阅读说明：本技术 太阳能单电池和太阳能单电池的制造方法 (Solar cell and method for manufacturing solar cell ) 是由 兼松大二 益子庆一郎 中井出 片山博贵 于 2019-01-09 设计创作，主要内容包括：太阳能单电池(1)包括：具有受光面(10a)和背面(10b)的半导体基片(10)；在半导体基片(10)的背面(10b)上在第一方向延伸且在与第一方向交叉的第二方向上彼此相邻设置的n型半导体层(13n)和p型半导体层(12p)；和设置在n型半导体层(13n)和p型半导体层(12p)上的基底层(14)。基底层(14)包括：通过具有第一分离部(17a)和第二分离部(17b)的第一分离槽(17)被彼此分离的n侧基底层(14n)和p侧基底层(14p)；和将第一分离部(17a)和第二分离部(17b)分隔开的第一桥部(18)。第一桥部(18)在n侧基底层(14n)和p侧基底层(14p)的在第一方向上的边界中的至少一处,将第一分离部(17a)和第二分离部(17b)分隔开。(A solar cell (1) is provided with: a semiconductor substrate (10) having a light-receiving surface (10a) and a back surface (10 b); an n-type semiconductor layer (13n) and a p-type semiconductor layer (12p) extending in a first direction on a back surface (10b) of the semiconductor substrate (10) and disposed adjacent to each other in a second direction intersecting the first direction; and a base layer (14) provided on the n-type semiconductor layer (13n) and the p-type semiconductor layer (12 p). The base layer (14) comprises: an n-side base layer (14n) and a p-side base layer (14p) separated from each other by a first separation groove (17) having a first separation portion (17a) and a second separation portion (17 b); and a first bridge part (18) that separates the first separation part (17a) and the second separation part (17 b). The first bridge part (18) separates the first separation part (17a) and the second separation part (17b) at least one of boundaries in the first direction of the n-side base layer (14n) and the p-side base layer (14 p).)

1. A back junction solar cell, comprising:

a semiconductor substrate having a light receiving surface on which light is incident and a back surface facing away from the light receiving surface;

an n-type semiconductor layer and a p-type semiconductor layer extending in a first direction and disposed adjacent to each other in a second direction intersecting the first direction on the back surface of the semiconductor substrate; and

a base layer disposed on the n-type semiconductor layer and the p-type semiconductor layer,

the base layer includes: an n-side base layer disposed on the n-type semiconductor layer and a p-side base layer disposed on the p-type semiconductor layer, separated from each other by a first separation groove having a first separation portion and a second separation portion extending in different directions; and a first bridge portion separating the first and second separated portions,

the n-side base layer has a first n-side base portion extending in the first direction,

the p-side base layer has a first p-side base portion extending in the first direction and disposed adjacent to the first n-side base portion,

the first bridge portion separates the first separation portion and the second separation portion at least one of a boundary between a first end portion of the first n-side group base portion in one side in the first direction and the p-side group base layer and a boundary between a second end portion of the first p-side group base portion in the other side in the first direction and the n-side group base layer.

2. The solar cell as claimed in claim 1, wherein:

the n-side group base layer has a second n-side group base extending in the second direction and connecting the other side end of the first n-side group base in the first direction,

the p-side base layer has a second p-side base portion extending in the second direction and connecting a side end portion in the first direction of the first p-side base portion,

the first separation portion extends in the first direction and is provided between the first n-side group base portion and the first p-side group base portion that are adjacent to each other in a plan view of the solar cell,

the second separation portions are respectively disposed between the first end portion and the second p-side group base portion and between the second end portion and the second n-side group base portion,

the length of the second separated portion in the second direction is greater than the interval between the first separated portions adjacent to each other,

the first bridge portion separates an end portion of the first separated portion in the first direction from the second separated portion.

3. The solar cell as claimed in claim 2, wherein:

the length of the first bridge in the first direction is equal to or less than the length of the first bridge in the second direction.

4. The solar cell as claimed in claim 1, wherein:

the n-side base layer has a second n-side base portion extending in a second direction intersecting the first direction and connecting the other side end portion in the first direction of the first n-side base portion,

the p-side base layer has a second p-side base portion extending in the second direction and connecting a side end portion in the first direction of the first p-side base portion,

one end of the first separation portion is provided at a boundary between the first p-side base portion and the second n-side base portion, and the other end is provided at a boundary between one of the first n-side base portion and the second p-side base portion adjacent to the first p-side base portion in a plan view of the solar cell,

one end portion of the second separating portion is provided at a boundary between the first p-side base portion and the second n-side base portion, and the other end portion is provided at a boundary between the other first n-side base portion adjacent to the first p-side base portion and the second p-side base portion in a plan view of the solar cell,

the first bridge portion separates adjacent end portions of the first and second separated portions.

5. The solar cell as claimed in any one of claims 1 to 4, further comprising:

a conductive layer disposed on the n-side base layer and the p-side base layer,

the conductive layer includes: an n-side conductive layer provided on the n-side base layer and a p-side conductive layer provided on the p-side base layer, which are separated from each other by a second separation groove, and a second bridge portion provided on the first bridge portion and separating the second separation groove.

6. The solar cell as claimed in claim 5, further comprising:

an n-side electrode formed of a plated film and provided on the n-side conductive layer; and

a p-side electrode formed of a plating film and provided on the p-side conductive layer,

the first separation groove is disposed between the n-side electrode and the p-side electrode and at a position close to the n-side electrode or the p-side electrode when the solar cell is viewed in a plan view.

7. Solar cell as claimed in any one of claims 1 to 6, characterized in that:

the base layer is composed of a transparent material.

8. A method for manufacturing a back junction solar cell, comprising the steps of:

a semiconductor layer forming step of forming an n-type semiconductor layer and a p-type semiconductor layer extending in a first direction and provided adjacent to each other in a second direction intersecting with the first direction on a back surface of a semiconductor substrate having a light receiving surface on which light is incident and a back surface facing away from the light receiving surface;

a base layer forming step of forming a base layer on the back surface on which the n-type semiconductor layer and the p-type semiconductor layer are formed;

a conductive layer forming step of forming a conductive layer on the base layer;

a resist forming step of applying a resist on the conductive layer and in a region corresponding to the n-type semiconductor layer and the p-type semiconductor layer;

an electrode forming step of forming an n-side electrode and a p-side electrode by electrolytic plating using the conductive layer on which the resist film is formed in the resist forming step as a seed layer;

a laser processing step of forming a groove penetrating to the seed layer on the resist film by scanning with a laser after the electrode forming step;

a base layer removing step of etching the back surface on which the groove is formed to form a separation groove for separating the base layer into an n-side base layer and a p-side base layer; and

a resist removing step of removing the resist film after the base layer removing step,

in the laser processing step, the separation groove that separates the first separation portion and the second separation portion extending in different directions is formed at a position where a scanning path scanned by the laser beam intersects, by stopping the output of the laser beam.

9. The method for manufacturing a solar cell according to claim 8, wherein:

in the laser processing step, when the solar cell is cut out, a laser beam is scanned between a position where the thickness of the resist film is the largest and the n-side electrode or the p-side electrode.

10. The method for manufacturing a solar cell according to claim 8, wherein:

in the laser processing step, when the solar cell is sectioned, a laser beam is scanned at a position close to the n-side electrode or the p-side electrode.

Technical Field

The present invention relates to a back junction type solar cell and a method for manufacturing the solar cell.

Background

As a solar cell having improved photoelectric conversion efficiency, a back junction type solar cell has been studied, in which both an n-type semiconductor layer and a p-type semiconductor layer are formed on a back surface opposite to a light receiving surface on which light is incident on a semiconductor substrate. In a back junction type solar cell, a transparent electrode layer (base layer), a seed layer (conductive layer), and plating layers (an n-side electrode and a p-side electrode) for extracting generated power are stacked on a back surface.

Patent document 1 discloses a solar cell in which an n-side electrode and a p-side electrode are completely separated by a separation region (separation groove) provided in a transparent electrode layer.

Disclosure of Invention

Problems to be solved by the invention

As a method of forming the separation grooves in the base layer, laser processing may be performed. As described above, when the base layer is completely separated by the separation grooves, in the patterning by the laser, a portion where the scanning paths cross each other is generated. If the laser light is irradiated during scanning of the laser light on the scanning path, a portion over-irradiated with the laser light is generated. Thus, the semiconductor layer and the semiconductor substrate may be damaged, and the photoelectric conversion efficiency may be lowered.

Accordingly, an object of the present invention is to provide a solar cell and a method of manufacturing the solar cell, which can suppress damage to a semiconductor layer or the like when laser processing is performed.

Means for solving the problems

In order to achieve the above object, a solar cell according to an aspect of the present invention is a back junction type solar cell including: a semiconductor substrate having a light receiving surface on which light is incident and a back surface facing away from the light receiving surface; an n-type semiconductor layer and a p-type semiconductor layer extending in a first direction and provided adjacent to each other in a second direction intersecting the first direction on the back surface of the semiconductor substrate; and a base layer provided on the n-type semiconductor layer and the p-type semiconductor layer, the base layer including: an n-side base layer provided on the n-type semiconductor layer and a p-side base layer provided on the p-type semiconductor layer, which are separated from each other by a first separation groove having a first separation portion and a second separation portion extending in different directions; and a first bridge portion that separates the first separation portion and the second separation portion, wherein the n-based foundation layer has a first n-based foundation portion extending in the first direction, the p-based foundation layer has a first p-based foundation portion extending in the first direction and disposed adjacent to the first n-based foundation portion, and the first bridge portion separates the first separation portion and the second separation portion at least one of a boundary between a first end portion of the first n-based foundation portion on one side in the first direction and the p-based foundation layer, and a boundary between a second end portion of the first p-based foundation portion on the other side in the first direction and the n-based foundation layer.

