WO2014020693A1

WO2014020693A1 - Method for producing solar cell

Info

Publication number: WO2014020693A1
Application number: PCT/JP2012/069436
Authority: WO
Inventors: 島　正樹; 小林　伸二
Original assignee: 三洋電機株式会社
Priority date: 2012-07-31
Filing date: 2012-07-31
Publication date: 2014-02-06
Also published as: JP6032623B2; JPWO2014020693A1

Abstract

Provided is a method that can produce a solar cell at an improved yield. In a treatment step, a plurality of substrates (11) are treated by immersing, in a chemical (13) retained in a chemical tank (12), the plurality of substrates (11) disposed along a first direction, and supplying gas bubbles (14) towards the plurality of substrates (11) in the chemical (13) from a plurality of gas bubble generating openings (16) of gas bubble generating units (15a-15d) disposed below the plurality of substrates (11) in the chemical tank (12). In a plan view, the treatment step is performed in the state of the plurality of substrates (11) being disposed in a manner so that gas bubble generating openings (16) are positioned between adjacent substrates (11) in the first direction.

Description

Manufacturing method of solar cell

The present invention relates to a method for manufacturing a solar cell.

In recent years, solar cells have been attracting attention as an energy source with a low environmental load. In particular, attention has been focused on solar cells having a substrate made of a semiconductor material such as a crystalline silicon substrate.

When manufacturing a solar cell including a substrate made of such a semiconductor material, it is necessary to perform a step of wet etching the substrate, for example, a step of forming an uneven structure called a texture structure on the surface of the substrate made of a semiconductor material ( For example, see Patent Document 1).

JP-A-10-303443

After performing the process of etching the substrate, a process of cleaning the substrate with a liquid is required. In this cleaning process, the above-described etching process, etc., it is necessary to make the entire substrate uniformly contact with the chemical solution. This is because if a portion where the substrate is not sufficiently cleaned or a portion where etching is insufficient is generated on the substrate, desired solar cell characteristics may not be obtained, and the yield rate may be reduced.

The main object of the present invention is to provide a method capable of producing solar cells with an improved yield rate.

The method for manufacturing a solar cell according to the present invention relates to a method for manufacturing a solar cell having a substrate made of a semiconductor material. The method for manufacturing a solar cell according to the present invention includes a processing step. In the processing step, the plurality of substrates arranged along one direction are immersed in the chemical solution stored in the chemical solution tank, and the plurality of bubble generation ports of the bubble generation unit arranged below the plurality of substrates in the chemical solution tank Then, bubbles are supplied toward the plurality of substrates in the chemical solution to process the plurality of substrates. In a plan view, the processing step is performed in a state where a plurality of substrates are arranged so that the bubble generating port is positioned between adjacent substrates in one direction.

According to the present invention, it is possible to provide a method capable of manufacturing solar cells with an improved yield rate.

FIG. 1 is a schematic perspective view of a cassette according to the first embodiment. FIG. 2 is a schematic plan view of the cassette according to the first embodiment. FIG. 3 is a schematic front view for explaining the processing steps in the first embodiment. In FIG. 3, the relationship between the bubble and the bubble generation port and the substrate is schematically drawn, which is different from the actual case. FIG. 4 is a schematic plan view showing the relationship between the bubble supply port and the substrate in the first embodiment. FIG. 5 is a time chart for explaining the timing of generating bubbles from the pipes 15a to 15d in the first embodiment. FIG. 6 is a schematic plan view showing the relationship between the bubble supply port and the substrate in the second embodiment. FIG. 7 is a schematic plan view showing the relationship between the bubble supply port and the substrate in the third embodiment.

Hereinafter, an example of a preferable embodiment in which the present invention is implemented will be described. However, the following embodiment is merely an example. The present invention is not limited to the following embodiments.

In each drawing referred to in the embodiment and the like, members having substantially the same function are referred to by the same reference numerals. The drawings referred to in the embodiments and the like are schematically described, and the ratio of the dimensions of the objects drawn in the drawings may be different from the ratio of the dimensions of the actual objects. The dimensional ratio of the object may be different between the drawings. The specific dimensional ratio of the object should be determined in consideration of the following description.

(First embodiment)
In the present embodiment, a method for manufacturing a solar cell having a substrate made of a semiconductor material will be described. The substrate made of a semiconductor material may be a crystalline silicon substrate. That is, the method for manufacturing a solar cell according to the present invention may be a method for manufacturing a crystalline silicon solar cell.

A solar cell includes, for example, a substrate made of a semiconductor material, a first semiconductor layer having one conductivity type disposed on one principal surface of the substrate, and another disposed on the other principal surface of the substrate. You may provide the 2nd semiconductor layer which has a conductivity type, the 1st electrode distribute | arranged on the 1st semiconductor layer, and the 2nd electrode distribute | arranged on the 2nd semiconductor layer .

