KR100972780B1 - Solar cell and manufacturing method - Google Patents

Abstract

Disclosed is a method of manufacturing a thin film silicon solar cell. The solar cell manufacturing method according to the present invention comprises the steps of (a) forming a first electrode layer 120 on the substrate 100; (b) forming a first amorphous silicon layer 130 on the first electrode layer 120; (c) forming a second amorphous silicon layer 140 on the first amorphous silicon layer 130; (d) forming a third amorphous silicon layer 150 on the second amorphous silicon layer 140; (e) crystallizing the first to third amorphous silicon layers 130, 140 and 150 to form the first to third crystalline silicon layers 135, 145 and 155; (f) etching the first to third crystalline silicon layers 135, 145 and 155 to form a plurality of unit cells; (g) etching the first to third crystalline silicon layers 135, 145 and 156 to form a first contact hole 160 exposing the first electrode layer 122; (h) forming a mask layer 170; (i) etching the mask layer 170 to form a second contact hole 180 exposing the third crystalline silicon layer 155; And (j) forming the second electrode layer 190.

Solar cell, silicon, crystalline silicon, series connection, metal, metal silicide

Description

Solar cell and method for manufacturing the same {Solar Cell And Method For Manufacturing The Same}

 The present invention relates to a thin film silicon solar cell and a method of manufacturing the same. More specifically, the present invention relates to a solar cell and a method of manufacturing the same, wherein a metal silicide layer is applied as an electrode layer connected to an n-type silicon layer when the plurality of unit cells constituting the solar cell are connected in series.

Solar cells are a key component of solar power, which converts sunlight directly into electricity, and its application ranges from space to home.

A solar cell is basically a diode composed of a pn junction and its operation principle is as follows. When solar light having energy greater than the energy band gap of a semiconductor is incident on a pn junction of a solar cell, electron-hole pairs are generated, and electrons are n-layers and holes are p-layers by an electric field formed at the pn junction. As it moves, photovoltaic power is generated between pn. At this time, if a load or a system is connected to both ends of the solar cell, current flows to produce power.

Solar cells are variously classified according to materials used as light absorbing layers, and silicon-based solar cells using silicon as light absorbing layers are typical. Silicon-based solar cells are classified into substrate type (single crystal, poly crystal) solar cells and thin film type (amorphous, poly crystal) solar cells. Other types of solar cells include CdTe and CIS (CuInSe ₂ ) compound thin film solar cells, III-V solar cells, dye-sensitized solar cells, organic solar cells, and the like.

The single crystal silicon substrate type solar cell has an advantage of significantly higher conversion efficiency than other types of solar cells, but has a fatal disadvantage of high manufacturing cost by using a single crystal silicon wafer. The polycrystalline silicon substrate type solar cell may also be cheaper to manufacture than the monocrystalline silicon type substrate solar cell. However, since the solar cell is made from bulk raw materials, the cost of raw materials is high and the process itself is expensive. Due to the complexity, there is a limit in manufacturing cost reduction.

In order to solve the problems of the substrate-type solar cell, a thin-film silicon solar cell that can significantly lower the manufacturing cost by using a thin film of silicon as the light absorption layer on a substrate such as glass is attracting attention. Thin-film silicon solar cells can be manufactured with a solar cell having a thickness of about 1/100 of the substrate-type silicon solar cell.

Amorphous silicon thin film solar cells are the first among thin film silicon solar cells that have been developed and are now being used for home use. Amorphous silicon solar cells can form amorphous silicon by chemical vapor deposition, which is suitable for mass production and inexpensive to manufacture, dangling bonds of silicon atoms present in large quantities in amorphous silicon. bond), the conversion efficiency is too low compared to the substrate-type silicon solar cell. In addition, the amorphous silicon solar cell has a problem in that a deterioration phenomenon of decreasing efficiency with use of a relatively short lifespan appears.

The crystalline silicon thin film solar cell was developed to supplement the disadvantage of the amorphous silicon thin film solar cell having the above problems. Since the crystalline silicon thin film solar cell uses crystalline silicon as the light absorbing layer, the characteristics of the solar cell are superior to those of the amorphous silicon thin film solar cell using amorphous silicon as the light absorbing layer.

