KR101187749B1 - Method for forming elctrode of solar cell device - Google Patents

Abstract

 In the method of forming a metal electrode wiring in a solar cell device using a selective deposition method, forming an interlayer phosphorus diffusion treatment, removing the phosphorus silicate glass layer, and forming an arc layer And removing only the arc layer by applying the selective deposition process including removing the arc layer on the electrode part for forming the electrode and adhering acess treatment, selective nickel deposition, selective copper deposition, and selective cap deposition. It is possible to form the metal electrode wiring of the solar cell, which requires the selective deposition step of forming the electrode only on the uneven part, followed by annealing, and then an edge isolation process.

Description

Electrode Formation Method of Solar Cell {METHOD FOR FORMING ELCTRODE OF SOLAR CELL DEVICE}

The present invention relates to a method for forming electrode wirings of a solar cell, and in particular, to a method of forming an electrode of a solar cell, which realizes a high efficiency and ultra low cost that can be completely embedded in a metal layer without a separate firing process using a selective deposition process technology. It is about.

The metal electrode of the silicon solar cell is now mainly screen-printed using silver paste. The screen printing technique widely used in the commercially available solar cells has the advantages of relatively low cost of materials and unit processing equipment, a large amount of products can be produced in a large amount of time in the air in a short time, and an appropriate electrode material can be selectively applied. have. However, this silver paste screen printing process has a disadvantage in that three equipments are applied and a long process time is required, such as a subsequent firing process. Silver paste applied screen printing technique, which is mainly used for screen printing, is very sensitive to process variables such as temperature, gas, and pressure during heat treatment process due to the nature of materials. (Finger bar) there is a problem that can not minimize the design (Design). In addition, the electrode material itself contains a glass frit component, which is a barrier to improvement in efficiency due to a very high specific resistance. In addition, the Ag front electrode formed by screen printing on the front of the emitter has a very high electrode resistance due to the phenomenon of diffusion penetration into the substrate starting from the bonding surface of the front electrode and the emitter surface during the heat treatment process. It can be large and this leads to a decrease in electrode efficiency. In addition, as the thickness of the silicon solar cell becomes thinner, defects in breaking the substrate due to pressure during silver screen printing are also increasing. Therefore, it is necessary to develop a new electrode formation method to overcome this problem. During printing and high temperature firing, there is a risk that defects will increase as the silicon wafer becomes thinner, and the resistance caused by the glass frit in the Ag electrode becomes a barrier to high efficiency. As the raw material price of silver is rising rapidly, new materials, processes, and equipment technologies are needed to replace silver (Ag) to reduce production costs.

The present invention has been made under the above-described background, and an object of the present invention is to form a nickel / copper electrode using a selective electrode plating process to realize low cost and high efficiency, thereby improving the efficiency and cost of the entire silicon solar cell. The present invention provides a method for forming an electrode of a solar cell.
Another object of the present invention is to provide a method of forming an electrode of a solar cell, which implements a silicon solar cell having low cost and high efficiency by replacing a screen printing method using silver paste in the field of a silicon solar cell.

An electrode forming method of a solar cell according to an embodiment of the present invention for achieving the above object, as a method of forming an electrode on the solar cell using a selective deposition method,
Forming a phosphorus diffusion layer to form a P type or N type semiconductor on a silicon substrate, removing the phosphorus silicate glass layer, which is an oxide film produced in the formation of the phosphorus diffusion layer, for light capture on the phosphorus diffusion layer Forming texturing to adjust the roughness of the surface of the cell and forming an arc layer on the phosphor diffusion layer; And
In order to form the electrode, the arc layer of the site where the electrode is to be formed is removed to perform a patterning process.Then, the arc layer is cleaned, the arc layer is washed, and after the Adhersion Access treatment, the nickel- A pretreatment layer is formed to form a copper (Ni / Cu) electrode, a selective nickel deposition layer is formed on the pretreatment layer, and an annealing step of an annealing step is performed to form a selective copper deposition layer. It provides a method for forming an electrode of a solar cell comprising the step of forming a selective cap layer layer on the selective copper deposition layer.