Further, a method for manufacturing a solar cell according to an aspect of the present invention is a method for manufacturing a back junction type solar cell, including the steps of: a semiconductor layer forming step of forming an n-type semiconductor layer and a p-type semiconductor layer extending in a first direction and provided adjacent to each other in a second direction intersecting with the first direction on a back surface of a semiconductor substrate having a light receiving surface on which light is incident and a back surface facing away from the light receiving surface; a base layer forming step of forming a base layer on the back surface on which the n-type semiconductor layer and the p-type semiconductor layer are formed; a conductive layer forming step of forming a conductive layer on the base layer; a resist forming step of applying a resist to a region corresponding to the n-type semiconductor layer and the p-type semiconductor layer on the conductive layer; an electrode forming step of forming an n-side electrode and a p-side electrode by electrolytic plating using the conductive layer on which the resist film is formed in the resist forming step as a seed layer; a laser processing step of forming a groove penetrating the seed layer on the resist film by scanning with a laser after the electrode forming step; a base layer removing step of etching the back surface on which the groove is formed to form a separation groove for separating the base layer into an n-side base layer and a p-side base layer; and a resist removing step of removing the resist film after the base layer removing step, wherein in the laser processing step, the laser beam is stopped from being output at a position where a scanning path scanned by the laser beam intersects, thereby forming the separation groove at the position, the separation groove separating the first separation portion and the second separation portion extending in different directions.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to realize a solar cell which can suppress damage to a semiconductor layer or the like when processed by laser light, and a method for manufacturing the same.

Drawings

Fig. 1 is a plan view showing a solar cell according to embodiment 1.

Fig. 2 is a partial sectional view of the solar cell of embodiment 1 taken along line II-II in fig. 1.

Fig. 3 is a flowchart illustrating a method of manufacturing a solar cell according to embodiment 1.

Fig. 4 is a schematic cross-sectional view of a solar cell according to embodiment 1 after an electrode forming process.

Fig. 5A is a plan view showing a laser scanning path in a laser processing process according to a comparative example.

Fig. 5B is a plan view showing a laser scanning path in the laser processing process according to embodiment 1.

Fig. 6A is a partial sectional view of the solar cell in the manufacturing process according to embodiment 1, taken along line VIa-VIa in fig. 5B.

Fig. 6B is a partial sectional view of the solar cell in the manufacturing process according to embodiment 1, taken along line VIb-VIb in fig. 5B.

Fig. 7A is a partial sectional view of the solar cell according to embodiment 1 after the base layer removing process at a position corresponding to line VIa-VIa in fig. 5B.

Fig. 7B is a partial sectional view of the solar cell according to embodiment 1 after the base layer removing process at a position corresponding to the line VIb-VIb in fig. 5B.

Fig. 8 is a partial sectional view of the solar cell according to embodiment 1 after the conductive layer removing step.

Fig. 9 is a plan view showing a solar cell according to modification 1 of embodiment 1.

Fig. 10 is a plan view showing a laser scanning path in the laser processing step according to modification 1 of embodiment 1.

Fig. 11 is a plan view showing a laser scanning path in the laser processing step according to modification 2 of embodiment 1.

Fig. 12A is a partial sectional view taken along the line XIIa-XIIa in fig. 11 after the laser processing step of the solar cell according to modification 2 of embodiment 1.

Fig. 12B is a partial sectional view taken along line XIIb-XIIb in fig. 11 after the laser processing step of the solar cell according to modification 2 of embodiment 1.

Fig. 13 is a partial sectional view of a solar cell according to modification 2 of embodiment 1 after the conductive layer removing step.

Fig. 14 is a partial sectional view of a solar cell according to modification 3 of embodiment 1.

Fig. 15 is a plan view showing a laser scanning path in the vicinity of the short side of the solar cell according to embodiment 1.

Fig. 16 is an enlarged view of the region C in fig. 15.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below all show a specific example of the present invention. Therefore, the numerical values, shapes, materials, constituent elements, arrangement of constituent elements, connection methods, steps, and the order of steps shown in the following embodiments are merely examples, and do not limit the scope of the present invention. Therefore, among the components in the following embodiments, components that are not recited in the independent claims representing the uppermost concept of the present invention will be described as arbitrary components.

Moreover, each figure is a schematic diagram, and not necessarily an exact diagram. In the drawings, substantially the same components are denoted by the same reference numerals, and redundant description thereof may be omitted or simplified.

The expression "substantially" includes the meaning of being substantially perpendicular, and for example, the description of "substantially perpendicular" includes not only the meaning of being completely perpendicular but also the meaning of being substantially perpendicular. For example, the expression "substantially" is intended to indicate a case where a difference of about a few percent is also included.

In each drawing, the Z-axis direction is, for example, a direction perpendicular to the light receiving surface of the solar cell. The X-axis direction and the Y-axis direction are directions orthogonal to each other and to the Z-axis direction. For example, in the following embodiments, the term "plan view" refers to a view from the Z-axis direction. In the following embodiments, the "sectional view" refers to a cross section obtained by cutting the solar cell on a plane (for example, a plane defined by a Z axis and an X axis) orthogonal to the light receiving surface of the solar cell, and is viewed from a direction (for example, a Y axis direction) substantially orthogonal to the cross section.

(embodiment mode 1)

A solar cell according to the present embodiment will be described below with reference to fig. 1 to 8.

[1. Structure of solar cell ]

First, a schematic structure of a solar cell according to the present embodiment will be described with reference to fig. 1 and 2. The solar cells are photoelectric conversion elements (photovoltaic elements) that convert light such as sunlight into electrical energy.

Fig. 1 is a plan view showing a solar cell 1 according to the present embodiment. Fig. 1 is a plan view of the solar cell 1 as viewed from the back side. Specifically, (a) of fig. 1 is a plan view showing the solar cell 1 according to the present embodiment, and (b) of fig. 1 is an enlarged plan view of a broken-line frame of (a) of fig. 1. Fig. 2 is a partial sectional view of the solar cell 1 according to the present embodiment taken along line II-II of fig. 1 (a). In fig. 2, a light receiving surface 10a on which light is incident is illustrated as being located on the lower side with respect to the paper surface.

As shown in fig. 2, the solar cell 1 has a semiconductor substrate 10 made of a semiconductor material. The semiconductor substrate 10 can be made of, for example, crystalline silicon or the like. In the present embodiment, an example in which the semiconductor substrate 10 is composed of n-type crystalline silicon will be explained. The crystalline silicon includes single crystalline silicon or polycrystalline silicon. The semiconductor substrate 10 may also be p-type crystalline silicon. The material of the semiconductor substrate 10 may be a compound semiconductor such as GaAs or InP.

The semiconductor substrate 10 has a light-receiving surface 10a on which light is incident and a back surface 10b opposite to the light-receiving surface 10 a. The semiconductor substrate 10 receives light on the light receiving surface 10 a. The back surface 10b is a surface on which light is not directly incident. In the solar cell 1 according to the present embodiment, a semiconductor substrate 10 of a substantially octagonal shape is used in which a long side along the X or Y direction and a short side along a direction intersecting both the X axis and the Y axis are alternately arranged along the outer periphery.

On the light receiving surface 10a of the semiconductor substrate 10, there are provided in order: the substantially intrinsic i-type semiconductor layer 20i has an n-type semiconductor layer 20n of the same conductivity type as the semiconductor substrate 10, and also serves as an anti-reflection layer 19 (protective layer) as a protective film. The i-type semiconductor layer 20i can be made of substantially intrinsic i-type amorphous silicon, for example. The n-type semiconductor layer 20n can be made of, for example, n-type amorphous silicon. The antireflection layer 19 can be made of, for example, silicon nitride. The antireflection layer 19 also has a function of protecting the i-type semiconductor layer 20i and the n-type semiconductor layer 20 n.

On the back surface 10b of the semiconductor substrate 10, an n-type semiconductor layer 13n and a p-type semiconductor layer 12p are arranged.

The n-type semiconductor layer 13n is disposed on a part of the back surface 10 b. The n-type semiconductor layer 13n can be formed of, for example, n-type amorphous silicon or the like. A substantially intrinsic i-type semiconductor layer 13i is disposed between the n-type semiconductor layer 13n and the back surface 10 b. The i-type semiconductor layer 13i can be formed of substantially intrinsic i-type amorphous silicon or the like, for example.

The p-type semiconductor layer 12p is disposed on at least a part of the back surface 10b where the n-type semiconductor layer 13n is not disposed. Substantially the entire back surface 10b is covered with the p-type semiconductor layer 12p and the n-type semiconductor layer 13 n.

The p-type semiconductor layer 12p can be made of p-type amorphous silicon containing a p-type dopant such as boric acid, for example. A substantially intrinsic i-type semiconductor layer 12i is disposed between the p-type semiconductor layer 12p and the back surface 10 b. The i-type semiconductor layer 12i can be made of substantially intrinsic i-type amorphous silicon or the like, for example.

From the viewpoint of photoelectric conversion efficiency, it is desirable that the n-type semiconductor layer 13n and the i-type semiconductor layer 13i, and the p-type semiconductor layer 12p and the i-type semiconductor layer 12i be formed with each other along one direction parallel to the back surface 10 b. In this embodiment, the n-type semiconductor layer 13n and the i-type semiconductor layer 13i, and the p-type semiconductor layer 12p and the i-type semiconductor layer 12i are provided to extend in the X-axis direction and to be inserted into each other in the Y-axis direction. That is, the n-type semiconductor layer 13n and the i-type semiconductor layer 13i, and the p-type semiconductor layer 12p and the i-type semiconductor layer 12i are disposed adjacent to each other in the Y-axis direction. The X-axis direction is an example of a first direction, and the Y-axis direction is an example of a second direction intersecting the first direction. Further, hereinafter, the n-type semiconductor layer 13n, the p-type semiconductor layer 12p, and the i-type semiconductor layers 12i and 13i are collectively referred to as semiconductor layers. The semiconductor layer is, for example, directly laminated on the back surface 10b of the semiconductor substrate 10.

