JPH1140832A - Thin-film solar cell and manufacture therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin-film solar cell which is lessened in manufacturing cost while maintaining high conversion efficiency and capable of saving resources and a manufacturing method thereof. SOLUTION: Irregularities are provided to the surface of a p-type single crystal silicon board 1. H ions are implanted in layers into the irregular surface of the p-type single crystal silicon board 1 as deep as 5 to 10 μm. A lower electrode layer 6 is formed on a substrate 4 via the intermediary of an insulating layer 5. The irregular surface of the p-type single-crystal board 1 is bonded to the surface of the lower electrode layer 6. By a heat treatment, the p-type single-crystal silicon board 1 is cut into a rugged single-crystal silicon layer 1a which is bonded onto the lower electrode layer 6 and a residual p-type single- crystal board 1b along a gap region 3a distributed in a layer. Through the heat treatment, n-type impurities are diffused into the p-type single-crystal silicon layer 1a from the lower electrode layer 6 so as to form an n-type diffusion layer 1c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a crystalline thin-film solar cell and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a crystalline solar cell made of crystalline silicon such as monocrystalline silicon and polycrystalline silicon, it has been proposed to form an uneven shape on the surface of crystalline silicon in order to reduce the surface reflectance. .

[0003] In the production of such a crystalline solar cell, a polycrystalline or single-crystal silicon ingot (bulk crystal) produced by a pulling method or a casting method is cut into a thin wafer, and the surface of the wafer is machined. An uneven shape is formed by mechanical scribing or chemical etching. Then, a pn junction is formed on the surface of the concavo-convex shape formed on the wafer by a diffusion method or an ion implantation method, and further, an electrode is formed by a vacuum evaporation method, a printing firing method, or a plating method.

[0004]

In the above-mentioned crystalline solar cell, the surface reflection of incident light can be reduced due to the unevenness formed on the surface. Thereby, the conversion efficiency can be improved.

According to the conventional manufacturing method, it is difficult to form irregularities on both the front surface and the back surface of the solar cell. As a result, the back surface of the solar cell is flat, so that it cannot be said that light that has entered the inside of the solar cell is sufficiently confined. Therefore, for example, Applied Physics Letters, Vol. 70, pp. 390-392 (Ap.
As described in plied Physics Letters, 70 (3), (1997) 390-392), by realizing a structure with unevenness on the front and back surfaces of the solar cell, light confined inside the solar cell can be confined. Attempts have been made to further improve the conversion efficiency by performing it sufficiently. However, the structure in which the unevenness is formed on the front and back surfaces of the solar cell has been realized only by depositing a polycrystalline thin film on the uneven substrate as described in the above-mentioned literature. Was difficult, and excellent properties were not obtained.

Further, in the conventional method of manufacturing a crystalline solar cell, a cutting margin occurs when a wafer is cut from a single crystal silicon or polycrystalline silicon silicon ingot. For example, when a wafer having a thickness of several hundreds of μm is cut out from a silicon ingot having a diameter of 15 cm or a square of 15 cm, a cutting margin having a thickness similar to that of the wafer, that is, a thickness of several hundreds of μm is generated. Therefore, waste of silicon having the same thickness as the silicon wafer actually used occurs.

[0007] Further, in a crystalline solar cell, the thickness contributing to photoelectric conversion is not more than 100 µm, but it is difficult to cut a silicon ingot into a wafer having a thickness of not more than 100 µm. For this reason, in the conventional crystalline solar cell, silicon having an unnecessarily thick thickness is used, which causes waste.

In particular, since single crystal silicon is expensive,
Solar cells using polycrystalline silicon, which has inferior characteristics to single crystal silicon, are mainly manufactured.

It is an object of the present invention to provide a thin-film solar cell capable of reducing costs and saving resources while securing high conversion efficiency, and a method for manufacturing the same.

