KR20080062515A - Method of preparing solar cell and solar cell prepared by the same - Google Patents

Abstract

A method for manufacturing a solar cell and the solar cell manufactured with the same are provided to simplify a manufacturing process of the solar cell by performing an organic matter removal and a saw damage removal of a silicon substrate in an as-cut state in one process only. A silicon substrate of the first conductive type is processed with a pre-process solution to remove an organic matter on the silicon substrate and a crack formed on the silicon substrate. The pre-process solution includes sulphuric acid, peracid, hydrofluoric acid, nitric acid, and water. A conductive layer(203a) of the second conductive type having a conductive type opposite to the silicon substrate, is formed on the silicon substrate. An anti-reflective layer(205) is formed on the conductive layer of the second conductive type. A front electrode(207) is formed to pass through the anti-reflective layer and connected to the conductive layer of the second conductive type. A rear electrode(209) is formed on a surface opposite to a surface where the anti-reflective layer of the silicon substrate is formed.

Description

Method for preparing solar cell and solar cell manufactured using same {Method of preparing solar cell and solar cell prepared by the same}

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.

1 is a schematic diagram showing the basic structure of a solar cell.

2a to 2c are views for explaining the solar cell manufacturing method of the present invention.

The present invention relates to a method for manufacturing a solar cell and a solar cell manufactured using the same, and more particularly, to a method for manufacturing a solar cell having shortened processing time and improved work convenience and productivity by simplifying the process, and using the same. It relates to a solar cell produced.

Recently, as the prediction of depletion of existing energy resources such as oil and coal is expected, interest in alternative energy to replace them is increasing. Among them, solar cells are particularly attracting attention because they are rich in energy resources and have no problems with environmental pollution. Solar cells include solar cells that generate steam for rotating turbines using solar heat, and solar cells that convert photons into electrical energy using the properties of semiconductors. Refers to photovoltaic cells (hereinafter referred to as solar cells).

Referring to FIG. 1 showing the basic structure of a solar cell, a solar cell has a junction structure of a p-type semiconductor 101 and an n-type semiconductor 102 like a diode, and when light is incident on the solar cell, Interaction with the materials that make up the semiconductor causes electrons with negative charge and electrons to escape, creating holes with positive charge, and as they move, current flows. This is called a photovoltaic effect. Among the p-type 101 and n-type semiconductors 102 constituting the solar cell, electrons are directed toward the n-type semiconductor 102 and holes are p-type semiconductors ( Pulled toward 101 and moved to the electrodes 103 and 104 bonded to the n-type semiconductor 101 and the p-type semiconductor 102, respectively, and when the electrodes 103 and 104 are connected by wires, electricity flows. Can get

Such a solar cell can be manufactured by forming a conductive layer of a different conductivity type on a semiconductor substrate, and forming an anti-reflection film and a front electrode and a back electrode. However, before this process, since the organic substrate is buried or cracked in the as-cut semiconductor substrate, the organic material removal process and the saw d amage removal process for removing the crack and It must go through the same pretreatment process. However, these processes are essential to improve the performance of the solar cell, but the process takes a long time, there is a need to simplify the process and shorten the process time to improve productivity and convenience of operation.

The present invention has been made to solve the above-mentioned problems of the prior art, the technical problem to be achieved in the present invention is to improve the productivity and convenience of work by simplifying the manufacturing process of the solar cell, achieving the technical problem It is an object of the present invention to provide a method for manufacturing a solar cell and a solar cell manufactured using the same.

In order to achieve the technical problem to be achieved by the present invention, the present invention, (S1) by treating the first conductivity-type silicon substrate with a pretreatment solution containing sulfuric acid, peracid, hydrofluoric acid, nitric acid and water and buried in the silicon substrate and Removing cracks formed in the silicon substrate; (S2) forming a second conductivity type conductive layer opposite to the silicon substrate on the silicon substrate; (S3) forming an anti-reflection film on the second conductivity type conductive layer; (S4) forming a front electrode to penetrate the anti-reflection film and to be connected to the second conductive type conductive layer; (S5) providing a solar cell manufacturing method comprising the step of forming a back electrode on the surface opposite to the surface on which the anti-reflection film of the silicon substrate is formed.

In the method of manufacturing the solar cell, the content of each component in the pretreatment solution is 5 to 7 parts by weight sulfuric acid, 9 to 15 parts by weight peracid, 15 to 30 parts by weight hydrofluoric acid, 15 parts by weight nitric acid based on 100 parts by weight water. It is preferable that it is 40 weight part.

The antireflection film may be typically formed of silicon nitride, and the formation of the antireflection film is typically performed by a method selected from the group consisting of plasma chemical vapor deposition (PECVD), chemical vapor deposition (CVD) and sputtering. Can be.

