KR20180061102A - Patterning method of electrode of solar cell and electrode of solar using the same - Google Patents

Abstract

The present invention relates to a method for forming an electrode of a solar cell. The present invention provides technology for increasing efficiency by increasing a light receiving area on a surface and reducing resistance by increasing a height while reducing the area of the electrode by including a high aspect ratio in a structure of 30 μm or less when forming the electrode of the silicon solar cell through an electrode pattern forming process of an imprinting method in a resin layer.

Description

[0001] The present invention relates to a method of forming an electrode of a solar cell,

The present invention relates to a method for forming an electrode of a solar cell.

The largest portion of the cost of solar cells is the price of silicon wafers used as substrates. Therefore, in order to reduce the cost of the solar cell, a thinner and less expensive substrate is used.

In recent years, studies have been made to manufacture a high-efficiency solar cell using a substrate having a thickness of 200 탆 or less which is thinner than the conventional thickness of about 300 to 400 탆.

In order to manufacture a high efficiency solar cell, a passivation layer made of an insulating film such as SiN x, SiO 2 or the like is formed on the front and rear surfaces of the solar cell, and a minority carrier generated by the incident sunlight Thereby preventing recombination.

Particularly, in order to obtain high efficiency in a thin substrate, the insulating property of the protective film should be excellent, and an insulating film having excellent reflectance should be formed on the rear surface of the solar cell.

Among the conventional methods of forming the electrode pattern, there is a method of forming a pattern by a photolithography process, followed by wet etching using a chemical etching solution. Although this method is generally used for manufacturing high-efficiency solar cells, it has a disadvantage that it is not suitable for a low-cost mass-production process because of its high process cost.

Si-rich SiN x films, which can obtain high efficiency when applied to insulating films of solar cells, can not perform wet etching because of excellent protective film characteristics and excellent optical characteristics. Therefore, when SiN x film is used as an insulating film, There is a problem that a metal electrode pattern can not be formed by the lithography process.

As a method for forming an electrode pattern for both the SiNx film and the SiO 2 insulating film, there are a plasma etching method, a laser ablation method (referred to as laser ablation) , Mechanical abrasion method, and the like are described as follows.

In the plasma etching method, an electrode pattern is formed on a SiNx film by using an SF6 plasma and a plasma mask. However, this method has a problem that the process cost is high, the efficiency is reduced due to the surface damage caused by the plasma, and it is difficult to apply to the mass production process.

In the laser ablation method, an electrode pattern is formed on a SiN x film by using a KrF excimer laser or an Nd: YAG laser. A plurality of holes are formed in the rear electrode. For example, 10000 holes are formed in an area of 100 cm 2. However, in this method, since the holes formed in the rear electrode are manufactured one by one, the process time is too long.

The mechanical polishing method is a technology that is being prepared for mass production. It has the advantage that the electrode formation speed is fast since the whole back electrode can be polished by a plurality of blades to make the hole into a single process. However, this method has a disadvantage in that it can only make a linear electrode pattern and can not form any other pattern form. In particular, since the height of the blade is constant from the wafer surface, if the wafer surface is not flat, There is a problem that is difficult to make.

A prior art that applies a mechanical polishing method to the manufacture of solar cells is US Pat. No. 4502225. Here, the surface of the solar cell is textured using a mechanical scriber, and a solar cell having a recessed electrode structure is manufactured. However, since the electrode in such a depressed electrode structure is formed after deeply dugging into the substrate to a depth of about 70 to 80 탆, it is different from forming the electrode pattern by removing only the insulating film, and it is impossible to remove only the insulating film.

In order to fabricate a high efficiency solar cell, the optimum size of the back electrode is 1 to 2%, the electrode width is within 30 μm, and the electrode interval is within 3 mm. I can not.

That is, in the conventional method of forming an electrode of a conventional silicon solar cell, it is difficult to form an electrode within 30 μm, and an aspect ratio of the electrode is also poor.

Korean Patent Publication No. 10-2003-0015590 Korean Patent Publication No. 10-2003-0015741

SUMMARY OF THE INVENTION The present invention has been conceived to solve the above-described problems, and it is an object of the present invention to provide a silicon solar cell having a high aspect ratio in a structure of 30 탆 or less, The present invention provides a method of forming an electrode of a solar cell that can increase the efficiency and increase the light receiving area on the surface.

