar cell element film 760
Since the connection is made to 60, a plurality of solar cell element films 720 can be easily connected in series.

Although the present invention has been described with reference to some embodiments, the present invention is not limited to these embodiments, and various modifications are possible. For example, in each of the above embodiments, a solar cell element film made of single-crystal Si, single-crystal SiGe, SiC, or the like is used, but another solar cell element film (for example, a solar cell element made of amorphous Si, polycrystalline Si, GaAs, or the like) is used. Battery element film).

The material of the semiconductor substrate serving as a base for forming the solar cell element film may be Ge instead of Si. Note that the semiconductor substrate may be formed of a material (for example, Al ₂ O ₃ ) in which the lattice constant mismatch with Si is small. In this case, a Si solar cell element film can be heteroepitaxially grown on the Al ₂ O ₃ substrate.

Further, in each of the above embodiments, the front support substrate (or the back support substrate) and the solar cell element film are bonded by using an adhesive such as wax, but the front support substrate (or the back support substrate) is bonded. EV exhibiting adhesive strength under high temperature
If it is composed of A (ethylene vinyl acetate), it is not necessary to use an adhesive.

[0098]

As described above, according to the method for manufacturing a solar cell according to any one of claims 1 to 19, a solar cell is formed by combining a plurality of element units. If a defect occurs in a certain solar cell element film, the element unit including the solar cell element film is excluded as a defective product, and a solar cell is formed by combining only the element units including the non-defective solar cell element film. can do. Therefore, material waste can be minimized. In addition, since an element unit including a solar cell element film and a substrate can be formed in advance, the manufacturing process is simplified accordingly.

According to the method of manufacturing a solar cell according to any one of claims 2 to 14, a solar cell is formed by bonding at least two element units. When a defect occurs in the element film, the element unit including the solar cell element film is excluded as a defective product, and only the element unit including the non-defective solar cell element film is bonded to form a solar cell. it can. Therefore, material waste can be minimized.

According to the method for manufacturing a solar cell according to any one of the fifteenth to nineteenth aspects, a two-dimensionally arranged solar cell is formed by attaching a plurality of element units to a common member. Therefore, when a defect occurs in a certain solar cell element film, the element unit including the solar cell element film is excluded as a defective product, and only the element unit including the non-defective solar cell element film is bonded to the common member. Thus, a solar cell can be formed. Therefore,
Material waste can be minimized.

In particular, according to the method for manufacturing a solar cell according to the eighteenth aspect, a positive electrode and a negative electrode are formed on the same surface of the solar cell element film, and the positive electrode of each solar cell element film is adjacent to the solar cell element. Since the connection is made to the negative electrode of the film, each solar cell element film can be easily connected in series in a solar cell in which the solar cell element films are two-dimensionally arranged.

[Brief description of the drawings]

FIG. 1 is a process chart illustrating a method for manufacturing a solar cell according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining one step in the manufacturing method of FIG. 1;

FIG. 3 is a cross-sectional view for explaining a step following the step shown in FIG. 2;

FIG. 4 is a cross-sectional view for explaining a step following the step shown in FIG. 3;

FIG. 5 is a cross-sectional view for explaining a step following the step shown in FIG. 4;

FIG. 6 is a cross-sectional view for explaining a step following the step shown in FIG. 5;

FIG. 7 is a cross-sectional view for explaining a step following the step shown in FIG. 6;

FIG. 8 is a process chart illustrating a method for manufacturing a solar cell having a three-layer structure.

FIG. 9 is a cross-sectional view for explaining a step following the step shown in FIG. 8;

FIG. 10 is a cross-sectional view for explaining a step following the step shown in FIG. 9;

FIG. 11 is a schematic perspective view illustrating a layer structure of a three-layer structure.

FIG. 12 is a diagram showing an example of a surface support substrate that can be used in the first embodiment of the present invention.

13 is a diagram showing another example of the surface support substrate of FIG.

FIG. 14 is a cross-sectional view for explaining one step in the manufacturing method according to the second embodiment of the present invention.

FIG. 15 is an enlarged sectional view for explaining a step following the step shown in FIG. 14;

FIG. 16 is an enlarged cross-sectional view for explaining a step following the step shown in FIG. 15;

FIG. 17 is a cross-sectional view for explaining one step in the manufacturing method according to the third embodiment of the present invention.

FIG. 18 is an enlarged cross-sectional view for explaining a step following the step shown in FIG. 17;

FIG. 19 is a cross-sectional view for describing a modification of the manufacturing method according to the third embodiment of the present invention.

FIG. 20 is a process chart illustrating a method for manufacturing a solar cell according to the fourth embodiment of the present invention.

FIG. 21 is a cross-sectional view for explaining one step in the method of manufacturing the solar cell in FIG. 20.

FIG. 22 is an enlarged cross-sectional view for explaining a step following the step shown in FIG. 21.

FIG. 23 is an enlarged cross-sectional view for explaining a step following the step shown in FIG. 22.

FIG. 24 is a process chart illustrating the method of manufacturing the solar cell according to the fifth embodiment of the present invention.

FIG. 25 is a cross-sectional view for describing one step in the method of manufacturing the solar cell in FIG. 24.

FIG. 26 is an enlarged cross-sectional view for explaining a step following the step shown in FIG. 25.