According to the solar cell electrode forming method of the present invention, a metal plating layer can be formed by performing an electroless plating method without undergoing a separate firing process. When the copper (Ni-Cu) process is replaced, the electrode formation efficiency can be improved due to the reduction of the resistance and the reduction of the electrode area.
Further, according to the electrode forming method of the solar cell of the present invention, after patterning the metal electrode forming portion of the arc layer, by using the electroless plating method to control the formation of the nickel or copper layer on the arc layer, only the metal electrode forming portion is selectively selected. The deposition eliminates the need for a separate photoresist forming process, and by selectively depositing copper having low resistance, the electrode formation efficiency of the solar cell can be improved by reducing the electrode area of the solar cell.

1A to 1L are cross-sectional views illustrating respective processes of the method for forming metal wirings of a semiconductor device according to the present invention, respectively.
2A and 2B are diagrams showing actual experimental results of the processes performed in FIG. 1.
2 c and 2 d show the results of surface component analysis through AES (Auger Electron Spectrascopy) analysis in order to confirm such selective characteristics.

Hereinafter, a method of forming an electrode of a solar cell according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The same or similar reference numerals will be given to the same or similar parts throughout the drawings.
1A to 1L are cross-sectional views illustrating respective processes of the method for forming metal wirings of a semiconductor device according to the present invention, respectively.
1A and 1B, a phosphorous or boron diffusion layer 110 is formed as shown in FIG. 1B to form a P-type or N-type semiconductor on the silicon substrate 100 of FIG. 1A. The forming of the phosphorus diffusion layer (P-doped) 110 may include a method of performing phosphorusyl chloride (POCl ₃ ) treatment and a method of performing phosphorus diffusion (P doping).
Subsequently, wet etching or dry etching is performed to remove the phosphorus silicate glass (PSG) layer 120 shown in FIG. 1C, which is an oxide film formed in the formation of the phosphor diffusion layer 110. In this case, the cell silicate glass (PSG) layer 120 may be completely removed, or a method of leaving the phosphorus silicate glass (PSG) layer 120 of about 10 to 100A (angstrom) may be used.
As shown in FIG. 1D, a dry etching process including wet etching or plasma etching to adjust the roughness of the surface of the cell for light capture on the phosphor diffusion layer 110. The texturing process 130 is performed.
Referring to FIG. 1E, the efficiency of light capture is maximized through silicon nitride (SiN _x ) deposition to form an arc layer (ARC: Anti Reflective Coating) 140 on the phosphor diffusion layer 110. As a method of forming an arc, physical vapor deposition or chemical vapor deposition can be used. Arclayer is not limited to the silicon nitride, and may include, for example, nitride (SiN _x : x = 0.1 ~ 80), silicon oxynitride (SiON), or silicon oxide (SiO _x ) film, but this is only an example. It is not limited to this, Any one which exhibits an equivalent or similar function may be sufficient.
Subsequently, FIG. 1F illustrates a patterning process through dry etching and laser scribing including wet etching or plasma etching to lower contact resistance with a silicon substrate as a preliminary step for forming a front electrode on the deposited arc layer 140. Perform 150. The method of removing the arc layer on the electrode for forming the electrode is a wet etching method using a mask, a wet drop printing method, a wet etching method by applying a slit mold suitable for the electrode gap, Alternatively, the laser scribing method may be used, but the present invention is not limited thereto, and any one may perform the same or similar functions.
Subsequently, a cleaning process 160 for removing and modifying the surface foreign matter is performed as shown in FIG. 1G. After the electrode patterning process 150, an Advice Access process is immediately performed.
