CN111564521A - Preparation method of all-matte IBC solar cell - Google Patents

Abstract

This patent provides a method for preparing a full textured IBC solar cell, including a cleaning and texturing process, a selective emitter process, a mask layer deposition process, a surface field preparation process, an antireflection layer preparation process and an electrode fabrication process. The present invention increases the light absorption rate of the front surface by moving the electrodes to the back surface, thereby increasing the short circuit current. At the same time, both sides of the obtained battery are all suede surfaces, which greatly reduces the light reflectivity, further improves the light capture amount, greatly simplifies the process flow and reduces the cost.

Description

A kind of preparation method of full suede IBC solar cell

technical field

The invention belongs to the field of solar cells, in particular to a full-suede solar cell.

Background technique

Based on the purpose of reducing LCOE and improving cell efficiency, IBC (Interdigitated backcontact) cells are favored by photovoltaic researchers due to their excellent optical absorption and low internal resistance. Compared with N-PERT and PERC high-efficiency cells, the electrodes of IBC cells are located on the back, which not only facilitates the packaging of components, but also provides a large space for optimizing the series resistance. At present, the photolithography mask method is used in the production of the P+ doped region and the N+ doped region in the production of IBC cells, and the production cost is greatly increased due to the numerous process flows. Compared with the prior art IBC battery process, the preparation method of the present invention has the advantages of low production cost and fewer process steps.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to develop a method for preparing a full-textured IBC solar cell. It proposes to use silicon nitride as a mask layer, and then open a window through a laser ablation method to achieve doping in another area, which greatly simplifies the process flow and Reduced costs.

A method for preparing a full-textured IBC solar cell, characterized in that it comprises a cleaning and texturing process, a selective emitter process, a mask layer deposition process, a surface field preparation process, an antireflection layer preparation process and an electrode fabrication process;

The cleaning and texturing process includes:

1) Place the N-type silicon wafer in NaOH and H2O2 solution to clean the mechanical damage layer and surface oil on the surface of the silicon wafer;

2) The surface texture treatment of silicon wafers is carried out in the mixed solution of NaOH and single crystal texturing additive;

3) Neutralize the NaOH solution on the surface of the silicon wafer, clean the metal ions and the oxide layer in the HCl/HF mixed acid solution;

4) Carry out pre-dehydration and thermal drying treatment;

The selective emitter process includes:

1) placing the single-slot double-chip front side of the silicon wafer after the cleaning and texturing process on the front side, and carrying out boron doping on the back side of the battery in a boron tribromide atmosphere;

2) At the end of the boron diffusion, the temperature is lowered, and oxygen is introduced to oxidize the boron diffusion surface to form a borosilicate glass (BSG) layer;

3) The thinning process of the BSG formed on the back of the battery during boron diffusion is completed in the HF acid wet process equipment;

The process of preparing the deposition mask layer is to use PECVD to complete the deposition of the backside silicon nitride layer on the BSG layer after the thinning treatment in the selective emitter process;

The process for preparing the surface field includes:

1) The phosphorus-doped region is opened on the back of the cell by laser ablation, and the BSG layer and the silicon nitride layer on the BSG layer are removed;

2) The silicon on the surface of the window area is removed by 18%-20% alkali solution treatment, and the recombination rate of carriers introduced by the surface damage caused by laser ablation is reduced;

3) The silicon wafer is then placed in a single groove and a single wafer, and double-sided phosphorous doping is performed in a tube furnace to form a front surface field and a back surface field region at the same time;

4) placing the silicon wafer forming the back surface field region and the front surface field in an HF acid solution to perform a thinning treatment of phosphorus diffusion on the surface to form phosphosilicate glass (PSG);

The process of preparing the anti-reflection layer includes the following steps:

1) using the thinned silicon wafer to complete the deposition of the anti-reflection layer on the front side of the battery with PECVD equipment;

2) carrying out the deposition process of the anti-reflection layer on the back of the battery in PECVD with the silicon wafer that completes the deposition of the front anti-reflection layer;

The electrode fabrication process includes

1) The first burn-through slurry is printed on the silicon wafer after the preparation of the anti-reflection layer process is completed to form a point-break type secondary grid line silver, copper, silver-plated copper, nickel-plated copper, tin-plated copper or alloy slurry material;

2) printing the second line-type auxiliary grid line silver, copper, silver-plated copper, nickel-plated copper, tin-plated copper or alloy slurry on the silicon wafer that has completed the first printing of the burn-through slurry;

3) The third and fourth tracks are equally divided into step-by-step printing of insulating paste, and the purpose of secondary printing of insulating paste is to ensure good insulation between the main grid line and the boron-doped area and the auxiliary grid lines in the phosphorus-doped area;

4) Finally, the silicon wafer on which the fourth insulating paste has been printed is subjected to the fifth busbar silver-aluminum paste printing, which is used to derive the current generated by the battery;

Preferably, in the selective emitter process, the diffusion resistance of boron doping on the back of the battery is 130-155Ω·cm, and the diffusion temperature is 700-1100°C.