Further, the semiconductor layer may be formed to cover a wide range on the back surface 10b of the semiconductor substrate 10. Therefore, the n-type semiconductor layer 13n and the i-type semiconductor layer 13i and the p-type semiconductor layer 12p and the i-type semiconductor layer 12i can be stacked to overlap each other. For example, as shown in the separation portion 21 of fig. 2, one layer may be stacked on another layer without a gap.

An insulating layer (not shown) is formed in the entire region where the i-type semiconductor layer 13i and the n-type semiconductor layer 13n are stacked on the p-type semiconductor layer 12 p. Thereby, the i-type semiconductor layer 12i and the p-type semiconductor layer 12p are insulated from the i-type semiconductor layer 13i and the n-type semiconductor layer 13 n.

An n-side base layer 14n, an n-side conductive layer 15n, and an n-side electrode 16n are stacked on the n-type semiconductor layer 13 n. On the other hand, a p-side base layer 14p, a p-side conductive layer 15p, and a p-side electrode 16p are stacked on the p-type semiconductor layer 12 p. The n-side conductive layer 15n and the p-side conductive layer 15p are collectively referred to as conductive layers. The n-side electrode 16n and the p-side electrode 16p are collectively referred to as electrodes.

As shown in fig. 1(b), the base layer 14 is composed of an n-side base layer 14n, a p-side base layer 14p, and a first bridge portion 18. The present embodiment is characterized in that the base layer 14 has a first bridge portion 18.

The base layer 14 has a function of suppressing contact between the semiconductor layer and the conductive layer, and suppressing alloying of the semiconductor layer and the conductive layer to improve the reflectance of incident light. The substrate layer 14 is, for example, a transparent conductive layer (TCO film) composed of a transparent conductive material. The transparent conductive layer is preferably formed to include, for example, indium oxide (In) having a polycrystalline structure₂O₃) Zinc oxide (ZnO), tin oxide (SnO)₂) And titanium oxide (TiO)₂) And the like. Dopants of tin (Sn), zinc (Zn), tungsten (W), antimony (Sb), titanium (Ti), aluminum (Al), cerium (Ce), gallium (Ga), and the like may be added to these metal oxides. For example, In₂O₃ITO doped with Sn is particularly preferred. The concentration of the dopant can be set to 0 to 20 mass%. The thickness of the transparent conductive layer is, for example, about 50nm to 100 nm.

The base layer 14 is disposed on the semiconductor layer. For example, the base layer 14 is directly laminated on the semiconductor layer.

The base layer 14 is separated into n-side base layers 14n and p-side base layers 14p by a first separation groove 17 having a first separation portion 17a and a second separation portion 17b extending in different directions. That is, the n-side base layer 14n and the p-side base layer 14p are formed to be separated from each other by the first separation grooves 17. Thus, n-side base layer 14n is disposed on n-type semiconductor layer 13n and electrically connected to n-type semiconductor layer 13 n. The p-side base layer 14p is disposed on the p-type semiconductor layer 12p and electrically connected to the p-type semiconductor layer 12 p.

As shown in fig. 1 a and 2, the base layer 14 is also formed below the electrode (for example, between the electrode and the semiconductor layer). As shown in fig. 1 (a), the n-side base layer 14n includes a first n-side base portion 141n extending in the X-axis direction, and a second n-side base portion 142n extending in the Y-axis direction and connecting the X-axis positive-side end portions of the first n-side base portion 141 n. The X-axis positive-side end of the first n-side group base portion 141n is an example of the end of the other side in the first direction. In addition, the p-side base layer 14p includes a first p-side base portion 141p extending in the X-axis direction, and a second p-side base portion 142p extending in the Y-axis direction and connecting the X-axis negative-side end portion of the first p-side base portion 141 p. The X-axis negative-side end portion of the first p-side group base portion 141p is an example of an end portion on one side in the first direction. In the present embodiment, the first n-side group base portion 141n and the first p-side group base portion 141p are configured to be inserted (interposed) with each other. That is, the first n-side group base portion 141n and the first p-side group base portion 141p are disposed adjacent to each other.

In addition, the first separation portion 17a is provided between the first n-side group base portion 141n and the first p-side group base portion 141p extending in the X-axis direction and adjacent in the top view of the solar cell 1, and the second separation portions 17b are provided between the end portion on the X-axis negative side and the second p-side group base portion 142p of the n-side group base layer 14n (specifically, the first n-side group base portion 141n), and the end portion on the X-axis positive side and the second n-side group base portion 142n of the p-side group base layer 14p (specifically, the first p-side group base portion 141p), respectively.

The first bridge portion 18 is disposed between the first separated portion 17a and the second separated portion 17 b. That is, the first bridge 18 separates the first separated portion 17a and the second separated portion 17 b. In the present embodiment, the first bridge portion 18 is provided between the end portion of the first separated portion 17a in the X-axis direction and the second separated portion 17 b. That is, the first bridge portion 18 separates the end portion of the first separated portion 17a in the X-axis direction from the second separated portion 17 b. Thus, the first separated portion 17a and the second separated portion 17b do not intersect with each other in a plan view.

In fig. 1(b), an example is shown in which the first bridge portion 18 separates the first separated portion 17a from the second separated portion 17b at the boundary between the end portion on the X-axis negative side of the n-side group base layer 14n (specifically, the first n-side group base portion 141n) and the p-side group base layer 14p, and the first separated portion 17a is likewise separated from the second separated portion 17b at the boundary between the end portion on the X-axis positive side of the p-side group base layer 14p (specifically, the first p-side group base portion 141p) and the n-side group base layer 14 n. The first bridge portion 18 is provided at least one of the end portion on the X-axis positive side of the plurality of n-side base layers 14n and the boundary of the p-side base layer 14p and the end portion on the X-axis negative side of the plurality of p-side base layers 14p and the boundary of the n-side base layer 14 n. That is, the solar cell 1 may include at least one first bridge part 18. In addition, in fig. 1(b), the shape of the first bridge portion 18 in a plan view is illustrated as an example of a substantially rectangular shape, but the present invention is not limited thereto.

The end portion on the X-axis negative side of the n-side group base layer 14n (specifically, the first n-side group base portion 141n) is an example of a first end portion, and the end portion on the X-axis positive side of the p-side group base layer 14p (specifically, the first p-side group base portion 141p) is an example of a second end portion. In addition, in fig. 1 b, an example is shown in which the length (length in the Y axis direction) of the second separated portion 17b is longer than the interval between the adjacent first separated portions 17a (see fig. 8 a and 8 b, the interval L2).

The first bridge part 18 is disposed at the above-described position so that the n-side base layer 14n and the p-side base layer 14p are connected via the first bridge part 18. The first bridge portion 18 has electrical conductivity because it is made of the same material as the n-side base layer 14n and the p-side base layer 14p, but has a high resistance value, so the n-side base layer 14n and the p-side base layer 14p are electrically conducted only to such an extent that the photoelectric conversion efficiency is not affected. For example, the resistance of the first bridge portion 18 between the n-side base layer 14n and the p-side base layer 14p is 0.01 Ω · cm or more. For example, the length L1 of the first bridge part 18 in the X-axis direction is 30 μm or more, and the length (the width L3 in fig. 8 (a) and 8 (b)) in the Y-axis direction is 30 μm or less. The length of the first bridge portion 18 in the Y-axis direction is substantially equal to the length of the first separated portion 17a in the short-side direction. Further, the length L1 of the first bridge 18 in the X-axis direction may be equal to or less than the length of the first bridge 18 in the Y-axis direction (width L3 in the present embodiment).

The conductive layer is disposed on the base layer 14 and serves as a seed layer for passing current during electroplating. That is, the n-side electrode 16n and the p-side electrode 16p are formed by electrolytic plating using a conductive layer as a seed layer. The thickness of the conductive layer is, for example, about 50nm to 100 nm.

The n-side electrode 16n is an electrode that is formed directly on the n-side conductive layer 15n and collects carriers (electrons) from the n-type semiconductor layer 13 n. The p-side electrode 16p is an electrode formed directly on the p-side conductive layer 15p and collects carriers (holes) from the p-type semiconductor layer 12 p.

In the present embodiment, the n-side electrode 16n is a plating layer disposed on the n-side conductive layer 15n, and the p-side electrode 16p is a plating layer disposed on the p-side conductive layer 15 p. The n-side electrode 16n includes an n-side finger electrode 161n extending in the X-axis direction, and an n-side bus bar electrode 162n extending in the Y-axis direction and connected to an end portion of the n-side finger electrode 161n on the X-axis positive side. The p-side electrode 16p includes a p-side finger electrode 161p extending in the X-axis direction, and a p-side bus bar electrode 162p extending in the Y-axis direction and connecting an end portion of the X-axis negative side of the p-side finger electrode 161 p. In this embodiment, the n-side finger electrode 161n and the p-side finger electrode 161p are configured to be inserted into each other. That is, the n-side finger electrode 161n is disposed adjacent to the first p-side finger electrode 161 p.

The n-side conductive layer 15n, the n-side electrode 16n, the p-side conductive layer 15p, and the p-side electrode 16p may be made of a metal having high conductivity and high light reflectance. For example, the metal may be composed of a metal such as copper (Cu), tin (Sn), titanium (Ti), aluminum (Al), nickel (Ni), silver (Ag), or gold (Au), or an alloy containing one or more of these metals. That is, the n-side conductive layer 15n, the n-side electrode 16n, the p-side conductive layer 15p, and the p-side electrode 16p are metal layers.

In the present embodiment, the n-side conductive layer 15n, the n-side electrode 16n, the p-side conductive layer 15p, and the p-side electrode 16p are made of Cu, for example, from the viewpoint of conductivity, reflectance, material cost, and the like. The thickness of the Cu layer is, for example, about 10 to 20 μm.

As described above, the solar cell 1 according to the present embodiment is a back junction type solar cell. If the n-side electrode 16n and the p-side electrode 16p are formed by printing or the like, the n-side conductive layer 15n and the p-side conductive layer 15p may not be provided.