FIG. 1h is a step of forming a pretreatment layer 170 by a pretreatment process to form a nickel-copper (Ni / Cu) electrode, thereby increasing adhesion of a nickel (Ni) deposition layer 180 which is a next process. Giving is a step. Such Adherence Access treatment proceeds with a cleaning treatment after a hydrofluoric acid (DHF: Diluted HF) treatment step if there is a process delay after patterning. The hydrofluoric acid (DHF) treatment component consists of hydrofluoric acid + ultrapure water (HF + DIwater: Deionized water), the concentration of hydrofluoric acid (HF) is in the range of 0.05% to 20%, and the treatment time is 1 second to 3 minutes. Post-cleaning is DI water rinsing and the treatment time is from 1 second to 1 minute. In the Advice Access Treatment, the applied solution contains palladium chloride (PdCl ₂ ), DI, hydrochloric acid (HCl), sulfuric acid (H ₂ SO ₄₎ , and the composition is 0.01-3 g / L of palladium chloride (PdCl ₂ ). Range, hydrochloric acid (HCl) in the range of 1-20 ml / L, sulfuric acid (H ₂ SO ₄ ) in the range of 1-20 ml / L. The advanced access treatment temperature ranges from -30 ^o C to 80 ^o C with a treatment time of 1 second to 10 minutes.
The above-described processing temperature range, components, and the like are not limited to those described above as an embodiment, and those skilled in the art will be able to implement them differently without departing from the spirit and scope of the present invention.
FIG. 1I illustrates a process of forming a selective nickel (Ni) deposition layer 180 on the pretreatment layer 170, wherein the deposition solution is nickel (Ni) 0.01-10 g / L, phosphoric acid (H ₂ PO ₂ ) 0.5- 8%, aqueous ammonia (NH ₄ OH) 0.1-5%, ammonium chloride (NH ₄ Cl) 0.1-5% solution, the treatment temperature of selective nickel (Ni) deposition is -30 ^o C to 80 ^o C, The treatment time is from 1 second to 10 minutes. The thickness of the selective nickel layer is deposited in the range of 50 kPa to 3um in order to increase the stability of the diffusion barrier layer to minimize the decrease in resistance and copper diffusion. Subsequent cleaning processes should proceed immediately after the formation of the selective nickel deposition layer 180. In the selective deposition process, in addition to the selective nickel deposition, deposition of cobalt (Co), tungsten (W) and the like is also possible. After the selective nickel deposition, the cleaning process may be performed, followed by heat treatment.
1J illustrates a heat treatment step. The annealing step 190 is a heat treatment for 1 minute-3 hours at room temperature-600 ^° C. At this time, the hydrogen reducing atmosphere may apply only hydrogen (H ₂ ), hydrogen (H ₂ ) + argon (Ar: 1-95%), hydrogen (H ₂ ) + nitrogen (N ₂ : 1-95%), and the like. The same hydrogen mixed gas may also be used. Heat treatment in an argon atmosphere or heat treatment in a nitrogen atmosphere may be used. The heat treatment process is to be carried out in a continuous process, it is carried out within 1 second ~ 5 minutes after the nickel deposition cleaning process.
1K shows a process for forming a selective copper deposition layer 200 after selective nickel deposition. In the selective copper deposition method, the deposition solution is composed of 0.5 to 10 g / L of copper, 1 to 20 g / L of sodium hydroxide (NaOH), 0.1 to 3% of methanol (HCHO), and 0.1 to 2% of ethylenediaminetetraacetic acid (EDTA). . The treatment of selective copper deposition is carried out for a period of 1 second to 60 minutes at a temperature of -10 ^o C to 90 ^o C. The deposition thickness of the selective copper deposition layer 200 is deposited in the range of about 500Å ~ 10um, and the selective copper deposition is deposited in the range of 20 seconds to 10 minutes after DI washing with water in the range of 20 seconds to 10 minutes. Repeat this 1-6 times.
In addition, the subsequent cleaning process should proceed immediately after the selective copper deposition. After the selective copper deposition and cleaning treatment, the heat treatment proceeds at room temperature-600 ^o C for 1 minute-3 hours. At this time, the hydrogen reducing atmosphere may be hydrogen only, or hydrogen mixed gas such as hydrogen + argon (1-95%), hydrogen + nitrogen (1-95%), and the like.The heat treatment may be performed in an argon atmosphere or in a nitrogen atmosphere. You can also do it. The heat treatment process is to be carried out in a continuous process, and after nickel deposition to be carried out within 1 second ~ 5 minutes after the cleaning process.
