KR101482130B1 - Manufacturing Method For Back Contact of Solar Cell And The Same Thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a rear electrode solar cell and a rear electrode solar cell obtained by the method, wherein the process of forming an emitter and a BSF (Back Surface Field) is reduced. A back surface field (BSF) is formed on the rear surface of the substrate, an n + layer is formed on the front surface of the substrate, an emitter and a back surface field (BSF) And forming a patterned metal electrode layer on the contact openings on the rear surface of the substrate. The present invention also relates to a method of manufacturing a rear electrode solar cell.

Rear electrode solar cell, emitter, BSF, contact openings

Description

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to a method of manufacturing a back electrode solar cell,

The present invention relates to a method of manufacturing a back electrode solar cell that reduces the process cost by reducing emitter and BSF (Back Surface Field) forming processes. The present invention relates to a rear electrode solar cell manufactured by the above method, and a silicon oxide layer and a PECVD SiNx: H layer deposited sequentially on the entire surface of the substrate are formed, a substrate on which an emitter and a BSF (Back Surface Field) And a rear electrode solar cell including a plurality of solar cells, in which a silicon oxide layer, a PECVD SiO ₂ layer, and a metal electrode layer are sequentially deposited on the rear surface.

With the recent depletion of existing energy resources such as oil and coal, interest in alternative energy to replace them is increasing. Among them, solar cells are attracting particular attention because they are rich in energy resources and have no problems with environmental pollution. Solar cells include solar cells that generate the steam needed to rotate the turbine using solar heat, and solar cells that convert sunlight into electrical energy using the properties of semiconductors. Generally, a solar cell is a solar cell.

The solar cell has a junction structure of a p-type semiconductor and an n-type semiconductor. When light enters the solar cell, electrons and electrons (-) charged by (+) electrons escape by interaction with light and the material constituting the semiconductor of the solar cell, So that current flows. That is, the electrons are attracted toward the n-type semiconductor, and the holes are attracted toward the p-type semiconductor to move to the n-type electrode and the p-type electrode bonded to the n-type semiconductor and the p-type semiconductor, respectively. When the electrodes are connected by a wire, electric power is obtained because electric power flows.

Among the above-described solar cells, the rear electrode solar cell has a higher light receiving rate than the front electrode and can reduce the series resistance at the same time by disposing the cathode, the anode electrode, and the wiring on the rear surface, unlike the conventional solar cell . Also, the module is easy to manufacture, and research is actively underway.

BACKGROUND ART In order for a back-surface solar cell to be widely used in various industrial fields, it is necessary to develop a method of manufacturing a back-surface electrode solar cell that simplifies a manufacturing process and reduces manufacturing costs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a back electrode solar cell in which a manufacturing process is simplified and a manufacturing cost is reduced in a back electrode solar cell.

In particular, it is an object of the present invention to provide a method of manufacturing a back electrode solar cell in which an emitter and a back surface field (BSF) are formed by only one high-temperature diffusion process, And a method for producing the same.

According to an aspect of the present invention, there is provided a method of fabricating a thin film solar cell including forming an emitter and a back surface field (BSF) on a rear surface of a substrate, forming an n + Forming an array of contact openings in an emitter and a back surface field (BSF) on the backside of the substrate, and forming a patterned metal electrode layer in the contact openings on the backside of the substrate.

The step of forming the emitter and BSF may include forming a p-type doping precursor film, a patterned diffusion preventing film, and an n-type doping precursor film on the back surface of the substrate in this order, Lt; / RTI > Forming a p-type doping precursor film on the rear surface of the substrate; forming a patterned diffusion prevention film on the p-type doping precursor film; forming a p-type doping precursor film so that a part of the front surface of the diffusion- Forming a n-type doping precursor film on a rear surface and a side surface of the diffusion preventing film, and performing a high-temperature diffusion process; and a step of forming a diffusion preventing film on the BSG layer, the PSG layer, And then etching the substrate.