[2. method for producing solar cell ]

Next, a method of manufacturing the solar cell 1 described above will be described with reference to fig. 3 to 8.

Fig. 3 is a flowchart illustrating a method of manufacturing a solar cell according to the present embodiment. The manufacturing method according to the present embodiment is characterized by a laser processing step.

As shown in fig. 3, first, a semiconductor layer forming step (S10) of forming an n-type semiconductor layer 13n and a p-type semiconductor layer 12p extending in a first direction (in the present embodiment, the X-axis direction) and provided adjacent to each other in a second direction (in the present embodiment, the Y-axis direction) intersecting the first direction on the back surface 10b of the semiconductor substrate 10 having the light receiving surface 10a on which light is incident and the back surface 10b opposite to the light receiving surface 10a is performed. In the semiconductor forming process, the semiconductor substrate 10 is placed in a vacuum chamber, and an i-type semiconductor layer and an n-type semiconductor layer are sequentially stacked by Plasma Enhanced Chemical Vapor Deposition (PECVD) or sputtering. In the semiconductor forming step, a semiconductor layer or the like is also formed on the light receiving surface 10 a.

In the semiconductor forming step, first, an i-type semiconductor layer 20i and an n-type semiconductor layer 20n are stacked on the light receiving surface 10a of the semiconductor substrate 10, and an i-type semiconductor layer 12i, a p-type semiconductor layer 12p, and an insulating layer (not shown) are stacked on the rear surface 10 b. The insulating layer can be formed, for example, in the same configuration as the antireflection layer 19.

In the lamination step of laminating the i-type semiconductor layers 12i and 20i by PECVD, for example, hydrogen (H) gas is supplied thereto₂) Diluted silane gas (SiH)₄) Used as a raw material gas. In the stacking step of stacking the n-type semiconductor layers 13n and 20n, for example, Phosphine (PH) is added₃) With combined use of hydrogen (H)₂) Diluted Silane (SiH)₄) Used as a raw material gas. In the step of stacking the p-type semiconductor layer 12p, for example,diborane (B2H6) was added and hydrogen (H) was used₂) Dilute disilane (SiH)₄) Used as a raw material gas.

Then, the layers stacked on the back surface 10b are patterned. First, the insulating layer is partially etched and removed. In the insulating layer etching step, a resist film formed by a coating process such as screen printing or ink jetting, or a photolithography process, is used as a mask. When the insulating layer is silicon oxide (SiO)₂) Silicon nitride (SiN) or silicon oxynitride (SiON), for example, it can be etched using an aqueous Hydrogen Fluoride (HF) solution.

After the etching of the insulating layer is finished, for example, the resist film is removed, and the exposed i-type semiconductor layer 12i and p-type semiconductor layer 12p are etched using the patterned insulating layer as a mask. The i-type semiconductor layer 12i and the p-type semiconductor layer 12p are etched using an alkaline etching solution such as a sodium hydroxide (NaOH) aqueous solution (e.g., a 1 mass% NaOH aqueous solution). Through this step, the patterned i-type semiconductor layer 12i, p-type semiconductor layer 12p, and insulating layer are formed on the back surface 10 b.

Before the i-type semiconductor layer 20i is laminated, a textured structure may be formed on the light receiving surface 10a of the semiconductor substrate 10. The texture structure can be formed by anisotropic etching of the (100) plane using an aqueous solution of potassium hydroxide (KOH), for example.

Subsequently, the i-type semiconductor layer 13i and the n-type semiconductor layer 13n are laminated on the entire region on the back surface 10b except for the edge region. That is, the i-type semiconductor layer 13i and the n-type semiconductor layer 13n are also stacked on the patterned i-type semiconductor layer 12i and the p-type semiconductor layer 12 p. The i-type semiconductor layer 13i and the n-type semiconductor layer 13n can be formed by a PECVD method in the same manner as the i-type semiconductor layer 12i and the p-type semiconductor layer 12 p.

Subsequently, the i-type semiconductor layer 13i and the n-type semiconductor layer 13n stacked on the i-type semiconductor layer 12i and the p-type semiconductor layer 12p are patterned to partially remove the insulating layer. First, the i-type semiconductor layer 13i and the n-type semiconductor layer 13n stacked on the i-type semiconductor layer 12i and the p-type semiconductor layer 12p are partially etched and removed. The region of the i-type semiconductor layer 13i and the n-type semiconductor layer 13n to be removed is a region of the i-type semiconductor layer 12i and the p-type semiconductor layer 12p where the p-side electrode 16p is to be formed in a later step. In the etching of the i-type semiconductor layer 13i and the n-type semiconductor layer 13n, for example, a resist film formed by screen printing or the like is used as a mask, and an alkaline etching solution such as an NaOH aqueous solution is used.

Since the i-type semiconductor layer 13i and the n-type semiconductor layer 13n are generally harder to etch than the i-type semiconductor layer 12i and the p-type semiconductor layer 12p, it is preferable to use a solution having a higher concentration than an aqueous NaOH solution (e.g., a 10 mass% aqueous NaOH solution) or hydrofluoric nitric acid (フッ nitric acid) (HF and HNO) to be used for the i-type semiconductor layer 12i and the p-type semiconductor layer 12p₃Mixed aqueous solutions (e.g., 30 mass% each)). Alternatively, it is also preferable to use the aqueous NaOH solution by heating it to about 70 to 90 ℃ (alkali heat treatment).

Next, after the etching of the i-type semiconductor layer 13i and the n-type semiconductor layer 13n is completed, the resist film is removed, and the exposed insulating layer is etched and removed using an HF aqueous solution with the patterned i-type semiconductor layer 13i and the patterned n-type semiconductor layer 13n used as masks. Thus, by removing a part of the insulating layer, the i-type semiconductor layer 12i and a part of the p-type semiconductor layer 12p are exposed.

Next, on the back surface 10b on which the p-type semiconductor layer 12p and the n-type semiconductor layer 13n are formed, a base layer forming step (S11) for forming the base layer 14 and a conductive layer forming step (S12) for forming the conductive layer 15 on the base layer 14 are performed. The base layer 14 and the conductive layer 15 are laminated on the entire regions of the p-type semiconductor layer 12p and the n-type semiconductor layer 13 n.

Here, the solar cell manufactured in the processes of steps S10 to S12 will be described with reference to fig. 4.

Fig. 4 is a schematic cross-sectional view of the solar cell 1 according to the present embodiment after the electrode forming process.

In the steps of steps S10 to S12, the portions of each constituent element shown in fig. 4 except the n-side electrode 16n, the p-side electrode 16p, and the resist film 22 are formed. The base layer 14 and the conductive layer 15 are formed without interruption.

Referring again to fig. 3, on the conductive layer 15, a resist coating process (S13) for coating a resist on a region where the n-side electrode 16n and the p-side electrode 16p correspond to the separation groove (e.g., a region between the n-side electrode 16n and the p-side electrode 16p shown in fig. 1 (b)) is performed. The resist film 22 formed in the resist coating step is formed along the region of the conductive layer 15 corresponding to the separation portion 21. That is, in the plan view of the solar cell 1 after the resist coating step, the resist film 22 and the separating portion 21 are at least partially overlapped and extend in the direction parallel to each other.

In the resist film application step, the resist film 22 is formed by, for example, screen printing. Therefore, as shown in fig. 4, the resist film 22 has a semi-cylindrical shape. The formation method of the resist film 22 is not limited to the screen printing method, and may be a dispenser method or other methods.

The thickness of the resist film 22 may be a thickness that does not cause residue during laser processing in a laser processing process performed in a later process. Further, the thickness of the resist film 22 may be a thickness at which a trace (かすれ) such as a pinhole does not appear when the resist film 22 is formed. For example, the thickness of the resist film 22 to be free from marks is, for example, 15 μm or more. For example, in the semi-cylindrical resist film 22 shown in fig. 4, the maximum thickness is 15 μm or more. If the amount is less than this value, a portion with a mark is generated, and plating grows from the portion with a mark in the subsequent electrode forming step, which causes short-circuiting.

Subsequently, an electrode forming process is performed, which forms the n-side electrode 16n and the p-side electrode 16p by electrolytic plating by using the conductive layer 15 on which the resist film 22 is formed as a seed layer (S14). Here, since the plating layer is formed in a partitioned manner by the resist film 22, the plating layer is separated, and the n-side electrode 16n and the p-side electrode 16p are obtained. Further, in this process, since the conductive layer 15 is not patterned, the areal density of the current flowing during the plating treatment becomes equal, and the n-side electrode 16n and the p-side electrode 16p have the same thickness.

In the present embodiment, since the n-side electrode 16n and the p-side electrode 16p are composed of Cu layers, Cu plating is performed to form the n-side electrode 16n and the p-side electrode 16 p.

Fig. 4 shows a solar cell in which the n-side electrode 16n and the p-side electrode 16p are formed in step S14. In a region where the resist film 22 is not formed, an n-side electrode 16n and a p-side electrode 16p are formed. As shown in fig. 4, the base layer 14 and the conductive layer 15 are not patterned at step S14. Therefore, for example, the n-type semiconductor layer 13n and the p-type semiconductor layer 12p are electrically connected via the base layer 14 and the conductive layer 15. Thus, the base layer 14 and the conductive layer 15 are partially etched.

In order to partially etch the base layer 14 and the conductive layer 15, a laser processing process for partially removing the resist film 22 by irradiating laser light is first performed (S15). A laser scanning path in the laser processing process will be described with reference to fig. 5A and 5B.

Fig. 5A is a plan view showing a laser scanning path in a laser processing process according to a comparative example. Fig. 5B is a plan view showing a laser scanning path in the laser processing process according to the present embodiment. In fig. 5A and 5B, the scanning path of the laser light is shown by a dotted arrow, and the irradiation range of the laser light is shown by a solid-line frame.