FIG. 1L finally shows a process for forming an optional caplayer layer 210 over the optional copper deposition layer 200. In the selective cap layer layer 210 deposition, silver (Ag), tin (Sn), silver (Ag) -tin (Sn), lead (Pb), nickel (Ni), or the like may be used as the deposition cap material.
2A and 2B are diagrams showing actual experimental results of the processes performed in FIG. 1.
FIG. 2A illustrates that nickel is selectively deposited only on an electrode forming portion on a silicon wafer. As shown in the drawing, nickel is not deposited on an arc layer, but a bus bar and a finger bar, which are electrode parts of a solar cell, are illustrated in FIG. It can be seen that only nickel is selectively deposited in bar).
FIG. 2 b shows a photograph of the deposition of copper, which has undergone selective deposition.
As shown in the figure, copper is not selectively deposited on the arc layer, and copper is selectively deposited only on the busbars and fingerbars, which are electrode portions of the solar cell, and shows results of selective nickel deposition and selective copper deposition.
2C and 2D illustrate the results of surface component analysis through AES (Auger Electron Spectrascopy) analysis to confirm the selective deposition characteristics of FIGS. 2A and 2B.
The upper photographic portion of FIG. 2C shows an image of a nickel / copper electrode, in which point # 1 is an electrode portion and Point # 2 is an arc portion where no electrode is formed.
As shown in the drawing, the electrode is formed only on the finger bar portion, and the black portion shows that the selective formation of the electrode is a silicon nitride portion, and the observed AES surface analysis results to check the component properties, The main component of Point # 1 (electrode part) is copper (Cu) and the main component of Point # 2 (non-electrode part) is silicon nitride shown in blue. In other words, in addition to the carbon (C), nitrogen (N) and oxygen (O) components on the wafer surface, nickel (Ni) and copper (Cu) components are found in the electrode portion, and electrode material-related components are hardly detected in the non-electrode portion. It can be seen that selective nickel and selective copper deposition are implemented.
According to the solar cell electrode forming method of the present invention as described above, it is possible to form a metal plating layer by performing an electroless plating method without going through a separate firing process, and in the electrode forming technology, alternative silver screen printing process of raw materials Selective Electrode Formation Nickel-Cu (Ni-Cu) process can be replaced by the reduction of the resistance and the electrode area due to the reduction of the electrode formation efficiency can be improved, and above all it is possible to reduce the electrode formation production cost more than 50%.
Further, according to the electrode forming method of the solar cell of the present invention, after patterning the metal electrode forming portion of the arc layer, by using the electroless plating method to control the formation of the nickel or copper layer on the arc layer, only the metal electrode forming portion is selectively selected. The deposition eliminates the need for a separate photoresist forming process, and by selectively depositing copper having low resistance, the electrode formation efficiency of the solar cell can be improved by reducing the electrode area of the solar cell.
So far, a method of forming an electrode of a solar cell according to an embodiment of the present invention has been described with reference to the drawings, but the above description is for illustrative purposes, and it should be understood that the present invention is not limited thereto. Is defined by the appended claims rather than the foregoing detailed description, which is intended to cover all such modifications and variations as are derived from their meaning and scope and their equivalent concepts. Should be interpreted as