The step (S4) may be performed by applying the front electrode forming paste on the antireflection film according to a predetermined pattern and then heat-treating, and the step (S5) the back electrode forming paste is formed on the silicon substrate. It can be carried out by applying heat to the surface opposite to the surface.

The present invention also, 100 parts by weight of water; Sulfuric acid 5 to 7 parts by weight; 9-15 parts by weight of peracid; 15 to 30 parts by weight of hydrofluoric acid; And 15 to 40 parts by weight of nitric acid; provides a pre-treatment solution of a silicon wafer for solar cells comprising a.

The present invention also provides a solar cell manufactured using the solar cell manufacturing method of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings to assist in understanding the present invention.

According to the manufacturing method of the solar cell of the present invention, first, the organic matter buried in the first conductivity type silicon substrate and the cracks formed on the silicon substrate are removed. In the present invention, by treating the silicon substrate with a pretreatment solution containing sulfuric acid, peric acid, hydrofluoric acid, nitric acid and water can be performed through one process to improve the productivity and convenience of work, using only conventional nitric acid, hydrofluoric acid and water Since sulfuric acid enters more than the crack removal process performed, it is possible to improve the process efficiency and shorten the process time by increasing the temperature of the entire solution due to decomposition and heating of sulfuric acid.

In the pretreatment solution, the composition ratio of each component is preferably 5 to 7 parts by weight of sulfuric acid, 9 to 15 parts by weight of peracid, 15 to 30 parts by weight of hydrofluoric acid, and 15 to 40 parts by weight of nitric acid with respect to 100 parts by weight of water. If the composition ratio of sulfuric acid exceeds the upper limit, excessive amount of etching occurs due to excessive temperature rise, and if it is less than the lower limit, it is not preferable because the organic matter removing process is not sufficient, and the composition ratio of peracid exceeds the upper limit. If the addition of peracid causes waste of the solution and falls below the lower limit, it is not preferable because it is not sufficient for the organic material removal process. If the composition ratio of hydrofluoric acid exceeds the upper limit, too much fine wrinkles are formed on the wafer surface, which adversely affects the efficiency. It is not possible to etch due to excessive hydrofluoric acid, and it is not preferable because the etching is not good when it falls below the lower limit, and when the composition ratio of nitric acid exceeds the upper limit, the etching is difficult due to excessive oxidation of the wafer and the wafer is lower than the lower limit. Significantly reduced oxidizing power, Not undesirable.

Next, second conductive semiconductor layers 203a and 203b of opposite conductivity type to the substrate are formed on the semiconductor substrate subjected to the pretreatment (see FIG. 2A). As a result, a p-n junction is formed at an interface between the first conductive type conductive layer 201 and the second conductive type conductive layers 203a and 203b in the semiconductor substrate. As the semiconductor substrate, both p-type and n-type may be used, and among them, p-type silicon substrate may be most preferably used because of the long life and mobility of the minority carrier (the electron is the minority carrier in the p-type). have. The p-type silicon substrate is typically doped with group III elements such as B, Ga, and In, and the n-type conductive layer is formed by doping the p-type silicon substrate with group 5 elements such as P, As, and Sb. A junction can be formed.

The second conductive conductive layers 203a and 203b and the pn junction forming step may be performed in various ways. Typically, the semiconductor substrate may be placed in a diffusion path to form the second conductive semiconductor layers 203a and 203b. There is a method of heating a diffusion furnace after injecting a gas containing a dopant, and a method of applying a composition containing a dopant to one surface of a semiconductor substrate and placing it in the diffusion furnace and heating it. In the former method, since the second conductive type conductive layers 203a and 203b are formed on the entire surface of the semiconductor substrate, an edge isolation process of cutting off side edges of the silicon wafer is performed. This can prevent the electrical connection between the front electrode and the rear electrode. FIG. 2A is a diagram schematically showing the shape of the semiconductor substrate after forming the second conductivity type conductive layers 203a and 203b by the former method and undergoing an edge isolation process.

Next, an anti-reflection film is formed on the second conductive conductive layer 203a formed on the semiconductor substrate (see FIG. 2B). The second conductive conductive layers 203a and 203b are formed on both surfaces of the semiconductor substrate in the forming process. When the conductive conductive layers 203a and 203b are formed, one of the second conductive conductive layers 203a may be selected to form an antireflection film. The anti-reflection film 205 is formed to lower the reflectance to sunlight, and may be typically including silicon nitride, and is typically referred to as plasma chemical vapor deposition (PECVD), chemical vapor deposition (CVD) and sputtering. It may be formed by a method selected from the group consisting of.