As shown in fig. 5A, in the comparative example, the laser light is scanned along the scanning paths R111 to R113. Specifically, in the scanning on the scanning path R111, the resist film 22 within the irradiation range E111 is irradiated with the laser light. Similarly, in the scanning in R112, 113, the resist film 22 within the irradiation ranges E112, E113 is also irradiated with the laser light.

No laser irradiation is performed in the region where the n-side electrode 16n and the p-side electrode 16p are formed. That is, the laser output is stopped in the region where the n-side electrode 16n and the p-side electrode 16p are formed. That is, in the comparative example, the on/off of the laser output was controlled at the boundary between the region where the n-side electrode 16n and the p-side electrode 16p were formed and the region where they were not formed.

Here, it can be seen that the laser light is excessively irradiated at the four intersection points C. For example, at two intersection points C on the negative side of the X axis, the irradiation range E111 and the irradiation range E112 overlap. That is, at the intersection C, laser light is irradiated in the scanning of the scanning path R111, and laser light is irradiated in the scanning of the scanning path R112. Thereby, the semiconductor layer and the like may be damaged, and the photoelectric conversion efficiency of the solar cell may be lowered. In this embodiment, however, the laser beam can be prevented from being excessively irradiated to the same position. In the present embodiment, laser irradiation at the same position in different scanning paths is referred to as double laser irradiation.

As shown in fig. 5B, in the present embodiment, the laser light is scanned along the scanning paths R1 to R3. For example, the scan paths R1-R3 may be the same as the scan paths R111-R113 shown in FIG. 5A. Specifically, in the scanning of the scanning path R1, the resist film 22 within the irradiation range E1 is irradiated with the laser light. Similarly, in the scanning of the scanning paths R2, R3, the resist film 22 within the irradiation ranges E2, E3 is also irradiated with the laser light. The scanning path R1 includes an outward path for scanning from the irradiation range E3 side toward the irradiation range E2 side (from the X-axis positive side to the X-axis negative side in fig. 5B), and a return path for scanning from the irradiation range E2 side toward the irradiation range E3 side (from the X-axis negative side to the X-axis positive side in fig. 5B). The scanning paths R1 to R3 are set in advance before laser processing. That is, the irradiation ranges E2 and E3 are previously known ranges. Further, fig. 5B shows an example of a range in which each of the irradiation ranges E1 to E3 is linear.

In fig. 5B, there is no region where the laser irradiation range intersects, like the intersection point C in fig. 5A. That is, in the method of manufacturing a solar cell according to the present embodiment, the same position is not irradiated with the laser light twice. This may be accomplished, for example, by controlling the on/off of the output of the laser during scanning along scan path R1.

Specifically, in the scanning path R1 (outbound), the laser output is started at the position P1 that has passed through the irradiation range E3. That is, the laser irradiation is not performed until the position P1 is reached. The distance between the irradiation range E3 and the position P1 is substantially equal to the length L1 shown in fig. 1 (b).

Then, laser irradiation is performed until passing through the position P2. The position P2 is a position that does not pass through the irradiation range E2 on the scanning path R1. That is, in the scanning path R1, the laser irradiation is not performed when the laser passes through the irradiation range E2. The distance between the irradiation range E2 and the position P2 is substantially equal to the distance between the irradiation range E3 and the position P1. This forms an elongated irradiation range E1 from the position P1 to the position P2.

Further, in the scanning path R1 (return), the laser output is started at the position P3 that has passed through the irradiation range E2. That is, no laser irradiation is performed from the position P2 to the position P3. The distance between the irradiation range E2 and the position P3 is substantially equal to the distance between the irradiation range E2 and the position P2.

Then, laser irradiation is performed until reaching the position P4. The position P4 is a position that does not pass through the irradiation range E3 on the scanning path R1. That is, in the scanning path R1, the laser irradiation is not performed when the laser passes through the irradiation range E3. The distance between the irradiation range E3 and the position P4 is substantially equal to the distance between the irradiation range E3 and the position P1. This forms an elongated irradiation range E1 from the position P3 to the position P4.

As described above, in the scanning path R1, the laser output is stopped at the position intersecting the scanning paths R2, R3. For example, in the scanning path R1, the laser output is stopped at a position intersecting the irradiation ranges E2, E3.

Thereafter, in the scanning paths R2 and R3, the irradiation ranges E2 and E3 are irradiated with laser light. For example, in the scanning paths R2, R3, at the boundary between the region where the n-side electrode 16n and the p-side electrode 16p are formed and the region where they are not formed, turning on and off of the laser output is performed.

As described above, in the laser processing process, in the region between the irradiation ranges E2, E3, turning on and off of the laser output in the scanning path R1 (go and return) is performed. Thus, the irradiation range E1 does not intersect (does not overlap) the irradiation ranges E2 and E3, and therefore the same position is not irradiated with the laser light twice. That is, the semiconductor layer and the like can be suppressed from being damaged by the laser light.

In fig. 5B, an example of turning on and off the laser output in the region between the irradiation ranges E2, E3 in the scanning path R1 is explained, but the present invention is not limited thereto. For example, the turning on and off of the laser output may be performed in the region between the two irradiation ranges E1 in the scanning paths R2, R3. Specifically, in the scanning path R1, the turning on and off of the laser output is performed at the boundary between the region where the n-side electrode 16n and the p-side electrode 16p are formed and the region where they are not formed. Thus, in the scanning paths R2, R3, the laser output can be turned on and off in the region between the two irradiation ranges E1.

Here, a solar cell on which a laser processing process has been performed will be described with reference to fig. 6A and 6B.

Fig. 6A is a partial sectional view of the solar cell 1 in the manufacturing process according to the present embodiment, taken along the line VIa-VIa in fig. 5B. That is, fig. 6A is a partial cross-sectional view of a region not irradiated with laser light in the laser processing step. Fig. 6B is a partial sectional view of the solar cell 1 during the manufacturing process according to the present embodiment, taken along the line VIb-VIb in fig. 5B. That is, fig. 6B is a partial cross-sectional view of a region irradiated with laser light in the laser processing step.

As shown in fig. 6A, in a region where the resist film 22 is not irradiated with the laser light, no groove is formed in the resist film 22. That is, the resist film 22 remains in the state formed in step S13.

As shown in fig. 6B, in the region of the resist film 22 irradiated with the laser beam, a groove 22a penetrating the conductive layer 15 is formed in the resist film 22. In fig. 6B, the groove 22a corresponding to the irradiation range E1 is formed.

Referring again to fig. 3, a base layer removing process (S16) of etching the rear surface 10b having the grooves 22a formed in the resist film 22 to form the first separation grooves 17 that separate the base layer 14 into the n-side base layer 14n and the p-side base layer 14p is next performed.

In the underlayer removing step, first, the conductive layer 15 is partially etched using the resist film 22 as a mask. Thereby, in the separation groove, the conductive layer 15 is separated, and the n-side conductive layer 15n and the p-side conductive layer 15p are formed to be separated from each other. It is possible to use, for example, iron chloride (FeCl)₃) The conductive layer 15 is etched with an aqueous solution, hydrochloric acid-hydrogen peroxide or sulfuric acid-hydrogen peroxide. Through this step, a part of the base layer 14 as a transparent conductive layer is exposed.

Subsequently, the exposed base layer 14 is etched using the resist film 22 and the conductive layer 15 separated in the separation groove as a mask. Thereby, the base layer 14 is separated in the first separation groove 17, forming the n-side base layer 14n and the p-side base layer 14p separated from each other (see fig. 7B explained later). The underlayer 14 can be etched using, for example, an aqueous hydrogen chloride (HCl) solution, an aqueous oxalic acid solution, or the like.

Here, the solar cell 1 having been subjected to the base layer removing process will be described with reference to fig. 7A and 7B.

Fig. 7A is a partial sectional view of the solar cell 1 according to the present embodiment after the base layer removing process at a position corresponding to the VIa-VIa line in fig. 5B. That is, fig. 7A is a partial cross-sectional view of a region not irradiated with laser light in the laser processing step. Fig. 7B is a partial sectional view of the solar cell 1 according to the present embodiment after the base layer removing process at a position corresponding to the line VIb-VIb in fig. 5B. That is, fig. 7B is a partial cross-sectional view of a region irradiated with laser light in the laser processing step.

As shown in fig. 7A, in the region of the resist film 22 not irradiated with the laser light, the conductive layer 15 and the base layer 14 are not etched. That is, the conductive layer 15 and the base layer 14 remain in the state formed in steps S11, S12.

As shown in fig. 7B, in the region of the resist film 22 irradiated with the laser beam, a separation groove penetrating through the conductive layer 15 and the underlying layer 14 is formed at a position corresponding to the groove 22a of the resist film 22. For example, in the conductive layer 15, an n-side conductive layer 15n and a p-side conductive layer 15p separated from each other are formed by the separation groove. Further, in the base layer 14, an n-side base layer 14n and a p-side base layer 14p separated from each other are formed by the separation grooves. Among the separation grooves penetrating to the conductive layer 15 and the base layer 14, a portion where the n-side base layer 14n and the p-side base layer 14p are separated is referred to as a first separation groove 17 (a first separation portion 17a in fig. 7B). That is, the first separation groove 17 is a groove for separating the n-side base layer 14n and the p-side base layer 14 p.

Referring again to fig. 3, after the base layer removing process, a resist removing process (S17) of removing the resist film 22, and a conductive layer removing process (S18) of removing a part of the n-side conductive layer 15n and the p-side conductive layer 15p are performed.

In the resist removingIn the removing step, the resist film 22 is removed with an alkaline solution such as NaOH or KOH. Then, in the conductive layer removing step, iron chloride (FeCl) can be used₃) Etching with aqueous solution, hydrochloric acid-hydrogen peroxide, sulfuric acid-hydrogen peroxide.

Here, the solar cell 1 having undergone the resist removing process and the conductive layer removing process will be described with reference to fig. 8.