The step of forming the n + layer on the entire surface of the substrate may include forming a diffusion prevention layer on the back surface of the substrate having the emitter and the BSF formed thereon, Forming an n-type precursor film on the entire surface of the anisotropically etched substrate, and performing a high-temperature diffusion process; and etching the PSG layer and the diffusion barrier layer formed by the high-temperature diffusion process can do.

The step of forming a contact opening arrangement in an emitter and a back surface field of the substrate may include forming a front surface of the substrate on which the n + layer is formed, an emitter and a BSF (Back Surface Field) forming a silicon oxide layer on the back side of the substrate, PECVD SiNx on the silicon oxide layer of the substrate surface: at the same time to form an H layer, forming a PECVD SiO ₂ layer on the substrate back and side and the silicon of the PECVD SiO ₂ layer And etching the oxide layer.

The forming of the patterned metal electrode layer on the contact opening on the rear surface of the substrate may include performing screen printing of the metal paste on the PECVD SiO ₂ layer and the contact opening on the rear surface of the substrate.

The manufacturing method of the rear electrode solar cell of the present invention can simplify the emitter and BSF formation process compared with the conventional method and can increase the cost saving effect in terms of the production cost, A simpler process can provide a back electrode solar cell.

An emitter and a BSF (Back Surface Field) are formed from a p-type doping precursor film and an n-type doping precursor film through a single high-temperature diffusion process to simplify the manufacturing process of the back electrode solar cell The cost can be reduced.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same or similar components, and the same reference numerals will be used to designate the same or similar components. Detailed descriptions of known functions and configurations are omitted.

FIG. 1 is a cross-sectional view of a stacked structure of a device showing a method of manufacturing a back electrode solar cell according to an embodiment of the present invention in the order of steps. The following process steps are only one embodiment and may not necessarily be limited to this order.

Referring to FIG. 1, a brief description will be given below.

First, an emitter 105 and a BSF (Back Surface Field) 106 are formed on the rear surface of the substrate 101 (FIG. 1A), an n + layer 109 is formed on the entire surface of the substrate A patterned metal electrode layer 114 is formed on the contact opening 113 on the backside of the substrate by forming an array of contact holes 113 in the back emitter 105 and the BSF 106 (FIG. 1D), the rear electrode solar cell of the present invention can be manufactured.

The substrate 101 may be an n-type single crystal silicon (Si) substrate or a p-type single crystal silicon (Si) substrate.

The formation of the contact hole may be accomplished using conventional, well-known etch processes generally known to those skilled in the art. Any one of an optical scribing method, a mechanical scribing method, a plasma using etching method, a wet etching method, a dry etching method, a lift-off method, and a wire mask method can be selected.

On the other hand, a laser scribing method is mainly used as an optical scribing method, and a laser scribing method is a method of scanning a thin film on a substrate by scanning pulsed laser light relative to the substrate.

The manufacturing method of the solar cell according to the present invention will now be described in detail with reference to the drawings.

FIG. 2 is a cross-sectional view of a rear electrode solar cell structure showing steps of forming a p.sup. + Region and an n.sup. + Region on a rear surface of a substrate in a process order.

The substrate 101 is prepared as shown in FIG. 2A, and a process for forming the p-type doped precursor film 102 on the back surface of the substrate 101 is performed as shown in FIG. 2B. An n-type single crystal silicon (Si) substrate was used as the substrate.

The p-type doped precursor film 102 can be formed by spray coating Boron Spin On Dopant (B-SOD) on the back surface of the substrate 101 and then drying it. On the other hand, instead of using the B-SOD, boron doped SiO ₂ may be used. That is, boron doped SiO ₂ may be PECVD deposited on the back surface of the substrate 101 to form the p-type doped precursor film 102.