Finally, the front electrode 207 is formed to penetrate the anti-reflection film 205 and be connected to the second conductivity-type semiconductor layer 203a, and on the surface opposite to the surface on which the anti-reflection film 205 of the silicon substrate is formed. A back electrode 209 is formed (see FIG. 2C). The order of forming the front electrode 207 and the back electrode 209 is not limited, and any electrode may be formed first. The front electrode 207 may be formed by applying a front electrode forming paste on an antireflection film in accordance with a predetermined pattern and then heat treating the front electrode 207 through the antireflection film 205 through heat treatment. It is connected to the type semiconductor layer 203a (punch through). The back electrode 209 may be formed by applying a back electrode forming paste to a surface opposite to a surface on which the anti-reflection film 205 of the silicon substrate is formed, and then heat-treating the semiconductor substrate. The electrode forming material is doped to a predetermined depth from the contacting surface to form a back surface field (211). Even when the second conductive conductive layers 203a and 203b are formed on both surfaces of the semiconductor substrate in the process of forming the second conductive conductive layers 203a and 203b, the conductivity of the second conductive conductive layer 203b on the rear surface is also applied. The mold is changed to form the BSF layer 211. The steps (S4) and (S5) may be performed by applying a front electrode forming paste and a back electrode forming paste, respectively, followed by heat treatment at the same time.

A silver electrode is typically used as the front electrode 207 because the silver electrode has excellent electrical conductivity, and an aluminum electrode is typically used as the back electrode 209, which not only has excellent conductivity but also silicon. Because of good affinity with the bond is good. In addition, the aluminum electrode can increase efficiency by forming a p + layer, that is, a BSF layer 211, on the silicon substrate when the p-type silicon substrate is used as a trivalent element so that carriers can be collected without disappearing from the surface.

The terms or words used in this specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors can appropriately define the concept of terms in order to best describe their invention. Based on the principle, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

In addition, the embodiments described herein are only the most preferred embodiments of the present invention and do not represent all of the technical idea of the present invention, and various equivalents and modifications that may substitute them at the time of the present application are provided. It should be understood that there may be.

According to the solar cell manufacturing method of the present invention, by removing the organic matter and saw damage removal of the silicon substrate in the s-cut state in a single process to simplify the process, it is possible to improve the productivity and convenience of solar cell manufacturing have.

Claims (10)

(S1) treating the first conductive silicon substrate with a pretreatment solution containing sulfuric acid, peracid, hydrofluoric acid, nitric acid, and water to remove organic matter on the silicon substrate and cracks formed on the silicon substrate; (S2) forming a second conductivity type conductive layer opposite to the silicon substrate on the silicon substrate; (S3) forming an anti-reflection film on the second conductivity type conductive layer; (S4) forming a front electrode to penetrate the anti-reflection film and to be connected to the second conductive type conductive layer; (S5) forming a rear electrode on a surface opposite to the surface on which the anti-reflection film of the silicon substrate is formed. The method of claim 1, The content of each component in the pretreatment solution is 5 to 7 parts by weight of sulfuric acid, 9 to 15 parts by weight of peracid, 15 to 30 parts by weight of hydrofluoric acid, 15 to 40 parts by weight of nitric acid, based on 100 parts by weight of water. Manufacturing method. The method of claim 1, The silicon substrate is a manufacturing method of a solar cell, characterized in that the p-type silicon substrate. The method of claim 1, The anti-reflection film is a solar cell manufacturing method characterized in that it comprises a silicon nitride. The method of claim 1, The step (S3) is a manufacturing method of a solar cell, characterized in that carried out by a method selected from the group consisting of plasma chemical vapor deposition (PECVD), chemical vapor deposition (CVD) and sputtering. The method of claim 1, The step (S4) is a method of manufacturing a solar cell, characterized in that the front electrode forming paste is applied on the antireflection film according to a predetermined pattern, followed by heat treatment. The method of claim 1, The step (S5) is a method for manufacturing a solar cell, characterized in that the back electrode forming paste is applied to the surface opposite to the surface on which the anti-reflection film of the silicon substrate is formed, followed by heat treatment. The method of claim 1, In the steps (S4) and (S5), the front electrode forming paste is coated on the antireflection film according to a predetermined pattern, and the back electrode forming paste is applied on the opposite side to the surface on which the antireflection film of the silicon substrate is formed. The solar cell manufacturing method characterized in that carried out by the heat treatment at the same time. 100 parts by weight of water; Sulfuric acid 5 to 7 parts by weight; 9-15 parts by weight of peracid; 15 to 30 parts by weight of hydrofluoric acid; And 15 to 40 parts by weight of nitric acid; a pretreatment solution of a silicon wafer for a solar cell comprising a. The solar cell manufactured using the manufacturing method of the solar cell of any one of Claims 1-8.

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