Moreover, the solar cell includes, for example, a substrate made of a semiconductor material, first and second semiconductor layers disposed on one main surface of the substrate, and a first disposed on the first semiconductor layer. It may be a back junction solar cell including an electrode and a second electrode disposed on the second semiconductor layer.

An uneven structure called a texture structure may be provided on at least one main surface of the substrate made of a semiconductor material in order to increase the light incident efficiency on the substrate. The texture structure can be formed, for example, by anisotropically etching the surface of the crystalline silicon substrate.

The manufacturing method of the solar cell according to the present embodiment includes a processing step of processing by immersing a substrate made of a semiconductor material in a chemical solution. Specific examples of the processing step include a cleaning step of cleaning the substrate by immersing the substrate in a cleaning solution, and an etching step of etching the substrate by immersing the substrate in an etching solution. As a treatment process, it is preferable to perform at least one of a cleaning process and an etching process.

For example, there may be a case where a plurality of processing steps are performed when manufacturing a solar cell, such as a case where a cleaning step is performed after an etching step. In such a case, at least one of the plurality of processing steps may be the processing step described in the present embodiment, and all the processing steps are performed in the same manner as the processing step described in the present embodiment. There is no necessity.

The substrate used for the processing step may be composed only of a substrate made of a semiconductor material, or a substrate made of a semiconductor material in which a layer such as a semiconductor layer or a protective layer, or a member such as an electrode is provided on the surface. It may be.

Hereinafter, details of the processing steps in the present embodiment will be described in detail with reference to FIGS.

(Set the substrate 11 to the cassette 10)
First, for example, a plurality of substrates 11 are set in a cassette 10 as shown in FIGS. Here, the substrate 11 may be a substrate made of a semiconductor material, or may be a substrate made of a semiconductor material in which a semiconductor layer or the like is disposed on the surface.

The cassette 10 is not particularly limited as long as it has a shape capable of holding a plurality of substrates 11 spaced apart from each other along one direction. In the present embodiment, a plurality of recesses 10 a are provided on both side surfaces of the cassette 10. The concave portion 10a provided on one side surface of the cassette 10 and the concave portion 10a provided on the other side surface face each other in the y-axis direction. The substrate 11 is inserted into the pair of recesses 10a facing each other in the y-axis direction. As a result, the plurality of substrates 11 are held in a state of being spaced apart from each other along the x-axis direction.

The recess 10a extends along the z-axis direction which is the vertical direction, and the interval between the two side walls constituting the recess 10a is widened toward the substrate 11 side. That is, the interval between the two side walls constituting the recess 10a is widened toward the center side in the y-axis direction. For this reason, it is suppressed that the board | substrate 11 contacts the cassette 10 in a wide area.

The side wall portions located on both sides in the x direction of the cassette 10 are provided with cutouts 10b and openings for allowing the chemical solution to pass therethrough. Further, no wall surface is provided at the bottom of the cassette 10. Therefore, chemicals, bubbles, etc. can enter the cassette 10 from below the cassette 10.

The shape of the substrate 11 is not particularly limited. For example, the substrate 11 may have a rectangular shape, a square shape, a polygonal shape, a circular shape, or the like. Further, the substrate 11 may have, for example, a substantially rectangular shape, a substantially square shape, or the like in which a corner portion is cut out by a straight line or a curve. Hereinafter, an example in which the substrate 11 has a substantially rectangular shape will be described.

The length of one side of the substrate 11 can be about 100 mm to 200 mm, for example. The thickness of the substrate 11 is preferably about 200 μm or less, and more preferably about 50 μm to 200 μm. The ratio of the length of one side of the substrate 11 to the thickness of the substrate 11 ((length of one side of the substrate 11) / (thickness of the substrate 11)) is preferably 400 to 40000.

Note that the number of substrates 11 held in one cassette 10 is not particularly limited, but may be, for example, about 25 to 100. From the viewpoint of increasing the number of substrates 11 that can be set in one cassette 10, the distance L between the substrates 11 adjacent in the x-axis direction is preferably 6 mm or less, and preferably 5 mm or less. The distance L between the substrates 11 adjacent to each other in the x-axis direction is preferably 1/20 or less of the length of one side of the substrate 11, and more preferably 1/30 or less. However, if the distance L between the substrates 11 adjacent to each other in the x-axis direction is too small, there are cases where it becomes difficult to set the substrates 11 or the adjacent substrates 11 stick to each other during wet etching. Therefore, the distance L between the substrates 11 adjacent in the x-axis direction is preferably 3 mm or more, and more preferably 4 mm or more. The distance L between the substrates 11 adjacent to each other in the x-axis direction is preferably 1/42 or more of the length of one side of the substrate 11, and more preferably 1/32 or more of the length of one side of the substrate 11. .