Fig. 8 is a partial sectional view of the solar cell 1 according to the present embodiment after the conductive layer removing step. Specifically, (a) of fig. 8 is a partial sectional view of the solar cell 1 according to the present embodiment after the conductive layer removing process at a position corresponding to the VIa-VIa line in fig. 5B. That is, fig. 8 (a) is a partial cross-sectional view of a region not irradiated with laser light in the laser processing step. Fig. 8 (B) is a partial sectional view of the solar cell 1 according to the present embodiment after the conductive layer removing process at a position corresponding to the VIb-VIb line in fig. 5B. That is, fig. 8 (b) is a partial cross-sectional view of a region irradiated with laser light in the laser processing step.

As shown in fig. 8 (a), the base layer 14 is not etched in the region of the resist film 22 not irradiated with the laser light. Specifically, the base layer 14 is composed of an n-side base layer 14n, a p-side base layer 14p, and a first bridge portion 18. The first bridge portion 18 is disposed between the n-side base layer 14n and the p-side base layer 14p, and connects the n-side base layer 14n and the p-side base layer 14 p.

The first bridge part 18 is formed at a position where the scanning path R1 intersects the scanning paths R2 and R3 by stopping the laser light in the laser processing process. This position is not included in the irradiation ranges E1 to E3, for example, but included in the region between the irradiation range E1 and the irradiation ranges E2, E3.

As shown in fig. 8 (b), in the region where the resist film 22 is irradiated with the laser light, the underlying layer 14 is etched and separated by the first separating portion 17 a.

As shown in fig. 8 (a) and 8 (b), the width L3 (length in the Y-axis direction) of the first bridge portion 18 is substantially the same as the width of the first separated portion 17 a. The width L3 of the first bridge part 18 is smaller than the width of the second separation groove 23. For example, the width of the second isolation groove 23 is 100 μm to 200 μm, and the width L3 of the first bridge 18 is 30 μm. The width L3 of the first bridge part 18 may be substantially equal to the diameter of the laser spot.

This makes it possible to obtain the solar cell 1 shown in fig. 1 (a) and (b).

In addition, the method of manufacturing the solar cell 1 is not limited to the above method. For example, the order of the steps shown in fig. 3 may be changed. For example, after the electrode forming process is performed, a resist removing process, a conductive layer removing process, and an underlayer removing process may be sequentially performed. In the resist removal step, the resist film 22 in a state in which the grooves 22a shown in fig. 6B are not formed (i.e., the resist film 22 formed in the resist film application step) is removed. In the conductive layer removing step, the conductive layer 15 is removed using the n-side electrode 16n and the p-side electrode 16p as masks. Thereby, the n-side conductive layer 15n and the p-side conductive layer 15p are formed. In the base layer removing step, the exposed base layer 14 is laser-processed to form the first isolation grooves 17. That is, in laser processing, the n-side base layer 14n, the p-side base layer 14p, and the first bridge portion 18 are formed. Even in this case, as shown in fig. 5B, the start and stop of the laser output are controlled so that the laser irradiation is not performed twice at the same position. This makes it possible to obtain the solar cell 1 shown in fig. 1 (a) and (b).

[3. effects, etc. ]

As described above, the solar cell 1 according to the present embodiment is a back junction type solar cell, and includes: a semiconductor substrate 10 having a light receiving surface 10a on which light is incident and a back surface 10b opposite to the light receiving surface 10 a; an n-type semiconductor layer 13n and a p-type semiconductor layer 12p extending in a first direction and disposed adjacent to each other in a second direction intersecting the first direction on the back surface 10b of the semiconductor substrate 10; and a base layer 14 provided on the n-type semiconductor layer 13n and the p-type semiconductor layer 12 p. The base layer 14 includes: an n-side base layer 14n provided on the n-type semiconductor layer 13n and a p-side base layer 14p provided on the p-type semiconductor layer 12p, separated from each other by a first separation groove 17 having a first separation portion 17a and a second separation portion 17b extending in different directions; and a first bridge portion 18 separating the first separation portion 17a and the second separation portion 17b, the n-side base layer 14n having a first n-side base portion 141n extending in the first direction, the p-side base layer 14p having a first p-side base portion 141p disposed adjacent to the first n-side base portion 141n extending in the first direction, the first bridge portion 18 separating the first separation portion 17a and the second separation portion 17b at least one of a boundary of a first end portion of the first n-side base portion 141n on one side in the first direction and the p-side base layer 14p, and a boundary of a second end portion of the first p-side base portion 141p on the other side in the first direction and the n-side base layer 14 n.

Therefore, when laser processing is performed to separate the base layer 14 into the n-side base layer 14n and the p-side base layer 14p, the laser output can be stopped at a position corresponding to the first bridge portion 18. That is, the first separating portion 17a and the second separating portion 17b can be suppressed from crossing. Therefore, it is possible to realize the solar cell 1 that suppresses the laser beam from being irradiated twice to the same position and suppresses damage to the semiconductor layer and the like during laser processing.

Further, the n-side base layer 14n has a second n-side base portion 142n extending in the second direction and connecting the other side end portion in the first direction of the first n-side base portion 141n, and the p-side base layer 14p has a second p-side base portion 142p extending in the second direction and connecting the one side end portion in the first direction of the first p-side base portion 141 p. In a plan view of the solar cell 1, the first separation portion 17a extends in the first direction, and is disposed between the first n-side group base portion 141n and the first p-side group base portion 141p adjacent to each other. The second separating portions 17b are disposed between the first end portion and the second p-side group base portion 142p and between the second end portion and the second n-side group base portion 142n, respectively. The length of the second separated portion 17b in the second direction is greater than the interval L2 between the first separated portions 17a adjacent to each other. The first bridge portion 18 separates an end portion of the first separated portion 17a in the first direction from the second separated portion 17 b.

In this way, even when the first separation grooves 17 are formed by scanning the laser light a plurality of times, it is possible to suppress the laser light from being irradiated twice at the same position. When laser processing is performed, the solar cell 1 in which damage to a semiconductor layer or the like is suppressed can be realized.

Further, the length L1 of the first bridge 18 is equal to or less than the length of the first bridge 18 in the Y-axis direction (width L3 in the present embodiment).

Thereby, the resistance of the first bridge portion 18 can be increased to suppress the influence of the first bridge portion 18 on the carrier collection, and when laser processing is performed, the solar cell 1 in which damage to the semiconductor layer and the like is suppressed can be realized.

As described above, the method for manufacturing a solar cell according to the present embodiment is a method for manufacturing a back junction type solar cell, and includes the steps of: a semiconductor layer forming step (S10) of forming an n-type semiconductor layer 13n and a p-type semiconductor layer 12p extending in a first direction and provided adjacent to each other in a second direction intersecting the first direction on a back surface 10b of the semiconductor substrate 10 having a light receiving surface 10a on which light is incident and the back surface 10b opposite to the light receiving surface 10 a; a base layer forming step (S11) of forming a base layer 14 on the back surface 10b on which the n-type semiconductor layer 13n and the p-type semiconductor layer 12p are formed; a conductive layer forming step (S12) of forming a conductive layer 15 on the base layer 14; a resist forming step (S13) of applying a resist to a region corresponding to the n-type semiconductor layer 13n and the p-type semiconductor layer 12p on the conductive layer 15; an electrode forming step (S14) of forming the n-side electrode 16n and the p-side electrode 16p by electrolytic plating using the conductive layer 15 having the resist film 22 formed thereon in the resist forming step as a seed layer; a laser processing step (S15) of forming a groove 22a penetrating to the conductive layer 15 on the resist film 22 by scanning with a laser after the electrode forming step; a base layer removing step (S16) of etching the rear surface 10b on which the grooves 22a are formed to form first separation grooves 17 for separating the base layer 14 into the n-side base layer 14n and the p-side base layer 14 p; and a resist removal step (S17) of removing the resist film 22 after the base layer removal step. In the laser processing step, by stopping the output of the laser light at a position where the scanning paths R1 to R3 scanned by the laser light intersect, the first isolation groove 17 that separates the first isolation portion 17a and the second isolation portion 17b extending in different directions is formed at the position.

Therefore, by stopping the laser output at the position where the scanning paths R1 to R3 intersect, the solar cell 1 in which the first and second separating portions 17a and 17b are separated by the first bridge portion 18 can be realized.

In addition, since the resist film 22 is removed by the laser beam in the laser processing step, the removed conductive layer 15 and the underlying layer 14 can be prevented from adhering to the periphery thereof, as compared with the case where the conductive layer 15 and the underlying layer 14 are directly removed by the laser beam.

(modification 1 of embodiment 1)

A solar cell according to this modification will be described below with reference to fig. 9 and 10.

Fig. 9 is a plan view showing a solar cell according to the present modification. Specifically, fig. 9 shows a region corresponding to (b) of fig. 1 in the solar cell.

As shown in fig. 9, in the present embodiment, the base layer has an n-side base layer 114n, a p-side base layer 114p, and a first bridge portion 118.

The base layer is separated by the first separating groove 117. Specifically, the base layer is separated into n-side base layer 114n and p-side base layer 114p by first and second separating portions 117a and 117 b.

In the plan view of the solar cell, one end portion of the first separating portion 117a is disposed at the boundary between the first p-side group base portion 141p and the second n-side group base portion 142n (see (a) in fig. 1), and the other end portion is disposed at the boundary between one first n-side group base portion 141n adjacent to the first p-side group base portion 141p and the second p-side group base portion 142 p.

In a plan view of the solar cell, one end portion of the second separating portion 117b is disposed at a boundary between the first p-side group bottom portion 141p and the second n-side group bottom portion 142n, and the other end portion is disposed at a boundary between the other first n-side group bottom portion 141n adjacent to the first p-side group bottom portion 141p and the second p-side group bottom portion 142 p.

The first and second separated portions 117a and 117b each have a shape curved, for example, on the end portion side.

The first bridge portion 118 is disposed between adjacent end portions of the first and second separated portions 117a and 117 b. That is, the first bridge portion 118 separates the first and second separated portions 117a and 117b extending in different directions at the boundary between the n-side base layer 114n and the p-side base layer 114 p.