As a means for solving the above-mentioned problems, the present invention provides a method for manufacturing a semiconductor device, comprising: a first step of forming a resin layer on a surface of a substrate; A second step of patterning the resin layer by pressing the electrode forming mold on the resin layer; Forming an electrode material layer on the patterned resin layer; And removing the resin layer to form an electrode. The present invention also provides a method of forming an electrode of a solar cell.

Further, in the second step, it is possible to provide a method of forming an electrode of a solar cell, which is a step of pressing an electrode forming mold having a concavo-convex pattern corresponding to an electrode pattern on a mold to remove a resin material at an electrode forming site.

In the third and fourth steps, the electrode material layer is formed at a height equal to or higher than the height of the patterned resin. In the fourth step, the electrode material layer is removed while leaving the electrode material filled in the concave pattern on the resin And then removing the residual resin layer constituting the concave pattern.

In the method of forming an electrode of a solar cell according to the present invention, the electrode material layer may be formed of a material selected from the group consisting of Au, Pt, Pd, Ru, Ni, Cu, Sn, In, Zn, Fe, Ti, Ag and Mn, or a combination of two or more thereof.

In particular, the electrode material layer may be formed by any one of electroplating, electroless plating and electroconductive paste printing.

The present invention relates to a silicon solar cell having a high aspect ratio in a structure of 30 탆 or less and increasing the height of the electrode while reducing the area of the electrode, There is an effect that the improvement can be increased.

FIG. 1 is a flow chart of a method of forming an electrode of a solar cell according to the present invention.
2 is a process conceptual diagram showing the process sequence of FIG.

Hereinafter, the configuration and operation according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description with reference to the accompanying drawings, the same reference numerals denote the same elements regardless of the reference numerals, and redundant description thereof will be omitted. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

FIG. 1 is a flow chart of a method of forming an electrode of a solar cell according to the present invention. 2 is a process conceptual diagram showing the process sequence of FIG.

1 and 2, a method of forming a solar cell according to the present invention includes a first step of forming a resin on a surface of a substrate, a second step of patterning the resin by pressing the electrode forming mold on the resin, Forming a layer of electrode material on the patterned resin, and forming the electrode by removing the resin.

In the first step, a process of applying the resin 120 to the surface of the substrate 110 is performed. In this case, the substrate 110 is preferably a silicon semiconductor substrate. The silicon semiconductor substrate 110 is made of a single crystal or polycrystalline silicon. The silicon semiconductor substrate 110 contains a conductive semiconductor impurity such as boron and has a resistivity of, for example, about 1.0 to 2.0? Cm. In the case of a single crystal silicon substrate, it is formed by a pulling method or the like, and in the case of a polycrystalline silicon substrate, it is formed by a casting method or the like. The ingot of silicon formed by an impression method, casting, or the like is sliced into a thickness of 200 mu m or less, preferably 150 mu m or less, and is referred to as a silicon substrate 110. [ In the following description, a p-type silicon substrate is used, but an n-type silicon substrate may also be used. In order to clean the sliced surface of the silicon substrate 110, the surface of the silicon substrate 110 is slightly etched with NaOH, KOH, or hydrofluoric acid or fluoro-nitric acid, and then the surface of the silicon substrate 110 (light receiving surface) , An uneven surface (roughened surface) having a light reflectance reducing function can be formed by dry etching or wet etching, and then a step of forming a resin layer can be performed.

The resin layer 120 may be formed of epoxy resin, photosensitive resin, polyimide photosensitive resin, UV curable resin (urethane acrylate, epoxy acrylate, silicone acrylate, polyester acrylate, epoxy, vinyl ether) Any one of the curing resins may be used. When the resin layer is formed of a liquid material such as the photosensitive resin liquid, the resin layer may be formed by a conventional spin coating method or a slit coating method. Various materials such as a photoresist, a dry film resist, and an ultraviolet curable resin may be used It is needless to say that any material having a photosensitive property may be used. For example, it can be formed by coating a resin layer of an epoxy type, a polyimide type, or a Novolak type.

In the second step, the electrode forming frame 130 is pressed on the resin layer 120 to process the resin layer. In particular, the electrode forming frame 130 may be a mold having a concavo-convex pattern corresponding to an electrode pattern to be formed in accordance with the second step process of the imprinting method. In this case, the electrode forming mold may be a glass mold or a metal mold, and the metal mold may be a mold made of Ni, Cr, Au or the like.