[0010]

According to a first aspect of the present invention, there is provided a method of manufacturing a thin-film solar cell, comprising: a first step of forming an uneven shape on a surface of a crystalline semiconductor; A second step of ion-implanting a predetermined element in a layer at a predetermined depth from a third step, a third step of forming an electrode layer on the substrate, and a step of forming an uneven surface of the crystal semiconductor into which the predetermined element has been implanted. A fourth step of adhering to the surface of the electrode layer formed on the substrate, and a heat treatment to form voids distributed in a layered manner in the region of the predetermined element injected into the crystal semiconductor, thereby distributing the crystal semiconductor in a layered manner. A fifth step of cutting into an uneven crystal semiconductor layer adhered on the electrode layer by cutting in the region of the formed gap and separating the remaining crystal semiconductor from the uneven crystal semiconductor layer adhered on the electrode layer; 6th forming power generation layer
And the steps of

In the method for manufacturing a thin-film solar cell according to the present invention, first, in a first step, an uneven shape is formed on the surface of the crystalline semiconductor, and in a second step, a predetermined shape is formed from the uneven surface of the crystalline semiconductor. In a third step, a predetermined element is ion-implanted in a layer at a depth, an electrode layer is formed on the substrate in a third step, and in a fourth step, the uneven surface of the crystal semiconductor into which the predetermined element has been implanted is removed. It adheres to the surface of the electrode layer formed on the substrate. Then, in the fifth step, the predetermined element is moved to a dangling bond of a constituent element in a crystal defect formed by ion implantation into the crystalline semiconductor by heat treatment, and the element is bonded to the dangling bond. Terminate the dangling bond. Accordingly, voids distributed in a layered manner are formed in the crystal semiconductor, and the crystalline semiconductor is divided in regions of the voids distributed in the layered shape. As a result, a crystal semiconductor layer having an uneven shape bonded to the electrode layer and the remaining crystal semiconductor are obtained.

If the amount of ion implantation is insufficient, the transferred implanted elements form voids and do not form voids necessary for division, which is inappropriate. On the other hand, if the implantation energy is too low, the divided layer is also broken in the longitudinal direction, and the divided layers are not integrated, which is inappropriate.

Further, in a sixth step, a power generation layer is formed on the uneven crystalline semiconductor layer adhered on the electrode layer. In this way, a solar cell having a power generation layer having an uneven shape is manufactured.

Since the thickness of the power generation layer substantially corresponds to the implantation depth of the predetermined element, a power generation layer made of a crystalline semiconductor having an arbitrary thickness can be formed by adjusting the implantation depth. Therefore, the power generation layer can be easily formed to a thin thickness required for photoelectric conversion.

In the thin-film solar cell manufactured by the manufacturing method according to the present invention, the front surface and the back surface of the power generation layer are formed in an uneven shape. Therefore, the reflection of the incident light on the surface of the power generation layer is reduced, and the amount of light entering the inside of the power generation layer increases. In addition, since the probability of incident light being obliquely refracted into the power generation layer increases due to the unevenness of the surface, the distance that light travels inside the power generation layer becomes longer. Thereby, light is effectively used for photoelectric conversion. Furthermore, the probability that the light traveling inside the power generation layer is totally reflected by the irregularities on the back surface increases, so that the light is confined favorably. As a result, the conversion efficiency is further improved.

In addition, since the power generation layer formed of the crystal semiconductor layer having the uneven shape is formed to have a small thickness, the crystal semiconductor is not wasted. Therefore, cost reduction and resource saving can be achieved while securing high conversion efficiency.

In particular, the electrode layer on the substrate may double as the adhesive. This facilitates the bonding of the crystalline semiconductor in the fourth step.

The first conductivity type crystal semiconductor may be used as the crystal semiconductor, and the second conductivity type crystal semiconductor layer may be formed in or on the uneven crystal semiconductor layer in the sixth step. Thereby, a power generation layer is formed.

Further, a first conductivity type crystal semiconductor is used as a crystal semiconductor, a second conductivity type impurity element (second conductivity type dopant) is added to the electrode layer in a third step, and a heat treatment is performed in a sixth step. The impurity element may be diffused from the electrode layer into the uneven crystalline semiconductor layer. In this case, the formation of the power generation layer is facilitated.

Further, the crystalline semiconductor may be crystalline silicon. In this case, single crystal silicon is preferably used as crystalline silicon. Alternatively, polycrystalline silicon may be used as crystalline silicon.

In the first step, it is preferable that the above-mentioned predetermined element is ion-implanted in layers in a depth of 5 μm or more and 10 μm or less from the uneven surface of the crystal semiconductor. Thus, a crystalline semiconductor layer having a concavo-convex shape with a thickness of 5 μm or more and 10 μm or less can be formed. In this case, a power generating layer having a small thickness necessary for photoelectric conversion is formed.

Further, the remaining crystalline semiconductor separated in the fifth step may be reused in the second step. This makes it possible to reduce waste of the crystalline semiconductor.