Next, a method of manufacturing a solar cell according to the present modification will be described with reference to fig. 10. This modification is characterized by the laser processing step shown in fig. 3, and only the laser processing step will be described. The other steps are the same as those in embodiment 1.

Fig. 10 is a plan view showing a laser scanning path in the laser processing step according to the present modification. Specifically, fig. 10 shows a region corresponding to the dashed line region a shown in (a) of fig. 1.

As shown in fig. 10, the laser light is irradiated by scanning along a scanning path R11. Specifically, in the scanning along the scanning path R11, the laser light is irradiated on the resist film 22 within the irradiation range E11. That is, in the present modification, the grooves can be formed in the resist film 22 by one scan.

The irradiation range E11 indicates a range in which the laser light is irradiated in the scanning path R11. The scanning path R11 has a shape at least a part of which is curved. That is, the scanning path R11 has a curved path in the region between the n-side electrode 16n and the p-side electrode 16 p.

On the scanning path R11, the laser light is turned on at a position P11 where the bending scanning is performed. Then, the laser light is irradiated to the position P12. That is, the laser output is turned off before passing through the position where the scanning path R11 intersects. Then, the scanning path R11 is scanned in a state where the laser output is stopped, and the laser output is turned on at the position P13 that is crossed by the scanning path R11. That is, laser irradiation is not performed at the position where the scanning path R11 intersects. That is, laser irradiation is not performed twice at the same position. Then, laser irradiation is performed until the position P14 is reached, and the laser output is stopped at the position P14.

In the laser processing step, the laser output is stopped at a position where the scanning path R11 of the scanning laser intersects, so that the first separating groove 117 in which the first separating portion 117a and the second separating portion 117b extending in different directions are separated by the first bridge portion 118 can be formed at this position. Thereby, the solar cell 1 shown in fig. 9 can be obtained.

As described above, in the solar cell according to the present modification, the n-side base layer 114n has: a second n-side group base portion 142n extending in a second direction intersecting the first direction and connecting the other end portion in the first direction of the first n-side group base portion 141n, the p-side base layer 114p having: a second p-side group base portion 142p extending in the second direction and connecting the other side end portion in the first direction of the first p-side group base portion 141 p. In a plan view of the solar cell, one end portion of the first separating portion 117a is disposed at a boundary between the first p-side group base portion 141p and the second n-side group base portion 142n, and the other end portion is disposed at a boundary between one first n-side group base portion 141n adjacent to the first p-side group base portion 141p and the second p-side group base portion 142 p. Further, in a plan view of the solar cell, one end portion of the second separating portion 117b is provided at a boundary between the first p-side group bottom portion 141p and the second n-side group bottom portion 142n, and the other end portion is provided at a boundary between the other first n-side group bottom portion 141n adjacent to the first p-side group bottom portion 141p and the second p-side group bottom portion 142 p. Thus, the first bridge portion 118 separates the first separated portion 117a from the adjacent end portion of the second separated portion 117 b.

Thus, even when the first separation groove 117 is formed by scanning the laser beam once, it is possible to suppress the laser beam from being irradiated twice at the position where the scanning path R11 intersects, and therefore, it is possible to realize a solar cell in which damage to the semiconductor layer and the like is suppressed when performing laser processing.

(modification 2 of embodiment 1)

A solar cell according to this modification will be described below with reference to fig. 11 to 13. The present modification is characterized in that the irradiation range of the laser beam is irradiated in the laser processing step. That is, the positions where the first separated portion and the second separated portion are formed are different from those in embodiment 1.

Fig. 11 is a plan view showing a laser scanning path in the laser processing step according to the present modification.

In fig. 5B, the laser light is irradiated along the substantially central portion between the n-side electrode 16n and the p-side electrode 16p, but in the present modification, the laser light is irradiated along a position between the n-side electrode 16n and the p-side electrode 16p and near one of the n-side electrode 16n and the p-side electrode 16p, as shown in fig. 11.

In fig. 11, laser light is irradiated through the scanning paths R21 to R23, but the scanning path R21 scans a position between the n-side electrode 16n and the p-side electrode 16p and near the n-side electrode 16n among the n-side electrode 16n and the p-side electrode 16 p. Therefore, the irradiation range E21 is formed between the n-side electrode 16n and the p-side electrode 16p and near the position of the n-side electrode 16n among the n-side electrode 16n and the p-side electrode 16 p. For example, the irradiation range E21 is formed between the n-side finger electrode 161n and the p-side finger electrode 161p (see fig. 1 a) and is located close to the n-side finger electrode 161 n.

Further, the scanning path R22 scans a position between the n-side electrode 16n and the p-side electrode 16p and close to the n-side electrode 16 n. Therefore, the irradiation range E22 is formed between the n-side electrode 16n and the p-side electrode 16p and at a position close to the n-side electrode 16 n. For example, the irradiation range E22 is formed between the n-side finger electrode 161n and the p-side main-gate electrode 162p (see fig. 1 a) and is located close to the n-side main-gate electrode 162 n.

The scanning path R23 scans a position between the n-side electrode 16n and the p-side electrode 16p and close to the n-side electrode 16 n. Therefore, the irradiation range E23 is formed between the n-side electrode 16n and the p-side electrode 16p and at a position close to the n-side electrode 16 n. For example, the irradiation range E23 is formed between the p-side finger electrode 161p and the n-side main-gate electrode 162n (see fig. 1 a) and is located close to the n-side main-gate electrode 162 n.

Positions P21 through P24 correspond to positions P1 through P4, respectively, as shown in FIG. 5B. That is, the laser irradiation is started at positions P21, P23, and stopped at positions P22, P24. That is, the irradiation range E21 is formed between the irradiation range E22 and the irradiation range E23.

Fig. 12A is a partial cross-sectional view taken along the line XIIa-XIIa in fig. 11 after the laser processing process of the solar cell according to the present modification. Fig. 12B is a partial sectional view taken along line XIIb-XIIb of fig. 11 after the laser processing process of the solar cell according to the present modification.

As shown in fig. 12A, in the region of the resist film 22 not irradiated with the laser light, no groove is formed in the resist film 22. That is, the resist film 22 remains in the state formed in step S13 shown in fig. 3.

As shown in fig. 12B, in the region of the resist film 22 irradiated with the laser beam, a groove 122a penetrating the conductive layer 15 is formed in the resist film 22. In fig. 12B, a groove 122a corresponding to the irradiation range E21 is formed. Specifically, in the cross-sectional view of the solar cell, the groove 122a is formed between the position where the thickness of the resist film 22 is the largest and the n-side electrode 16n or the p-side electrode 16 p. In the present embodiment, the resist film 22 is formed in a semi-cylindrical shape. The position where the thickness of the resist film 22 is the largest is located at the approximate center of the width (length in the Y-axis direction) of the resist film 22. For example, the position where the thickness of the resist film 22 is the largest is substantially the center between the n-side electrode 16n and the p-side electrode 16 p. Therefore, in the cross-sectional view of the solar cell, the groove 122a is formed at a position close to one of the n-side electrode 16n and the p-side electrode 16 p. In the present embodiment, the groove 122a is formed at a position close to the n-side electrode 16 n.

Fig. 13 is a partial sectional view of the solar cell according to the present modification after the base layer removing step. Specifically, (a) of fig. 13 is a partial cross-sectional view of the solar cell according to the present modification after the base layer removing step, taken along the line XIIa-XIIa of fig. 11. Fig. 13 (b) is a partial cross-sectional view of the solar cell according to the present modification taken along line XIIb-XIIb of fig. 11 after the base layer removing step.

As shown in fig. 13 (a), the base layer 14 is not etched in the region of the resist film 22 not irradiated with the laser light. Specifically, the base layer 14 includes an n-side base layer 214n, a p-side base layer 214p, and a first bridge portion 218. The first bridge portion 218 is disposed between the n-side base layer 214n and the p-side base layer 214p, and connects the n-side base layer 214n and the p-side base layer 214 p.

As shown in fig. 13 (b), in the region of the resist film 22 irradiated with the laser light, the underlying layer 14 is etched and separated by the first separation portion 217 a.

As shown in fig. 13 (a) and 13 (b), in the cross-sectional view of the solar cell, the first bridge portion 218 and the first separation portion 217a are formed on the p-side electrode 16p side among the n-side electrode 16n and the p-side electrode 16 p.

Although not shown, in the cross-sectional view of the solar cell, the second separated portion formed by the irradiation range E22 is formed on the p-side electrode 16p side. In the cross-sectional view of the solar cell, the second separated portion formed by the irradiation field E23 is formed on the n-side electrode 16n side. A separation groove is formed by the first separation portion 217a and the second separation portion.

As described above, the solar cell according to the present modification includes: an n-side electrode 16n formed of a plating film and provided on the n-side conductive layer 15 n; and a p-side electrode 16p formed of a plated film provided on the p-side conductive layer 15 p. In a plan view of the solar cell, the first separation groove (e.g., the first separation portion 17a) is located between the n-side electrode 16n and the p-side electrode 16p and near one of the n-side electrode 16n and the p-side electrode 16 p.

Thus, when the thickness of the resist film 22 is large, a portion of the resist film 22 different from the portion having the largest thickness can be processed by laser light, and the groove 122a can be formed without increasing the laser output. That is, even if the thickness of the resist film 22 is large, it is possible to suppress an increase in damage to the semiconductor layer due to an increase in laser output. Therefore, in the present modification, it is possible to realize a solar cell in which damage to the semiconductor layer and the like is suppressed when processing is performed by laser light.

As described above, according to the method of manufacturing a solar cell of the present modification, in the laser processing step, the laser beam is scanned between the position where the thickness of the resist film 22 is the largest and the n-side electrode 16n or the p-side electrode 16p in the cross-sectional view of the solar cell. For example, in the laser processing step, the laser beam may be scanned at a position close to one of the n-side electrode 16n and the p-side electrode 16p in the cross-sectional view of the solar cell.