(Processing of substrate 11)
Next, as shown in FIG. 3, a plurality of substrates 11 set in the cassette 10 and spaced apart from each other along the x-axis direction are combined with the chemical solution stored in the chemical solution tank 12 together with the cassette 10. A processing step of processing the plurality of substrates 11 is performed by dipping in the substrate 13. This processing process is an etching process or a cleaning process of the substrate 11. For example, when performing an etching process, the chemical | medical solution 13 can be used as an etching liquid. For example, when performing the cleaning process, the chemical liquid 13 can be used as the cleaning liquid.

In this processing step, the plurality of substrates 11 are immersed in the chemical solution 13 and are disposed below the plurality of substrates 11 in the chemical solution tank 12, and a plurality of bubbles in the pipes 15a to 15d constituting the bubble generating unit. Bubbles 14 (typically bubbles of inert gas such as air or nitrogen gas) are supplied from the generation ports 16 toward the plurality of substrates 11 in the chemical solution 13 to process the plurality of substrates 11.

Specifically, in the present embodiment, the processing step is performed in a state where the plurality of substrates 11 are arranged so that the plurality of bubble generating ports 16 are located in the gaps 17 between the substrates 11 adjacent in the x-axis direction in plan view. I do. For this reason, the board | substrate 11 which was partially in contact with the recessed part 10a by the bubble 14 from the bubble generation opening | mouth 16 is peeled efficiently. Therefore, the whole substrate 11 is easily in contact with the chemical solution 13 uniformly. Therefore, the plurality of substrates 11 can be processed appropriately. It is difficult for portions that are insufficiently cleaned or portions that are insufficiently etched to occur on the surfaces of the plurality of substrates 11. In addition, in the etching process for forming a concavo-convex structure called a so-called texture structure by performing anisotropic etching in the processing step, unevenness in shape and dimensional unevenness hardly occur in the formed concavo-convex structure. Accordingly, it is possible to manufacture solar cells with an improved yield rate.

From the viewpoint of more efficiently peeling the substrate 11 partially contacting the recess 10a, the diameter of the bubble generating port 16 is the distance of the gap 17 between the adjacent substrates 11 in the x-axis direction. It is preferably smaller than L, and more preferably 0.8 times or less of the distance L.

In the present embodiment, the bubbles 14 are supplied into the chemical solution 13 so that the first state and the second state are alternately generated in the processing step. Here, the first state is a state in which the amount of bubbles 14 supplied to one side of the substrate 11 in the x-axis direction is larger than the amount of bubbles 14 supplied to the other side of the substrate 11 in the x-axis direction. It is. The second state is a state in which the amount of bubbles 14 supplied to one side of the substrate 11 in the x-axis direction is smaller than the amount of bubbles 14 supplied to the other side of the substrate 11 in the x-axis direction.

Specifically, as shown in FIG. 4, a plurality of pipes 15a to 15d are arranged below the plurality of substrates 11. Each of the plurality of pipes 15 a to 15 d has a bubble generation port 16, and generates bubbles 14 from the bubble generation port 16 toward the plurality of substrates 11.

The pipes 15a to 15d each extend along the x-axis direction, which is the arrangement direction of the substrates 11. The plurality of pipes 15a to 15d are spaced apart from each other along the y-axis direction parallel to the direction in which the substrate 11 extends. The pipe 15a and the pipe 15b are arranged on the y1 side from the center of the substrate 11 in the y-axis direction. The pipe 15a is arranged outside the pipe 15b. The pipe 15c and the pipe 15d are arranged on the y2 side from the center of the substrate 11 in the y-axis direction. The pipe 15d is arranged outside the pipe 15c.

The pipes 15a to 15d are provided with a plurality of bubble generating ports 16 so as to be positioned in the gap 17 between the substrates 11. In each of the pipes 15a to 15d, a plurality of bubble generating ports 16 are provided in every other gap 17. That is, in each of the pipes 15a to 15d, a plurality of bubbles are generated so that the gap 17 where the bubble generating port 16 is located and the gap 17 where the bubble generating port 16 is not positioned alternately occur along the x-axis direction. A mouth 16 is provided.

The bubble generating ports 16 of the

pipes

15a and 15d located on the outer side and the bubble generating ports 16 of the

pipes

15b and 15c positioned on the inner side are located in different gaps 17. For this reason, the gap 17 where the bubble generating ports 16 of the

pipes

15a and 15d arranged on the outside are located and the gap 17 where the bubble generating ports 16 of the

pipes

15b and 15c arranged on the inside are located are x. They are provided alternately in the axial direction.