A thin-film solar cell according to a second aspect of the present invention includes a substrate, an electrode layer formed on the substrate, and a power generation layer formed on the electrode layer and formed of an uneven crystalline semiconductor layer. is there.

In the thin-film solar cell according to the present invention, the front surface and the back surface of the power generation layer are formed in an uneven shape. Therefore, the reflection of the incident light on the surface of the power generation layer is reduced, and the amount of light entering the inside of the power generation layer increases. In addition, since the probability of incident light being obliquely refracted into the power generation layer increases due to the unevenness of the surface, the distance that light travels inside the power generation layer becomes longer. Thereby, light is effectively used for photoelectric conversion. Furthermore, the probability that the light traveling inside the power generation layer is totally reflected by the irregularities on the back surface increases, so that the light is confined favorably. As a result, the conversion efficiency is further improved.

[0025]

1 to 5 are schematic process diagrams showing a method for manufacturing a thin-film solar cell according to one embodiment of the present invention.

As shown in FIG. 1A, the specific resistance is 10Ω.
A p-type single crystal silicon plate 1 of about cm is used. First, as shown in FIG. 1B, an uneven shape 2 is formed on the surface of a p-type single crystal silicon plate 1 by mechanical scribe or chemical etching. In this embodiment, in order to simplify the manufacturing process, a linear pattern composed of a plurality of V-shaped grooves is formed as the concavo-convex shape 2 by mechanical scribing (cutting). The inclination angle θ of the inner surface of the V-shaped groove is, for example, 60 °,
The width D of the V-shaped groove is, for example, about 10 μm.

Next, as shown in FIG. 1C, H (hydrogen) ions are implanted into the p-type single crystal silicon plate 1. As a result, an implanted region of atomic hydrogen 3 is formed at a predetermined depth from the surface of uneven shape 2 of p-type single crystal silicon plate 1. The conditions for the ion implantation are as follows: the acceleration energy of hydrogen ions (H ⁺ ) is 500 keV, and the dose is 5 × 10 ¹⁶ /
cm ² to 1 × 10 ¹⁷ / cm ² . As a result, the depth of the implantation region of the atomic hydrogen 3 is set to about 1
0 μm.

Next, as shown in FIG. 2D, an insulating layer 5 made of amorphous SiO ₂ , Al ₂ O ₃ or the like is formed on a substrate 4 made of a heat-resistant glass plate or a metal sheet such as stainless steel or copper. Is formed by a sputtering method, a printing method (printing method), or the like, and an electrode forming paste 6 a is applied on the insulating layer 5. This electrode forming paste 6a is made of Ag (silver),
Metal particles such as Cu (copper) and Al (aluminum) are dispersed in an organic solvent, and P (phosphorus) particles, which are n-type impurities (n-type dopants), are added.

Then, as shown in FIG. 2E, the surface of the irregular shape 2 of the p-type single crystal silicon plate 1 is attached to the surface of the electrode forming paste 6a, and heat treatment is performed at 300 to 500 ° C. The organic solvent in the paste 6a is evaporated. Thereby, the lower electrode layer 6 made of a metal such as Ag, Cu, or Al is formed, and the p-type single-crystal silicon plate 1 is bonded to the lower electrode layer 6. That is, FIG.
The electrode forming paste 6a of (d) also serves as a material of the lower electrode layer 6 and an adhesive.

Thereafter, as shown in FIG.
Heat treatment at ~ 700 ° C. Thereby, atomic hydrogen 3
Move to the dangling bond of the constituent element in the crystal defect formed by the ion implantation, and bond with the dangling bond to terminate the dangling bond. As a result, a large number of voids distributed in a layered manner at a depth of about 10 μm from the surface of the uneven shape 2 of the p-type single-crystal silicon plate 1 are formed. Area 3a
Is divided.

Thus, a p-type single-crystal silicon layer 1a having a thickness of about 10 μm and a remaining p-type single-crystal silicon plate 1b adhered on the lower electrode layer 6 are obtained. In this case, both the front surface and the back surface of the p-type single crystal silicon layer 1a have irregularities. p-type single-crystal silicon layers 1a and p
The fine irregularities on the surface of the irregular shape of the mold single crystal silicon plate 1b are several tens nm or less.