Plasma Enhanced Chemical Vapor Deposition (PECVD) is a method of depositing a thin film by using a reaction in which electrons having a high energy by electrons collide with gas molecules in a neutral state to decompose the gas molecules and attach the decomposed gas atoms to the substrate Chemical Vapor Deposition (CVD) refers to chemical vapor deposition (CVD).

In the above embodiment, B (boron) is used to form a p-type doped precursor film, but not only B but also Ga (gallium) or Al (aluminum) can be used. Although the p-type doped precursor film is formed by spray coating and drying in the above embodiment, spin coating or screen printing followed by drying may be used, or a chemical vapor deposition method Vapor Deposition (CVD), or physical vapor deposition (PVD) may be used.

Next, as shown in FIG. 2C, a step of forming a patterned diffusion prevention film 103 on the p-type doped precursor film 102 is performed. The diffusion barrier layer 103 is formed by screen printing a paste on an area where an emitter is to be formed, and drying and firing the paste.

The diffusion barrier film has an etching selection ratio as compared with the p-type doping precursor film, and functions to prevent thermal diffusion of impurities. In addition, the emitter functions to collect holes.

Next, as shown in FIG. 2D, the diffusion preventing film 103 is formed as a hard mask, and a p-type doping precursor film (not shown) is formed to expose a part of the front surface of the diffusion preventing film 103 and a part of the rear surface of the substrate 101 102 are etched. Through such a process, a gap of several to several tens of micrometers can be formed between the p-type doping precursor film 102 and the n-type doping precursor film 104 to be formed in the following step. As a result, it is possible to prevent the butting between the emitter 105 formed from the p-type doping precursor film 102 and the back surface field 106 formed from the n-type doping precursor film 104 .

Next, as shown in FIG. 2E, a step of forming an n-type doping precursor film 104 on the rear surface and side surfaces of the diffusion preventing film 103 and the back surface of the substrate 101 is performed.

The n-type doping precursor film 104 may be formed by spray coating a phosphorus spin on dopant (P-SOD) on the rear surface and side surfaces of the diffusion prevention film 103 and the rear surface of the substrate 101, have. On the other hand, it is also possible to use a SiO ₂ (posphorous doped SiO ₂₎ doped with phosphorus in place of using the P-SOD. That is, the doped SiO ₂ (posphorous doped SiO _2), the substrate 101 on the rear and sides and the substrate 101 to the rear rear spray-coated (spray coating) with, n-type to form a doping precursor film 104 have.

Although P (phosphorus) is used to form the n-type doping precursor film in the above embodiment, elements such as As (arsenic) or Sb (antimony) as well as P can be used. Although the n-type doping precursor film is formed by spray coating and drying in this embodiment, spin coating or screen printing followed by drying may be used, or a chemical vapor deposition method (Chemical Vapor Deposition Vapor Deposition (CVD), or physical vapor deposition (PVD) may be used.

Next, a high temperature diffusion process is performed using a diffusion furnace or a belt furnace. The B-SOD of the p-type doped precursor film 102 is transformed into borosilicate glass (BSG) and the P-SOD of the n-type doped precursor film 104 is transformed into a phosphorous- Silicate Glass) and patterned diffusion is possible at the same time. 2F, an emitter 105 and a BSF (Back Surface Field) 106 are alternately formed on the back surface of the substrate 101. The BSG layer, the PSG layer, and the diffusion barrier layer 103 are etched, .

Next, FIG. 3 is a cross-sectional view of the rear electrode solar cell structure showing the step of forming an n + layer on the entire surface of the substrate in a process order.

3A, the process of screen-printing the diffusion prevention film 107 on the rear surface of the substrate 101 on which the emitter 105 and the BSF 106 are formed is performed.