100: silicon substrate 110: phosphor diffusion layer
120: phosphorus silicate glass (PSG) layer 130: texturing process
140: arc layer 150: electrode patterning process
160: washing step 170: pretreatment layer
180: selective nickel deposition layer 190: annealing step
200: selective copper deposition layer 210: caplayer layer

Claims (24)

A method of forming an electrode in a solar cell using a selective deposition method,
Forming a phosphorus diffusion layer to form a P type or N type semiconductor on a silicon substrate, removing the phosphorus silicate glass layer, which is an oxide film produced in the formation of the phosphorus diffusion layer, for light capture on the phosphorus diffusion layer Forming texturing to adjust the roughness of the surface of the cell and forming an arc layer on the phosphor diffusion layer; And
In order to form the electrode, the arc layer of the site where the electrode is to be formed is removed to perform a patterning process.Then, the arc layer is cleaned, the arc layer is washed, and after the Adhersion Access treatment, the nickel- A pretreatment layer is formed to form a copper (Ni / Cu) electrode, a selective nickel deposition layer is formed on the pretreatment layer, and an annealing step of an annealing step is performed to form a selective copper deposition layer. Forming a selective cap layer layer over the selective copper deposition layer.
The method of claim 1,
Forming the phosphor diffusion layer is a method of forming an electrode of a solar cell, characterized in that for performing a method of performing phosphoryl chloride treatment or phosphorus injection.
The method of claim 1,
Removing the phosphorus silicate glass layer is a method of forming an electrode of a solar cell, characterized in that by applying a wet etching method to remove the phosphorus silicate glass layer, or about 10 ~ 100 ~ thickness.
The method of claim 1,
In forming the arc layer, an arc layer forming method may be a physical vapor deposition method or a chemical vapor deposition method, and the arc layer may include silicon nitride (SiNx: x = 0.1 to 80), silicon oxynitride (SiON), and silicon nitride. (Si ₃ N ₄ ), or a silicon oxide (SiOx) film comprising a solar cell electrode forming method.
The method of claim 1,
The method of forming a solar cell electrode, characterized in that the wet etching by applying a mask in a method for removing the arc layer of the portion for forming the electrode.
The method of claim 1,
The method of forming a solar cell electrode, characterized in that the wet drop (Wet Drop) printing method is applied as a method for removing the arc of the site for the formation of the electrode.
The method of claim 1,
The method of forming a solar cell electrode, characterized in that the wet etching by applying a slit mold (Slit Mold) suitable for the electrode spacing as a method for removing the arc of the portion for forming the electrode.
The method of claim 1,
The method of forming an electrode of a solar cell, characterized in that the laser scribing (Laser Scribing) by a method of removing the arc of the portion for forming the electrode.
The method of claim 1,
After the patterning process, if there is a delay in the Adhesion Acess treatment process, a method of forming an electrode of a solar cell, characterized in that to perform a cleaning treatment after hydrofluoric acid (DHF: Diluted HF) treatment.
The method of claim 9,
The DHF treatment condition is composed of HF + DI, the concentration of HF ranges from 0.05% to 20%, the treatment time is 1 second to 3 minutes and the washing after this process is DI water washing and the processing time of 1 second to 1 minute Electrode formation method of a solar cell, characterized in that carried out as.
The method of claim 1,
In the Adherence Access treatment, selective nickel deposition, selective copper deposition, and selective cap deposition, the solution to which Adherence Access dp is applied is palladium chloride (PdCl ₂ ), ultrapure water (DI water), hydrochloric acid (HCl). , And sulfuric acid (H ₂ SO ₄ ) components, the composition of which is PdCl ₂ 0.01 ~ 3g / L, HCl is in the range of 1 ~ 20ml / L, H ₂ SO ₄ has a range of 1 ~ 20ml / L Electrode formation method of a solar cell, characterized in that.
12. The method of claim 11,