Next, as shown in FIG.
Heat treatment is performed at 900 ° C. Thereby, the adhesion between the lower electrode layer 6 and the p-type single crystal silicon layer 1a having the uneven shape is strengthened, and the n-type impurity diffuses from the lower electrode layer 6 into the p-type single crystal silicon layer 1a, and the n-type impurity is diffused. The diffusion layer 1c is formed. As a result, a power generation layer A composed of a pn junction between the p-type single crystal silicon layer 1a and the n-type diffusion layer 1c is formed.

In the above example, the power generation layer A is formed by diffusing the n-type impurity from the electrode layer. However, after the first step of forming the irregularities on the crystal surface, ion implantation or thermal diffusion from the surface is performed. The power generation layer A is also formed by introducing an n-type impurity by the above method.

Further, as shown in FIG. 4 (h), fine irregularities (damaged areas) on the irregular surface of the p-type single crystal silicon layer 1a and the irregular surface of the divided p-type single crystal silicon plate 1b are obtained. ) Is polished by chemical etching. The polished p-type single crystal silicon plate 1b can be reused in the step of FIG. 1 (c).

Next, as shown in FIG. 4 (i), the p-type single crystal silicon layer 1a is
A mixture of Si, N, O, or Ti, Al
A passivation film 7 is formed by depositing a dielectric material including a single layer or a laminated structure. This passivation film 7 also serves as a protective film and an antireflection film.

Finally, as shown in FIG. 5J, a predetermined region of the passivation film 7 is removed by patterning to deposit an electrode material, or an electrode material is provided in a predetermined region of the passivation film 7 and heat treatment is performed. Depending on the process
The upper electrode 8 is formed on the p-type single crystal silicon layer 1a by making contact with the mold substrate. As a method for forming the upper electrode 8, a paste in which metal particles such as Ag, Cu, and Al are dispersed in an organic solvent is applied and baked at about 400 ° C. When a direct electrode material is provided, it is possible to form a direct electrode via the passivation film 7 by baking at 700 ° C. for a short time. Thus, a solar cell made of single-crystal silicon is manufactured.

FIGS. 6 and 7 are schematic process sectional views showing a method of manufacturing a thin-film solar cell according to another embodiment of the present invention.

FIG. 6A shows a p-type single crystal silicon plate 1 of 0.5 Ω · cm. First, as shown in FIG.
A desired mask pattern is formed on the (100) surface of the p-type single-crystal silicon plate 1 (not shown), and is etched by a known anisotropic etching method to form a concavo-convex shape 2 having a flat portion in part. . When the mask opening is square, the concave portion of the concavo-convex shape 2 to be formed becomes an inverted pyramid pit, and the inclination angle θ of the inner surface thereof is about 55 °. Since this angle is determined crystallographically, it is uniform over the entire surface of the silicon plate 1. The side length D of the inverted pyramid-shaped concave portion of the concave-convex shape 2 is, for example, 5 μm. In addition, the width of the flat portion is 20 μm to 50 μm.

Next, as shown in FIG. 6C, an n-type impurity such as phosphorus is introduced into a part of the flat portion by thermal diffusion or ion implantation to form an n-type region 1e. A p-type impurity such as boron is introduced into the other part of the flat portion by thermal diffusion or ion implantation to form a p-type region 1d. For this formation, a known mask film such as an oxide film and the formation of an opening, impurity introduction and heat treatment are applied. The depth of each of the regions 1e and 1d is about 1 μm. The formation of the p-type region 1d is not essential, and may be omitted when the specific resistance of the p-type single crystal silicon plate 1 is small as in this embodiment. It is desirable that a thin oxide film of about 0.1 μm be formed on the surface of the silicon plate 1.

Next, as shown in FIG. 6D, hydrogen (H) ions are implanted into the entire surface of the p-type single crystal silicon plate 1 having the impurity regions formed on the surface. The conditions for the ion implantation are as follows: the acceleration energy of hydrogen ions (H ⁺ ) is 1 MeV
And the dose is 1 × 10 ¹⁷ / cm ² to 2 × 10 ¹⁷ / c
and m ^2. Thereby, the depth of the implantation region of atomic hydrogen 3 is about 10 μm from the surface of p-type single crystal silicon plate 1. The implantation region of the atomic hydrogen 3 has a shape obtained by translating the surface shape of the silicon plate 1 by about 10 μm in the depth direction. The implanted hydrogen ions pass through the surface region of the silicon plate 1 with almost no effect on the surface diffusion region, and form high-concentration crystal defects only in a region having a small static depth.