However, there is a problem that the crystalline silicon thin film solar cell is not easy to modularize. The final finished product of the crystalline silicon thin film solar cell is composed of a plurality of unit cells in which an n-type silicon layer, an i-type silicon layer, and a p-type silicon layer are sequentially stacked on a glass substrate, and the n-type is formed through an electrode layer between unit cells. The (p-type) silicon layer and the p-type (n-type) silicon layer have a structure in which they are electrically connected in series with each other. In this case, in order to apply a voltage to the n-type silicon layer, the electrode layer formed under the n-type silicon layer should be made of a transparent conductive material such as ITO (Indium Tin Oxide). However, there is a problem in that the transparent conductive material generally deteriorates when the temperature is increased, so that it cannot be used in the crystalline silicon thin film solar cell. That is, in order to manufacture a crystalline silicon thin film solar cell, it is required to form amorphous silicon and then crystallize it at a temperature of 600 ° C. or higher. There was a problem.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, a crystalline silicon thin film type solar cell using a metal silicide layer instead of a transparent conductive layer as an electrode layer connected to the n-type silicon layer in series connection between a plurality of unit cells Its purpose is to provide a battery and a method of manufacturing the same.

In addition, an object of the present invention is to provide a crystalline silicon thin-film solar cell and a method of manufacturing the same by using a metal silicide layer instead of a transparent conductive layer as an electrode layer connected to the n-type silicon layer in the manufacturing process. .

In order to achieve the above object, a solar cell manufacturing method according to the present invention comprises the steps of (a) forming a first electrode layer on a substrate; (b) forming a first amorphous silicon layer on the first electrode layer; (c) forming a second amorphous silicon layer on the first amorphous silicon layer; (d) forming a third amorphous silicon layer on the second amorphous silicon layer; (e) crystallizing the first to third amorphous silicon layers to form first to third crystalline silicon layers; (f) etching the first to third crystalline silicon layers to form a plurality of unit cells; (g) etching the first to third crystalline silicon layers to form a first contact hole exposing the first electrode layer; (h) forming a mask layer; (i) etching the mask layer to form a second contact hole exposing the third crystalline silicon layer; And (j) forming a second electrode layer.

The first and second electrode layers may include any one or two or more metals of Ni, Al, Ti, Ag, Au, Co, Sb, Pd, Cu.

The method of forming the amorphous silicon layer may include a chemical vapor deposition method.

Crystallization of the amorphous silicon layer may include a solid phase crystallization method and a metal induced crystallization method.

 In the step (f), the etching method of the crystalline silicon layer may include a laser etching method.

In the step (e), a metal silicide layer may be formed in the boundary region between the first electrode layer and the first amorphous silicon layer.

The first crystalline silicon layer of any unit cell of the plurality of unit cells formed in the step (f) is connected to the third crystalline silicon layer of the adjacent cell through the step (j), and the first unit cell of the arbitrary unit cell is connected. The tricrystalline silicon layer and the first crystalline silicon layer of the adjacent cell may be connected.

The method may further include texturing the surface of the substrate.

The method may further include forming an anti-reflection layer on the substrate.

In order to achieve the above object, a solar cell according to the present invention is composed of a plurality of unit cells in which a first silicon layer, a second silicon layer and a third silicon layer are sequentially stacked on a substrate, the first cell The silicon layer is characterized in that it is electrically connected to the conductor pattern formed below.

The substrate may comprise glass and plastic.

The first silicon layer may be an n-type silicon layer and the third silicon layer may be a p-type silicon layer.

The first to third silicon layers may be crystalline silicon layers.

The conductor pattern may include metal or metal silicide.

The first silicon layer of any unit cell of the plurality of unit cells and the third silicon layer of the adjacent cell may be connected, and the third silicon layer of the arbitrary unit cell and the first silicon layer of the adjacent cell may be connected. have.

According to the present invention, by using a metal silicide layer instead of a transparent conductive layer as an electrode layer connected to the n-type silicon layer, there is an effect that various characteristics of the solar cell are not deteriorated in the manufacturing process of the crystalline silicon thin film type solar cell.

DETAILED DESCRIPTION The following detailed description of the invention refers to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein may be embodied in other embodiments without departing from the spirit and scope of the invention with respect to one embodiment. In addition, it is to be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled. Like reference numerals in the drawings refer to the same or similar functions throughout the several aspects.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

1A to 1K are views illustrating a configuration of a solar cell manufacturing method according to an embodiment of the present invention. For reference, in the above drawings, the bottom view is a cross-sectional view of each step, and the top view is a plan view showing only a part of the total area of the solar cell for convenience.