Therefore, when the thickness of the resist film 22 is large, the laser beam can be used to process a portion different from the portion where the thickness of the resist film 22 is the largest, and the groove 122a can be formed without increasing the laser output. That is, even if the thickness of the resist film 22 is large, it is possible to suppress an increase in damage to the semiconductor layer due to an increase in laser output. In addition, since the portion of the resist film 22 having the largest thickness is not processed by the laser beam, the generation of film residue of the resist film 22 after the laser beam processing can be suppressed. Therefore, when laser processing is performed, it is possible to realize a solar cell in which damage to a semiconductor layer or the like is suppressed and the yield is improved.

(modification 3 of embodiment 1)

A solar cell according to this modification will be described below with reference to fig. 14.

Fig. 14 is a partial sectional view of a solar cell according to the present modification. Specifically, (a) of fig. 14 is a partial sectional view of the solar cell according to the present modification at a position corresponding to the VIa-VIa line in fig. 5B. Fig. 14 (B) is a partial sectional view of the solar cell according to this modified example at a position corresponding to the line VIb-VIb in fig. 5B. In this modification, the conductive layer removing step shown in fig. 3 is not performed.

As shown in fig. 14 (a), the conductive layer is composed of an n-side conductive layer 315n, a p-side conductive layer 315p, and a second bridge part 24. The second bridge portion 24 is formed on the first bridge portion 18. The second bridge portion 24 is formed on the first bridge portion 18 shown in fig. 1(b), for example. The solar cell of the present modification includes a separation groove that separates the conductive layer into an n-side conductive layer 315n and a p-side conductive layer 315p at positions corresponding to the first separation portion 17a and the second separation portion 17b shown in fig. 1 (b). That is, the conductive layer has a separation groove composed of two separation portions extending in different directions. A second bridge 24 separates the two separate portions. A separation groove (for example, the first separation portion 23a in fig. 14 (b)) that separates the conductive layer into the n-side conductive layer 315n and the p-side conductive layer 315p is an example of the second separation groove.

By disposing the second bridge portion 24 at the above-described position, the n-type semiconductor layer 13n and the p-type semiconductor layer 12p are connected via the second bridge portion 24. When the n-type semiconductor layer 13n and the p-type semiconductor layer 12p are connected via the second bridge portion 24 with high resistance that does not affect the photoelectric conversion efficiency, even if the second bridge portion 24 is formed, it has little effect on the photoelectric conversion efficiency. The resistance of the second bridge part 24 is substantially the same as the resistance of the first bridge part 18, for example. For example, the resistance of the second bridge part 24 is 1k Ω/□ or more. For example, the sheet resistance of the conductive layers (the second bridge part 24, the n-side conductive layer 315n, and the p-side conductive layer 315p in the present embodiment) is 1k Ω/□ or more. In addition, for example, the size of the second bridge portion 24 is substantially equal to the size of the first bridge portion 18 in plan view. Therefore, the resistance of the second bridge part 24 is high, and conduction between the n-side conductive layer 315n and the p-side conductive layer 315p can be suppressed.

The process of increasing the resistance value of the second bridge portion 24 may be performed after the resist removal process. For example, heat treatment may be performed in an oxygen atmosphere to perform treatment such as high resistance.

As shown in fig. 14 (b), the conductive layer is separated into n-side conductive layer 315n and p-side conductive layer 315p by first separating portion 23 a. The width (length in the Y axis direction) of the first separating portion 23a is substantially equal to the width of the first separating portion 17a, for example.

As described above, the solar cell according to the present modification includes the conductive layer 15 provided on the n-side base layer 14n and the p-side base layer 14 p. The conductive layer 15 includes: an n-side conductive layer 315n provided on the n-side base layer 14n and a p-side conductive layer 315p provided on the p-side base layer 14p, which are separated from each other by a second separation groove (e.g., a first separation portion 23a), and a second bridge portion 24 provided on the first bridge portion 18 and separating the second separation groove.

Therefore, even if the step of removing the conductive layer shown in fig. 3 is omitted, for example, in the case of performing laser processing, it is possible to realize a solar cell in which damage to the semiconductor layer and the like is suppressed.

(modification 4 of embodiment 1)

A solar cell according to this modification will be described below with reference to fig. 15 and 16.

Fig. 15 is an enlarged view of the vicinity of the short side of the solar cell according to the present modification. Specifically, a region B in fig. 15 is an enlarged view of the region B in fig. 1. In fig. 15, the region B is rotated by 180 degrees with respect to fig. 1 to facilitate understanding of the drawing. In fig. 15, R32a and R32b denote laser scanning paths. Fig. 16 is an enlarged view of the region C in fig. 15, showing the laser scanning path and the laser irradiation ranges E31, E32, and E33 in the region C.

In this modification, a laser scanning path in the vicinity of the short side (the vicinity of the corner) of the solar cell will be described. As in the present modification, when the shape of the solar cell is, for example, a substantially octagonal shape having long sides and short sides, the X coordinate of the tip of the finger electrode 161pe provided at both ends of the solar cell in the Y axis direction is different from the X coordinate of the tip of the finger electrode 161p provided at the center of the solar cell in the Y axis direction. That is, the X coordinate of the leading end of the finger electrode 161pe is smaller than the X coordinate of the leading end of the finger electrode 161 p. At this time, as in R32b of fig. 15, if laser scanning of the leading end portions of a plurality of finger electrodes 161pe (two finger electrodes 161pe in the example of fig. 15) is performed at a time, the laser scanning is simple. For example, when laser scanning is performed only in a scanning path (for example, the scanning path R32a) in a direction substantially parallel to the Y axis, the front ends of the finger electrodes 161p are irradiated with laser light on the scanning path R32a, and the respective front ends of the two finger electrodes 161pe are irradiated with laser light on scanning paths in a direction parallel to the Y axis, respectively. That is, three laser scans need to be performed. On the other hand, in the present modification, the laser beam can be irradiated to a desired region by two laser scans on the scanning paths R32a and R32 b. The both end portions in this modification are regions extending from the outer peripheral portion of the solar cell toward the central portion of the solar cell by several millimeters to several centimeters. The scanning path R32b is a direction intersecting both the X axis and the Y axis, and is appropriately determined by the X coordinate and the like of the leading end of each of the finger electrodes 161 pe.

The laser scanning path R32 preferably intersects the finger electrode 161n on the outer peripheral side of the scanning path R31. For this reason, the width of the resist film 22 in the X-axis direction near the leading end of the finger electrode 161pe may be wider than the width of the resist film 22 near the leading end of the finger electrode 161 p. As shown in fig. 16, in the vicinity of the short side of the solar cell, the laser scanning path R32b extends through the arrangement position of the resist film 22 in the direction intersecting both the X axis and the Y axis. That is, the laser irradiation range E33 also extends in a direction intersecting both the X axis and the Y axis. Since the resist film 22 disposed near the leading end of the finger electrode 161pe has a wide width in the X-axis direction, the laser irradiation range E33 can be formed without damaging the leading end of the finger electrode 161 pe. The width of the resist film 22 in the X-axis direction may be as wide as necessary for forming the laser irradiation range E33.

In the present modification, the finger electrodes 161p and the finger electrodes 161pe have been described, and the same processing may be performed for the finger electrodes 161 n. That is, the laser beam can be irradiated on the tip of the finger electrode 161ne (not shown) provided at both ends of the solar cell in the Y axis direction through the same laser scanning path as described above.

In the present modification, the solar cell is described as being substantially octagonal, but the form of the solar cell is not limited to this. In the present modification, the busbar electrodes 161pe and 161p provided at both ends of the solar cell in the Y axis direction are described separately. However, it is not always necessary to provide such an electrode arrangement form at both end portions of the solar cell. When the arrangement pattern of the electrodes is deformed to simplify the laser scanning, the present modification can be applied even if the portion of the pattern deformed is the center portion in the Y-axis direction of the solar cell. Needless to say, if the same manufacturing process is used, this modification can be applied not only to the back junction type solar cell but also to the double-sided light receiving type solar cell.

(other embodiments)

The solar cell and the like of the present invention have been described above based on the embodiments and the modified examples, but the present invention is not limited to the embodiments and the modified examples.

For example, in the above-described embodiment and modification, the i-type semiconductor layer 12i and the p-type semiconductor layer 12p are laminated, and then the i-type semiconductor layer 13i and the n-type semiconductor layer 13n are laminated, but the i-type semiconductor layer 13i and the n-type semiconductor layer 13n may be laminated first.

The order of the steps in the method for manufacturing a solar cell described in the above embodiment and modification is an example, and the present invention is not limited to this. In addition, some steps may not be performed.

In the method for manufacturing a solar cell described in the above embodiment and modification, the respective steps may be performed in one step or may be performed in separate steps. "implemented in one process" is intended to include: each step is performed using one apparatus, continuously, or at the same position. The respective steps are performed by using respective apparatuses, performed at different times (for example, on different days), or performed at different places.

The present invention also includes a mode obtained by applying various modifications that can be conceived by those skilled in the art to each of the embodiments and the modifications, and a mode realized by arbitrarily combining the constituent elements and functions in each of the embodiments and the modifications without departing from the scope of the present invention.

Description of the reference numerals

1 solar cell

10 semiconductor substrate

10a light receiving surface

10b back side

Type 12p p semiconductor layer

13n n type semiconductor layer

14 base layer

14n, 214n n side substrate layer

14p p side substrate

15 conductive layer

15n, 315n n side conductive layer

15p, 315p p side conductive layer

16n n side electrode

16p p side electrode

17. 117 first separating tank

17a, 117a, 217a first separating portion

17b, 117b second separating part

18. 118, 218 first bridge part

22 resist film

22a, 122a groove

23 second separating tank

23a first separation part

24 second bridge part

141n first n side group bottom

141p first p side group bottom

142n second n side group bottom

142p second p side group bottom

L1 length

L3 width

R1-R3, R11, R21-R23, R31, R32a and R32b scanning paths.