Next, a wiring board is prepared for peeling and holding the thin film. FIG. 7E shows an insulating layer 5 such as a high-purity glass film or an alumina film formed on a surface of a substrate 4 such as a heat-resistant glass plate, a ceramic or a metal sheet such as stainless steel.
The electrode wirings 6b and 6c are further formed on a wiring substrate formed and fired by a method D, a sputtering method, a coating method, a printing method, or the like. The electrode wiring 6c is an n-type region 1e of the silicon plate 1.
The electrode wiring 6b is made of a metal paste containing Ag as a main component to make contact with the p-type region 1 of the silicon plate 1.
Ag paste containing Al to make contact with d. These are formed in desired regions of other wirings (not shown) for conducting electric output from the contacts, respectively, and are formed on a flat portion of the silicon plate 1 so as to be compatible with the bonding process described below. It is provided to face region 1e and p-type region 1d.

The wiring board and the hydrogen-implanted silicon plate 1 shown in FIG. 6D face each other as shown in FIG. 7F, and an n-type region 1 formed on the surface of the silicon plate 1 is formed.
e and the electrode wiring (Ag paste formation portion) 6c formed on the wiring board, and the p formed on the surface of the silicon plate 1
The electrode wiring (Ag (A
1) Paste forming portion) 6b is pressed against each other while facing each other, and in this state, heat treatment is performed at 700 ° C. for 5 minutes.
Even if there is a thin oxide film, each of the electrode wirings 6c and 6d forms a good ohmic contact with the n-type region 1e and the p-type region 1d via the thin oxide film. When the silicon plate 1 to be bonded is large, it cannot be prevented that contacts are formed on the n-type region 1e and the p-type region 1d of the silicon plate 1 in advance. This step may be performed before or after hydrogen ion implantation.

In the heat treatment step, as shown in FIG. 7 (g), adhesion at the contact portion and separation due to the growth of the voids generated in the region where the atomic hydrogen 3 is implanted are simultaneously achieved. The layer 1a is peeled off in a state of being adhered to the wiring substrate, and the p-type single crystal silicon plate 1b remains. The silicon plate 1b from which the p-type single crystal silicon layer 1a has been removed
The surface shape is almost the same as that of the silicon plate 1 after the etching shown in FIG. 6B, and the fine irregularities on the surface are removed by etching and reused in the steps shown in FIG.

The fine irregularities on the peeled surface of the peeled p-type single crystal silicon layer 1a are lightly etched, and the surface thereof is further coated with an antireflection film 7 by a CVD method as shown in FIG.
It is formed by a plasma CVD method or the like. The antireflection film 7 is preferably a silicon oxide film, a nitride film, a Ti oxide film, or the like, and the thickness thereof is appropriately set to 0.06 μm to 0.11 μm depending on the refractive index of the material so as to satisfy the antireflection condition. Choose the thickness. Thus, the p-type single crystal silicon layer 1a and the n-type region 1
e, a power generation layer A consisting of a pn junction with e is formed.
A solar cell having a structure in which current collecting electrodes are integrated on the back surface is completed.

In the solar cells of these examples, p
The power generation layer A composed of the single-crystal silicon layer 1a and the n-type diffusion layer 1c (or the n-type region 1e) has both a front surface and a rear surface formed in an uneven shape. Thereby, the reflection of the incident light on the surface of the power generation layer A is reduced, and the amount of light entering the inside of the power generation layer A increases. In addition, the probability that incident light is obliquely refracted into the power generation layer A due to the unevenness of the surface increases, so that the distance that light travels inside the power generation layer A increases.
Thereby, light is effectively used for photoelectric conversion. Further, the probability that the light traveling inside the power generation layer A is totally reflected by the irregularities on the back surface increases, so that the light is confined favorably. As a result, the conversion efficiency is further improved.

Further, according to the manufacturing method of the present embodiment, the power generation layer A can be formed as thin as about 5 μm to about 10 μm, so that the amount of single crystal silicon used can be reduced while ensuring high conversion efficiency. It is possible to save resources and reduce costs.

In the above embodiment, a single crystal silicon plate is used as a crystal semiconductor, but a single crystal silicon ingot, a polycrystal silicon plate, a polycrystal silicon ingot, or another crystal semiconductor is used instead of the single crystal silicon plate. May be used.