First, referring to FIG. 1A, an anti-reflection layer 110 is formed on a substrate 100 as a first step of a manufacturing process of a solar cell.

In the solar cell, the substrate 100 is preferably made of a transparent material for absorbing sunlight, and may include, for example, glass and transparent plastic. In this case, it is preferable that the surface of the substrate 100 is textured to form a roughness (not shown). This is to reduce the light reflected from the substrate surface of the solar cell and to scatter the light as it enters the solar cell, thereby increasing the effective absorption of light through the solar cell and increasing the output current, thereby increasing the output current. to be.

The anti-reflection layer 110 serves to prevent a phenomenon in which light incident through the substrate 100 is not absorbed by the silicon layer and is directly reflected to the outside, thereby reducing the efficiency of the solar cell. The antireflection layer 110 may include silicon oxide (SiOx) or silicon nitride (SiNx). The anti-reflection layer 110 may be formed of low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD), or the like.

Next, referring to FIG. 1B, the first metal layer 120 is formed in a pattern shape on the antireflection layer 110. As will be described below, the first metal layer 120 serves as an electrode layer connected to the n-type silicon layer 130, and for this purpose, the first metal layer 120 is formed at a position where the first contact hole 160 is formed.

The first metal layer 120 may include any one or two or more metals of Ni, Al, Ti, Ag, Au, Co, Sb, Pd, and Cu. The method of forming the first metal layer 120 may include physical vapor deposition (PVD), such as ink jet printing, screen printing, evaporation, or sputtering. ) Can be used. As the method of patterning the first electrode layer 120, a wet etching method, a dry etching method including laser scribing, or the like may be used.

1C to 1E, the n-type amorphous silicon layer 130, the i-type (intrinsic) amorphous silicon layer 140, and the p-type amorphous silicon layer 150 are formed on the first metal layer 120. Form sequentially.

The amorphous silicon layers 130, 140, and 150 may be formed by chemical vapor deposition such as LPCVD, PECVD, hot wire chemical vapor deposition (HWCVD), or the like. The thickness of each layer of the amorphous silicon layers 130, 140, and 150 may be a thickness generally adopted in a thin film silicon solar cell.

The n-type amorphous silicon layer 130 is preferably formed by in-situ doping the n-type dopant during the process of forming the amorphous silicon layer. It is preferable to use phosphorus (P) as an n-type dopant. The doping concentration can be applied to the doping concentration commonly employed in thin film silicon solar cells.

The p-type amorphous silicon layer 150 may also be formed by in-situ doping of the p-type dopant during the process of forming the amorphous silicon layer. It is preferable to use boron (B) as a p-type dopant. The doping concentration is the same as that of forming the n-type amorphous silicon layer 130 described above.

Next, referring to FIG. 1F, the n-type, i-type, and p-type amorphous silicon layers 130, 140, and 150 are crystallized and heat treated to form n-type, i-type, and p-type crystalline silicon layers 135, 145, and 155. Form. This completes the n-i-p structure for the thin film crystalline silicon solar cell in which the n-type crystalline silicon layer 135, the i-type crystalline silicon layer 145, and the p-type crystalline silicon layer 155 are sequentially stacked.

It is preferable to use solid phase crystallization (SPC) as the method for crystallizing the amorphous silicon layer. In this case, the crystallization temperature is preferably in the range of 600 ~ 700 ℃. In order to lower the crystallization temperature than using the SPC method, metal induced crystallization (MIC), which is a method of crystallizing amorphous silicon using a metal catalyst, may be used.

Meanwhile, activation of the n-type dopant and the p-type dopant, which are doped in the n-type amorphous silicon layer 130 and the p-type amorphous silicon layer 150, is also simultaneously performed in the crystallization heat treatment step of the amorphous silicon layer. To the n-type dopant diffusion in this process there is a first i-type crystalline silicon layer may actually be crystalline silicon layer n ^o. The use of the i-type (intrinsic) silicon layer as the light absorbing layer in the solar cell or the insulating layer which is superior to the n ^o (or p ^o ) silicon layer is better in terms of performance. Can be reduced. In order to prevent this, it may be more preferable to form a p ^o amorphous silicon layer doped with a lower concentration of the p-type dopant, rather than not doping at all, when the i-type amorphous silicon layer 140 is formed in the step of FIG. 1d. have.