FIG. 27 is an enlarged sectional view for explaining a step following the step shown in FIG. 26;

[Explanation of symbols]

1, 2, 3, 4, 5, 6, 7 ... element unit, 100,
200, 400, 500, 600, 700 ... semiconductor substrate, 110, 210, 410, 510, 610, 710
... porous layer, 120, 220, 320, 420, 52
0,620,720 ... solar cell element film, 160,26
0, 360, 460, 560, 660 ... surface electrode, 16
1, 261, 361, 461, 561 back electrode, 17
0 ', 270, 370, 570 ... Surface support substrate, 18
0, 280, 480, 580, 680, 780: back support substrate, 470 ': plastic plate, 570: glass plate.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takeshi Matsushita F-term (reference) 5F051 BA14 CB01 CB30 DA17 EA20 GA04 GA14 within 6-35 Kita-Shinagawa, Shinagawa-ku, Tokyo

Claims (19)

[Claims] 1. A method of manufacturing a solar cell including a plurality of solar cell element films, comprising: forming a plurality of element units each including a solar cell element film supported by a support substrate; Forming a solar cell by combining the methods. 2. A method for manufacturing a solar cell including a plurality of solar cell element films, comprising: forming a plurality of element units each including a solar cell element film supported by a support substrate; A step of laminating at least two element units among the above so that the solar cell element films face each other. 3. The step of laminating the solar cell element film,
Two element units of the plurality of element units,
3. The method for manufacturing a solar cell according to claim 2, further comprising a step of bonding the solar cell element films so as to face each other. 4. The step of laminating the solar cell element film includes: a step of peeling one of the support substrates from the at least two element units that have already been laminated; and a step of peeling off the support substrate. 4. The method for manufacturing a solar cell according to claim 3, further comprising: bonding another element film of the plurality of element units such that the solar cell element films face each other. 5. The method according to claim 3, wherein in the bonding step, the two element units are bonded via an adhesive. 6. The step of forming the element unit, the step of forming the solar cell element film on a semiconductor substrate;
Forming an electrode layer on the surface of the solar cell element film, bonding the support substrate to the surface of the solar cell element film, and separating the semiconductor substrate from the solar cell element film. The method for manufacturing a solar cell according to claim 2, wherein: 7. A step of forming a porous layer by anodization near the surface of the semiconductor substrate on which the solar cell element film is formed before forming the solar cell element film on the semiconductor substrate. 7. The method for manufacturing a solar cell according to claim 6, comprising: 8. The method according to claim 6, wherein the semiconductor substrate is formed of Si (silicon) or Ge (germanium). 9. The method according to claim 6, wherein the solar cell element film is formed on the semiconductor substrate by epitaxial growth or heteroepitaxial growth. 10. The step of forming the element unit, the step of forming the solar cell element film on a semiconductor substrate, the step of forming an electrode layer on the surface of the solar cell element film, and the step of forming the solar cell element film Bonding a support member to the surface of the solar cell element, separating the semiconductor substrate from the solar cell element film, and bonding the support substrate to the surface of the solar cell element film from which the semiconductor substrate has been separated. 3. The method of manufacturing a solar cell according to claim 2, further comprising: a step of peeling the support member from the solar cell element film. 11. A step of forming a porous layer by anodization near the surface of the semiconductor substrate on which the solar cell element film is formed before forming the solar cell element film on the semiconductor substrate. The method for manufacturing a solar cell according to claim 10, further comprising: 12. The supporting substrate is formed of a semiconductor substrate. The step of forming the element unit includes the step of forming the solar cell element film on the semiconductor substrate. After the step of bonding the element unit, The method according to claim 2, wherein the semiconductor substrate is separated from the solar cell element film. 13. A step of forming a reflection surface having minute irregularities on a surface of the solar cell element film from which the semiconductor substrate has been separated, following the step of separating the semiconductor substrate from the solar cell element film. The method for manufacturing a solar cell according to claim 12, comprising: 14. A step of forming a porous layer by anodization near the surface of the semiconductor substrate on which the solar cell element film is formed before forming the solar cell element film on the semiconductor substrate. 14. The method for manufacturing a solar cell according to claim 13, comprising: 15. A method for manufacturing a solar cell comprising a plurality of solar cell element films arranged two-dimensionally, comprising: forming an element unit in which the solar cell element films are supported by a support substrate; Bonding the element unit to a common surface of a common member. 16. The method for manufacturing a solar cell according to claim 15, further comprising a step of peeling said support substrate from solar cell element films of said plurality of element units adhered to said common member. 17. The step of forming the element unit, comprising a step of forming a plus electrode and a minus electrode on a surface of each of the solar cell element films to be bonded to the common member. Item 16. The method for manufacturing a solar cell according to Item 15. 18. The method according to claim 18, wherein, in the step of bonding the element unit to the common member, a positive electrode of each solar cell element film is connected to a negative electrode of an adjacent solar cell element film. The method for manufacturing a solar cell according to claim 17, wherein the films are connected in series. 19. The manufacturing of a solar cell according to claim 15, wherein said supporting substrate is made of a semiconductor substrate, and said solar cell element film is formed on said semiconductor substrate by epitaxial growth or heteroepitaxial growth. Method.