3B, a solution of NaOH, KOH, TMAH (tetramethylammonium hydroxide) or the like is used to etch the entire surface of the substrate 101 anisotropically. Then, a random pyramid texture texturing

Next, as shown in FIG. 3C, CVD (Chemical Vapor Deposition) is performed on the entire surface of the anisotropically etched substrate 101 and P-SOD is performed to dry the n-type precursor film 108 ) Is formed. On the other hand, it is also possible to use a SiO ₂ (posphorous doped SiO ₂₎ doped with phosphorus in place of using the P-SOD. That is, in forming a doped SiO ₂ (posphorous doped SiO ₂₎ the substrate 101 by executing the (Chemical Vapor Deposition), CVD on the back of the back and sides and the substrate 101 to the back, n-type doped precursor film 104 You may.

Next, a high temperature diffusion process is performed using a diffusion furnace or a belt furnace. As shown in FIG. 3D, the n + layer 109 is formed on the entire surface of the substrate 101 by etching the PSG layer and the diffusion barrier layer 107 formed through the high-temperature diffusion process.

4 is a cross-sectional view of the back electrode solar cell structure illustrating the steps of forming the contact opening arrangement in the emitter and BSF on the backside of the substrate in the order of the process.

First, after the substrate having undergone the above-described steps is cleaned, a high-temperature heat treatment is carried out by diffusion in an oxygen atmosphere or in a belt furnace. In this process, as shown in FIG. 4A, a silicon oxide layer 110 is simultaneously formed on the back surface of the substrate and the n + layer on the front surface of the substrate. The silicon oxide layer 110 is a layer that protects the surface of the substrate and is formed to have a thickness of several tens to several hundreds of nm.

Then, as shown in FIG. 4B, a PECVD SiO ₂ layer 111 is formed on the rear surface of the substrate, and a PECVD SiNx: H layer 112 is formed on the silicon oxide layer on the entire surface of the substrate. The PECVD SiO ₂ layer 111 is intended to enhance the insulating property of the rear surface of the substrate. In addition, the PECVD SiNx: H layer 112 is an anti-reflection coating (ARC) film for reducing the reflection phenomenon on the entire substrate.

Next, as shown in FIG. 4C, a process of etching the side surfaces of the PECVD SiO ₂ layer 111 and the silicon oxide layer 110 is performed to form an array of contact openings 113.

Finally, a metal paste is screen printed on the PECVD SiO ₂ (111) layer on the backside of the substrate 101 and the contact openings 113 through the above-described processes to form a patterned metal electrode layer 114 . That is, the metal electrode layer 114 is connected to each of the emitters 105 and the back surface field (BSF) 106, thereby completing the fabrication of the rear electrode solar cell composed of a plurality of cells.

In other words, the rear electrode solar cell manufactured in one embodiment of the present invention is composed of a plurality of solar cell units. A silicon oxide layer 110 and a PECVD SiO ₂ layer 112 are sequentially formed on the entire surface of the substrate 101. A silicon oxide layer 110, A layer 111 and a metal electrode layer 114 are sequentially formed.

Although the present invention has been described in connection with the specific embodiments of the present invention, it is to be understood that the present invention is not limited thereto. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. In addition, the materials of each component described herein can be readily selected and substituted for various materials known to those skilled in the art. Those skilled in the art will also appreciate that some of the components described herein can be omitted without degrading performance or adding components to improve performance. In addition, those skilled in the art may change the order of the method steps described herein depending on the process environment or equipment. Therefore, the scope of the present invention should be determined by the appended claims and equivalents thereof, not by the embodiments described.

FIG. 1 is a cross-sectional view of a rear electrode solar cell structure schematically showing a manufacturing method of a rear electrode solar cell according to an embodiment of the present invention, according to process steps.

FIG. 2 is a cross-sectional view illustrating a back electrode solar cell structure in which emitter and BSF (Back Surface Field) are sequentially formed on a rear surface of a substrate in the process of manufacturing a rear electrode solar cell according to an embodiment of the present invention. Fig.