In addition, in the crystallization heat treatment step of the amorphous silicon layer, the first metal layer 120 and the n-type amorphous silicon layer 130 react to change the phase of the first metal layer 120 into the metal silicide layer 122. Accordingly, in the present invention, the electrode layer which is finally in direct contact with the n-type crystalline silicon layer 135 is connected to the metal silicide layer 122.

Next, referring to FIG. 1G, n-type, i-type, and p-type crystalline silicon layers 135, 145, and 155 are etched to form a plurality of unit cells constituting a solar cell. In this step, the plurality of unit cells are electrically isolated from each other. As an etching method of the crystalline silicon layers 135, 145, and 155 for forming a plurality of unit cells, laser scribing, which is a kind of dry etching, may be used.

Next, referring to FIGS. 1H-1K, a process for electrically connecting a plurality of separated unit cells is performed.

Referring to FIG. 1H, the first contact hole 160 is formed by etching the n-type, i-type, and p-type crystalline silicon layers 135, 145, and 155. The first contact hole 160 exposes the n-type silicon layer to connect the n-type silicon layer between the plurality of unit cells and the p-type silicon layer of the adjacent cell. Of course, in the present invention, the metal silicide layer 122, which is connected to the n-type crystalline silicon layer 135 while being in contact with the first contact hole 160, is simultaneously exposed. As the etching method of the crystalline silicon layers 135, 145, and 155 for forming the first contact hole 160, a dry etching method including a wet etching method and a laser scribing method may be used. In this case, the metal silicide layer 122 may serve as an etching stop layer in the etching process of the n-type crystalline silicon layer 135.

Next, referring to FIG. 1I, the mask layer 170 is entirely formed in the state where the step of FIG. 1H is completed. The mask layer 170 may passivate portions other than the region where the second contact hole 180 is to be formed to form the second contact hole 180. The mask layer 170 may include silicon oxide (SiOx), silicon nitride (SiNx), or resin. As the method of forming the mask layer 110, an LPCVD method, a PECVD method, a spin on dielectric (SOD) coating method, or the like may be used.

Next, referring to FIG. 1J, the mask layer 170 is etched to form a second contact hole 180. The second contact hole 180 exposes the p-type silicon layer in order to connect the n-type silicon layer between the plurality of unit cells and the p-type silicon layer of the adjacent cell. As an etching method of the mask layer 170 for forming the second contact hole 180, a dry etching method including a wet etching method and a laser scribing method may be used.

Next, referring to FIG. 1K, the second electrode layer 190 is formed on the entire surface in the state where the step of FIG. 1J is completed, and then patterned. The material of the second electrode layer 190 is not particularly limited as long as it can be used as a general wiring material, but a metal is preferably used. The formation and patterning method of the second electrode layer 190 is the same as that of the first electrode layer 120 described above.

When the step 1k is completed, the thin film crystalline silicon solar cell 10 according to the exemplary embodiment of the present invention is completed, and FIG. 2 is a plan view showing the configuration of the solar cell 10.

As illustrated, the solar cell 10 includes an n-type crystalline silicon layer 135, an i-type crystalline silicon layer 145, and a p-type crystalline silicon layer 155 sequentially stacked on the substrate 100. The n-type crystalline silicon layer 135 of any unit cell of the plurality of unit cells and the p-type crystalline silicon layer 155 of the adjacent cell through the metal silicide layer 122 and the second electrode layer 190 as the first electrode layer. Are connected, and the p-type crystalline silicon layer 155 of any unit cell and the n-type crystalline silicon layer 135 of the adjacent cell are connected, so that the plurality of unit cells are all electrically connected to one solar cell 10. ) To work. In particular, the solar cell 10 in the present invention has the following advantages by taking the configuration that the voltage is applied to the n-type crystalline silicon layer 135 through the metal silicide layer 122.

(1) Since the transparent conductive layer does not need to be used as an electrode layer connected to the n-type silicon layer, the transparent conductive layer is degraded during the crystallization process of amorphous silicon in the production of crystalline silicon thin film solar cells, thereby deteriorating various characteristics of the solar cell. It can prevent.

(2) Since the resistance of the metal silicide layer is lower than that of pure metal, the contact resistance between the n-type silicon layer and the electrode layer is lowered, thereby reducing the power consumption of the solar cell.