Particularly, in the present step, the depth of the concavo-convex pattern formed in the electrode forming frame 130 is preferably less than the thickness of the resin layer so that the resin at the electrode formation site can be removed due to the pressing of the concavo-convex pattern. In this case, the resin finely remaining on the substrate surface of the pressed portion can be removed by a method such as etching or ashing.

Thereafter, a process of forming an electrode material layer 140 on the patterned resin may be performed in a three-step process. The electrode material layer may be formed in such a manner that the electrode material is filled in the patterned concave pattern portion of the resin layer 120 or may be formed in a structure covering the entire resin layer at a height equal to or greater than the height of the resin layer as shown .

The electrode material layer 140 may be formed by a variety of methods. For example, electroplating, electroless plating, and printing of a conductive paste may be applied. At this time, the electrode may be formed while the solar cell is gradually lowered while the electroplating or the electroless plating is proceeded to immerse the solar cell in the plating solution. In this case, the electroplating or electroless plating process is performed before the solar cell is immersed in the plating solution of the plating bath, and the motor is operated while the plating process is in progress to lower the solar cell at a constant rate by immersing the wire into the plating solution I will. As the plating metal, Cu, Ag, Ni, Cr, Co, or Ti can be used.

In this case, the electrode material layer 140 may be formed of one or two selected from the group consisting of Au, Pt, Pd, Ru, Ni, Cu, Sn, In, Zn, Fe, Cr, Co, Or a mixed composition or alloy composition of at least two kinds can be formed by a plating method.

In the case of the conductive paste printing method, a mixture in which conductive particles are mixed with a metal material, an organic solvent or the like can be applied. As an example of such a paste, it is of course possible to use all known conductive pastes, for example, a paste containing a dopant-coated silver powder, an inorganic binder, a metal oxide, a binder and an organic solvent. In this case, the dopant may be at least one selected from the group consisting of silver metaphosphate, silver orthophosphate, silver pyrophosphate, silver phosphide, silver hexafluorophosphate, silver antimonic acid, hexafluoroantimonic acid, Chromium oxide, silver cyanide, silver iodide, silver iodide, molybdic acid silver, potassium silver cyanide, rubidium silver iodide, bromic acid silver, bromine silver, silver selenide silver silver telluride and selenized silver , And the like can be applied.

In the fourth step, the resin may be removed to form an electrode. That is, as in step S 4, the electrode material may be removed in the same manner as the height of the resin layer, and then the resin may be further removed in step S 5.

In the silicon solar cell, it is difficult to form an electrode having a thickness of 30 .mu.m or less and a poor aspect ratio even if it can be formed. However, if the imprint technique is used to remove uneven patterns on the resin coated on the substrate with the unevenness of the mold, it is possible to obtain an electrode having a thinner and better aspect ratio than the conventional electrode forming method, It is advantageous in that the processing cost is small and the manufacturing time is short.

If imprint technology is used to reduce the area of the electrodes in the solar cell and increase the height, it is possible to expect the efficiency to be constantly increased because of the low resistance and the area receiving the light on the surface. Therefore, the imprint technology is advantageous in mass production application and is cheaper than existing electrode forming technology.

In the foregoing detailed description of the present invention, specific examples have been described. However, various modifications are possible within the scope of the present invention. The technical idea of the present invention should not be limited to the embodiments of the present invention but should be determined by the equivalents of the claims and the claims.

110: substrate
120: Resin layer
130: electrode forming frame
140: electrode material layer

Claims (1)

A first step of forming a resin layer on a substrate surface;
A second step of patterning the resin layer by pressing the electrode forming mold on the resin layer;
Forming an electrode material layer on the patterned resin layer; And
And removing the resin layer to form an electrode,
In the second step, the electrode forming frame having the concavo-convex pattern corresponding to the electrode pattern is pressed on the mold to remove the resin material at the electrode forming portion,
In the step 3, the electrode pattern is formed of a mixed composition of one or more selected from the group consisting of Au, Pt, Pd, Ru, Ni, Cu, Sn, In, Zn, Fe, Cr, Co, Ti, Forming an electrode material layer above the height of the resin patterned with the alloy composition,
The method of claim 4, wherein after removing the electrode material layer leaving the electrode material filled in the concave pattern on the resin, the remaining resin layer constituting the concave pattern is removed.

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