FIG. 3 is a cross-sectional view of a rear electrode solar cell structure showing a step of forming an n + layer on a front surface of a substrate in the process of manufacturing a rear electrode solar cell according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a step of forming a contact opening array in an emitter and a back surface field (BSF) on the rear surface of a substrate in the process of manufacturing a back electrode solar cell according to an embodiment of the present invention. Sectional view of an electrode solar cell structure.

FIG. 5 illustrates a process of fabricating a back electrode solar cell according to an exemplary embodiment of the present invention. Referring to FIG. 5, a step of forming a patterned metal electrode layer in a contact opening on a rear surface of a substrate is performed by using a back electrode solar cell structure Sectional view.

DESCRIPTION OF THE REFERENCE NUMERALS OF THE DRAWINGS FIG.

101: substrate

102: p-type doping precursor film

103, 107: diffusion barrier film

104, 108: n-type doping precursor film

105: emitter

106: BSF (Back Surface Field)

109: n + layer

110: silicon oxide layer

111: PECVD SiO ₂ layer

112: PECVD SiNx: H layer

Claims (8)

Forming an emitter and a back surface field (BSF) on the rear surface of the substrate; Forming an n + layer over the entire surface of the substrate; Forming an array of contact openings in an emitter and a back surface field (BSF) on the backside of the substrate; And And forming a patterned metal electrode layer on the contact opening on the rear surface of the substrate. The method of claim 1, wherein forming the emitter and the back surface field (BSF) Wherein a p-type doping precursor film, a patterned diffusion preventing film, and an n-type doping precursor film are sequentially formed on a rear surface of the substrate, and then a high thermal diffusion process is performed. The method of claim 1, wherein forming the emitter and the back surface field (BSF) Forming a p-type doped precursor film on a rear surface of the substrate; Forming a patterned diffusion barrier layer on the p-type doped precursor layer; Etching the p-type doping precursor film such that a part of the front surface of the diffusion preventing film and a part of the rear surface of the substrate are exposed; Forming an n-type doping precursor film on a rear surface and a side surface of the diffusion prevention film and a rear surface of the substrate, and performing a high-temperature diffusion process; And And etching the BSG layer, the PSG layer, and the diffusion prevention layer formed by the high-temperature diffusion process. 2. The method of claim 1, wherein forming the n + Forming a diffusion barrier layer on the back surface of the substrate on which the emitter and BSF are formed; Etching the entire surface of the substrate anisotropically after forming the diffusion barrier layer; Forming an n-type precursor film on the entire surface of the anisotropically etched substrate, and performing a high-temperature diffusion process; And etching the PSG layer and the diffusion prevention layer formed by the high-temperature diffusion process. 2. The method of claim 1, wherein forming a contact opening array in an emitter and a back surface field (BSF) Forming a silicon oxide layer on a front surface of the substrate on which the n + layer is formed and on a back surface of a substrate on which an emitter and a BSF (Back Surface Field) are formed; Forming a PECVD SiNx: H layer on the silicon oxide layer on the entire surface of the substrate, and forming a PECVD SiO ₂ layer on the rear surface of the substrate; And And etching the side surface of the PECVD SiO ₂ layer and the silicon oxide layer. The method of claim 1, wherein forming the patterned metal electrode layer in the contact opening on the backside of the substrate comprises: And performing a screen printing of the metal paste on the PECVD SiO ₂ layer and the contact opening on the rear surface of the substrate. A silicon oxide layer and a PECVD SiNx: H layer sequentially formed on the entire surface of the substrate are formed, A rear electrode solar cell comprising a plurality of solar cells, wherein a silicon oxide layer, a PECVD SiO ₂ layer, and a metal electrode layer are sequentially deposited on a rear surface of a substrate on which an emitter and a BSF (Back Surface Field) are formed. 8. The method of claim 7, The metal electrode layer is back-contact solar cells, characterized in that extending from the back of the PECVD SiO ₂ layer is formed to surround the side surfaces and the side surface of the silicon oxide layer of PECVD SiO ₂ layer.

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