As shown in FIG. 5, in the first state, the amount of bubbles 14 generated from the bubble generating ports 16 of the

pipes

15a and 15d is larger than the amount of bubbles 14 generated from the bubble generating ports 16 of the

pipes

15b and 15c. On the other hand, in the second state, the amount of bubbles 14 generated from the bubble generating ports 16 of the

pipes

15a and 15d is smaller than the amount of bubbles 14 generated from the bubble generating ports 16 of the

pipes

15b and 15c. To be controlled. By controlling in this way, the amount of bubbles 14 supplied to one side of the substrate 11 in the x-axis direction is larger than the amount of bubbles 14 supplied to the other side of the substrate 11 in the x-axis direction. The state and the second state in which the amount of bubbles 14 supplied to one side of the substrate 11 in the x-axis direction is smaller than the amount of bubbles 14 supplied to the other side of the substrate 11 in the x-axis direction are alternately Arise. For this reason, the substrate 11 vibrates or swings along the x-axis direction by the bubbles 14 supplied in the first state and the bubbles supplied in the second state. Therefore, for example, it is difficult for a portion of the substrate 11 to be in contact with another substrate 11 or the cassette 10, and the entire substrate 11 is likely to be in contact with the chemical solution 13 uniformly. Therefore, the plurality of substrates 11 can be processed more suitably.

From the viewpoint of further promoting the vibration and swinging of the substrate 11, in the first state, the bubbles 14 are supplied to one side of the substrate 11 in the x-axis direction, while the bubbles 14 are supplied to the other side of the substrate 11 in the x-axis direction. In the second state, it is preferable not to supply the bubbles 14 to one side of the substrate 11 in the x-axis direction while supplying the bubbles 14 to the other side of the substrate 11 in the x-axis direction. Further, the supply position of the bubbles 14 on one side of the substrate 11 in the x-axis direction and the supply position of the bubbles 14 on the other side of the substrate 11 in the x-axis direction are mutually in the y-axis direction, which is the direction in which the substrate 11 extends. Preferably they are different. In addition, since the recesses 10a are provided so that the interval becomes wider toward the inside, vibration and swinging of the substrate 11 are further promoted.

For example, when the thickness of the substrate 11 is as thin as 200 μm or less, the substrate 11 is easily bent. Therefore, the adjacent substrates 11 may come into contact with each other, and it may be difficult to suitably supply the chemical solution to the contact portion of the substrate 11. Similarly, when the distance between adjacent substrates 11 is 1/20 or less of the length of one side when the planar shape of the substrate 11 is approximated to a rectangle, and further 1/30 or less, The board | substrates 11 which come in contact may contact, and it may become difficult to supply a chemical | medical solution to the contact part of the board | substrate 11 suitably. Therefore, the technique of this embodiment is particularly useful.

In the first embodiment, two

pipes

15a and 15d for supplying bubbles 14 to one side of the substrate 11 and two

pipes

15b and 15c for supplying bubbles 14 to the other side of the substrate 11 are provided. Explained. However, the present invention is not limited to this configuration. For example, as shown in FIG. 6, one pipe 15 a for supplying bubbles 14 to one side of the substrate 11 and one pipe 15 c for supplying bubbles 14 to the other side of the substrate 11 may be provided.

Further, as shown in FIG. 7, the bubble generating ports 16 of the pipes 15 a to 15 d may be positioned in all the gaps 17.

DESCRIPTION OF SYMBOLS 10 ... Cassette 10a ... Recess 11 ... Board | substrate 12 ... Chemical solution tank 13 ... Chemical solution 14 ... Bubble 15a-15d ... Pipe (bubble generation part)
16 ... Bubble generating port 17 ... Gap

Claims

A method of manufacturing a solar cell having a substrate made of a semiconductor material,
A plurality of the substrates arranged along one direction are immersed in a chemical solution stored in a chemical solution tank, and from a plurality of bubble generation ports of a bubble generation unit arranged below the plurality of substrates in the chemical solution tank. A treatment step of processing the plurality of substrates by supplying bubbles toward the plurality of substrates in the chemical solution;
A method of manufacturing a solar cell, wherein the processing step is performed in a state in which the plurality of substrates are arranged so that the bubble generating port is positioned between the substrates adjacent in the one direction in plan view.
The method for manufacturing a solar cell according to claim 1, wherein a diameter of the bubble generating port is smaller than a gap distance between the substrates adjacent in the one direction.
The plurality of substrates are arranged so that an interval between the adjacent substrates is 1/20 or less of a length of one side when the planar shape of the substrate is approximated to a rectangle. A method for manufacturing a solar cell.
4. The method for manufacturing a solar cell according to claim 1, wherein the thickness of the substrate is 200 μm or less.
As the processing step,
A cleaning step of cleaning the substrate by immersing it in a cleaning solution;
An etching step of etching by immersing the substrate in an etchant;
The method for manufacturing a solar cell according to any one of claims 1 to 4, wherein at least one of the steps is performed.