In an optional deposition step including the Adsorption Acess treatment, selective nickel (Ni) deposition, selective copper (Cu) deposition, and selective cap deposition, the advice access treatment temperature is 80 to -30 ^o C. ^o The temperature range of C, the treatment time has a temperature range of 1 second to 10 minutes, the electrode forming method of a solar cell.
12. The method of claim 11,
The cleaning after the access access treatment (Cleaning) is DI washing with water, and the electrode forming method of the solar cell, characterized in that having a processing time of 1 second ~ 1 minutes.
The method of claim 1,
In the selective deposition step including the adjuvant access treatment, selective nickel deposition, selective copper deposition, and selective cap deposition, the selective nickel deposition solution is nickel sulfate (NiSO ₄ ), phosphoric acid (H ₂ PO ₂ ), sodium hydroxide (NH ₄ OH), ammonium chloride (NH ₄ Cl), H ₂ O components, the composition is nickel (Ni) in the range of 0.01 to 10g / L, H ₂ PO ₂ 0.5 to 8%, NH ₄ OH 0.1 Method of forming an electrode of a solar cell, characterized in that having a range of ~ 5%, NH ₄ Cl 0.1 ~ 5%. The method of claim 14,
The treatment temperature of the selective nickel (Ni) deposition has a temperature range of -30 ^o C to 80 ^o C and the treatment time has a temperature range of 1 second to 10 minutes, the deposition time is a temperature range of 1 second to 10 minutes The thickness of the selective nickel layer has a deposition thickness in the range of 50 ~ 3um in order to increase the stability of the diffusion barrier layer to reduce the minimum resistance and copper diffusion, electrode formation method of a solar cell.
The method of claim 14,
Method for forming an electrode of a solar cell, characterized in that to perform a cleaning process immediately after the selective nickel deposition.
The method of claim 1,
Forming an electrode of a solar cell comprising the deposition of selective cobalt (Co) or tungsten (W) in the selective deposition step including the adjuvant access treatment, selective nickel deposition, selective copper deposition, selective cap deposition step Way.
The method of claim 1,
The heat treatment step is carried out for 1 minute-3 hours heat treatment at a temperature of -600 ^° C. At this time, the hydrogen reduction atmosphere is hydrogen + argon (1-95%), hydrogen + nitrogen (1- 95%), the case of using a hydrogen mixture gas, the heat treatment in an argon atmosphere, any one of heat treatment in a nitrogen atmosphere, the heat treatment process is to proceed to a continuous process, and after the nickel deposition cleaning treatment Method of forming an electrode of a solar cell, characterized in that the progress in 1 second to 5 minutes after the progress.
The method of claim 1,
In the selective deposition step including the adjuvant access treatment, selective nickel deposition, selective copper deposition, and selective cap deposition, the deposition solution of the selective copper deposition is capasulfate (CuSO ₄ ), sodium hydroxide (NaOH), methanol (HCHO). ), EDTA (ethylenediaminetetraacetic acid), H ₂ O components, the composition is copper 0.5 ~ 10g / L, sodium hydroxide 1 ~ 20g / L, methanol 0.1 ~ 3%, EDTA (ethylenediaminetetraacetic acid) ) Is a method for forming an electrode of a solar cell, characterized in that it comprises a 0.1 to 2% range.
20. The method of claim 19,
Treatment temperature of the selective copper deposition has a temperature range of -10 ^o C to 90 ^o C, a treatment time of 1 second to 60 minutes, a deposition time of 1 second to 10 minutes, the deposition thickness of the selective copper layer is 500 kW In the range of ~ 10um, the selective copper deposition is a 20 seconds to 10 minutes after the DI water washing process after the deposition process again 20 seconds ~ 10 minutes, the electrode of the solar cell, characterized in that repeated 1 to 6 times Forming method.
20. The method of claim 19,
After the selective copper deposition, a method of forming an electrode of a solar cell, characterized in that to perform a cleaning process immediately.

The method of claim 1,
In the selective deposition step including the adjuvant access treatment, selective nickel deposition, selective copper deposition, and selective cap deposition, silver (Ag), tin (Sn), silver (Ag) -tin as the deposition cap material of the selective cap deposition chamber. (Sn), lead (Pb), or nickel (Ni) comprising a method for forming an electrode of a solar cell.

delete delete

Images