(3) As the light absorbing layer, the electron-hole mobility characteristics are much better than those of the amorphous silicon layer and the crystalline silicon layer having a low defect density is used, so the overall characteristics of the solar cell are excellent. In addition, since the crystalline silicon layer does not have deterioration characteristics due to light irradiation, the reliability of the product is increased during the life time.

(4) Excellent electron-electron collection characteristics due to the drift mechanism because the i-type (intrinsic) silicon layer is used as the light absorbing layer, which has better insulation than the p ^o or n ^o silicon layer doped at a low concentration. The performance of the solar cell is improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken in conjunction with the present invention. Variations and changes are possible. Such modifications and variations are intended to fall within the scope of the invention and the appended claims.

1a to 1k is a view showing the configuration of a solar cell manufacturing method according to an embodiment of the present invention.

2 is a plan view showing the configuration of a solar cell manufactured according to the method of FIG.

<Explanation of symbols for the main parts of the drawings>

100: substrate

110: antireflection layer

120: first metal layer

122: metal silicide layer

130: n-type amorphous silicon layer

135: n-type crystalline silicon layer

140: i-type amorphous silicon layer

145: i-type crystalline silicon layer

150: p-type amorphous silicon layer

155: p-type crystalline silicon layer

160: first contact hole

170: mask layer

180: second contact hole

190: second metal layer

Claims (15)

(a) forming a first electrode layer on the substrate; (b) forming a first amorphous silicon layer on the first electrode layer; (c) forming a second amorphous silicon layer on the first amorphous silicon layer; (d) forming a third amorphous silicon layer on the second amorphous silicon layer; (e) crystallizing the first to third amorphous silicon layers to form first to third crystalline silicon layers; (f) etching the first to third crystalline silicon layers to form a plurality of unit cells; (g) etching the first to third crystalline silicon layers to form a first contact hole exposing the first electrode layer; (h) forming a mask layer; (i) etching the mask layer to form a second contact hole exposing the third crystalline silicon layer; And (j) forming a second electrode layer Solar cell manufacturing method comprising a. The method of claim 1, The first and second electrode layers are any one of Ni, Al, Ti, Ag, Au, Co, Sb, Pd, Cu or two or more metals manufacturing method of the solar cell, characterized in that. The method of claim 1, The method of forming the amorphous silicon layer is a solar cell manufacturing method comprising a chemical vapor deposition method. The method of claim 1, The method of crystallizing the amorphous silicon layer is a solar cell manufacturing method comprising a solid phase crystallization method and a metal induced crystallization method. The method of claim 1, The method of etching the crystalline silicon layer in the step (f) is characterized in that it comprises a laser etching method. The method of claim 2, The method of claim 1, wherein the first electrode layer comprises a metal or a metal silicide. The method of claim 1, The first crystalline silicon layer of any unit cell of the plurality of unit cells formed in the step (f) and the third crystalline silicon layer of the adjacent cell are connected through the step (j), and the first unit cell of the arbitrary unit cell is connected. 3 A method of fabricating a solar cell, wherein the crystalline silicon layer is connected to the first crystalline silicon layer of an adjacent cell thereof. The method of claim 1, The method of manufacturing a solar cell further comprising the step of texturing the surface of the substrate. The method of claim 1, Forming an anti-reflection layer on the substrate further comprises a solar cell manufacturing method. A plurality of unit cells, in which a conductor pattern, a first silicon layer, a second silicon layer, and a third silicon layer are sequentially stacked on the substrate and having a first contact hole exposing the conductor pattern; A mask layer formed on the unit cell and having a second contact hole exposing the third silicon layer; And An electrode layer formed on the mask layer and connecting the plurality of unit cells in series through the first contact hole and the second contact hole; Solar cell comprising a. The method of claim 10, The substrate is a solar cell, characterized in that it comprises glass and plastic. The method of claim 10, Wherein the first silicon layer is an n-type silicon layer and the third silicon layer is a p-type silicon layer. The method of claim 10, The first to third silicon layers are solar cells, characterized in that the crystalline silicon layer. The method of claim 10, The conductor pattern is a solar cell, characterized in that it comprises a metal or metal silicide. The method of claim 10, The first silicon layer of any unit cell of the plurality of unit cells and the third silicon layer of the adjacent cell are connected, and the third silicon layer of the arbitrary unit cell and the first silicon layer of the adjacent cell are connected. Solar cell, characterized in that.

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