Further, in the above embodiment, H is ion-implanted into the single crystal silicon plate 1 in the step of FIG. 1C in order to divide the single crystal silicon plate 1 in the step of FIG. However, halogen elements such as fluorine, chlorine, bromine and iodine can be used instead of H.

Further, in the above embodiment, a linear pattern composed of a plurality of V-shaped grooves is formed as the concave-convex shape 2 in the step of FIG. A pattern may be formed, or a fine pyramid-shaped intersection pattern may be formed by chemical etching using an alkaline aqueous solution.

In the solar cell of the above embodiment, the conductivity type of each layer may be reversed.

[Brief description of the drawings]

FIG. 1 is a schematic process sectional view showing a method for manufacturing a thin-film solar cell according to one embodiment of the present invention.

FIG. 2 is a schematic process sectional view showing a method for manufacturing a thin-film solar cell according to one embodiment of the present invention.

FIG. 3 is a schematic process sectional view showing a method for manufacturing a thin-film solar cell according to one embodiment of the present invention.

FIG. 4 is a schematic process sectional view showing a method for manufacturing a thin-film solar cell according to one embodiment of the present invention.

FIG. 5 is a schematic process sectional view showing a method for manufacturing a thin-film solar cell according to one embodiment of the present invention.

FIG. 6 is a schematic process sectional view showing a method for manufacturing a thin-film solar cell according to another embodiment of the present invention.

FIG. 7 is a schematic process sectional view showing a method for manufacturing a thin-film solar cell according to another embodiment of the present invention.

[Explanation of symbols]

 1, 1b p-type single crystal silicon plate 1c n-type diffusion layer 1e n-type region 2 uneven shape 3 atomic hydrogen 3a void region 4 substrate 5 insulating layer 6 lower electrode layer 6b electrode wiring 6c electrode wiring 8 upper electrode layer A power generation layer

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Mitsunori Warakosako 1-280 Higashi Koigabo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd.

Claims (8)

[Claims] A first step of forming a concavo-convex shape on the surface of the crystal semiconductor; and a second step of ion-implanting a predetermined element in a layer from the surface of the concavo-convex shape of the crystal semiconductor to a predetermined depth. A third step of forming an electrode layer on a substrate, and a fourth step of bonding the surface of the concave-convex shape of the crystal semiconductor into which the predetermined element has been implanted to the surface of the electrode layer formed on the substrate. Forming a gap distributed in a layered manner in the region of the predetermined element injected into the crystal semiconductor by heat treatment, and cutting the crystal semiconductor in the region of the gap distributed in the layered shape to form a gap on the electrode layer. A fifth step of separating the concave-convex-shaped crystal semiconductor layer and the remaining crystal semiconductor adhered to the substrate, and a sixth step of forming a power generation layer on the concave-convex-shaped crystal semiconductor layer adhered on the electrode layer And a thin film comprising: Method of manufacturing a solar cell. 2. The method according to claim 1, wherein the electrode layer on the substrate also serves as an adhesive. 3. The method according to claim 1, wherein a first conductivity type crystal semiconductor is used as the crystal semiconductor, and a second conductivity type crystal semiconductor layer is formed in the uneven semiconductor crystal layer or on the uneven crystal semiconductor layer in the sixth step. The method for manufacturing a thin-film solar cell according to claim 1, wherein the thin-film solar cell is formed. 4. A first conductivity type crystal semiconductor is used as said crystal semiconductor, a second conductivity type impurity element is added to said electrode layer in said third step, and said electrode layer is heat-treated in said sixth step. 4. The method for manufacturing a thin-film solar cell according to claim 1, wherein the impurity element is diffused into the uneven crystalline semiconductor layer. 5. The method according to claim 1, wherein the crystalline semiconductor is crystalline silicon. 6. The method according to claim 1, wherein in the first step, the predetermined element is not less than 5 μm and not more than 10 μm from a surface of the irregular shape of the crystal semiconductor.
The method for producing a thin-film solar cell according to any one of claims 1 to 5, wherein ions are implanted in a layer to a depth of not more than m. 7. The thin-film solar cell according to claim 1, wherein the remaining crystalline semiconductor separated in the fifth step is reused in the second step. Method. 8. A thin-film solar cell comprising: a substrate; an electrode layer formed on the substrate; and a power generation layer formed on the electrode layer and formed of a crystalline semiconductor layer having an uneven shape.