Preferably, in the selective emitter process, the temperature is lowered to 700-900° C. after the boron diffusion is completed.

Preferably, the deposition film thickness of the silicon nitride layer on the backside of the process of preparing and depositing the mask layer is 40-100 nm.

Preferably, in the process of preparing the surface field, about 4-7um of silicon at the surface of the substrate corresponding to the window region will be removed.

Preferably, in the process of preparing the surface field, the temperature for forming the back surface field region is 700-1100° C., and the square resistance is 100-200 Ω·cm.

Preferably, in the process of preparing the surface field, the diffusion resistance of the surface field before forming is 100-200 Ω·cm, and the diffusion temperature is 700-1100°C.

Preferably, in the process of preparing the anti-reflection layer, the refractive index of the anti-reflection layer deposited on the front side of the battery is 2.0-2.2, and the temperature is 300-600°C.

Preferably, in the process of preparing the anti-reflection layer, the refractive index of the anti-reflection layer on the back of the battery is 2.0-2.2, and the process temperature is 300-600°C.

The present invention is a preparation method of a full-suede IBC solar cell, which increases the light absorption rate of the front surface by moving the electrodes to the back surface, thereby increasing the short-circuit current. At the same time, the front surface and the back surface of the obtained battery are all suede surfaces, which greatly reduces the light reflectivity and further improves the light capture amount. Compared with the prior art, the present invention has the following advantages and positive effects:

1) Optimize the process plan to reduce the manufacturing cost;

2) The process is simple, reducing the probability of introducing defects;

3) It is convenient to analyze the source of the process section when the battery efficiency declines and defects occur.

Description of drawings

Figure 1 IBC battery structure diagram

Figure 2 IBC battery process flow chart

Detailed ways

Example

The present invention will be further described below in conjunction with the examples. The present invention includes the following contents, but is not limited to the following contents.

In order to solve the above-mentioned deficiencies of the prior art, the present invention provides a method for preparing a full-suede IBC solar cell, the steps of which are as follows:

(1) The cleaning and texturing include:

1) Place the N-type silicon wafer in NaOH and H2O2 solution to clean the mechanical damage layer and surface oil on the surface of the silicon wafer;

2) The surface texture treatment of silicon wafers is carried out in the mixed solution of NaOH and single crystal texturing additive;

3) Neutralize the NaOH solution on the surface of the silicon wafer, clean the metal ions and the oxide layer in the HCl/HF mixed acid solution;

4) Carry out pre-dehydration and thermal drying treatment;

(2) The preparation of the selective emitter includes:

1) placing the single-slot double-chip front side of the silicon wafer processed in step (1) on the front side, and carrying out boron doping on the back side of the battery in a boron tribromide atmosphere;

2) At the end of the boron diffusion, the temperature is lowered, and oxygen is introduced to oxidize the boron diffusion surface to form a BSG layer;

3) The thinning process of the BSG formed on the back of the battery during boron diffusion is completed in the HF acid wet process equipment;

(3) The deposition mask layer includes:

1) on the silicon wafer after thinning the BSG in step (2), use PECVD equipment to complete the deposition of the backside silicon nitride layer, and the film thickness control range is 40-120nm;

(4) The preparation of the surface field includes:

1) First, the phosphor-doped region is opened on the back of the cell by laser ablation, and the BSG layer and the silicon nitride layer on the BSG layer are removed;

2) Secondly, the silicon on the surface of the window area is removed by 18%-20% alkali solution treatment, so as to reduce the carrier recombination rate introduced by the surface damage caused by laser ablation;

3) The silicon wafer is then placed in a single groove and a single wafer, and double-sided phosphorous doping is performed in a tube furnace to form the front surface field and the back surface field area at the same time; finally, the silicon wafer with the surface field is completed in HF acid solution. Thinning treatment of PSG formed by surface phosphorus diffusion;

(5) The process for preparing the anti-reflection layer includes:

1) After the PSG is thinned in step (4), use PECVD to complete the deposition of the anti-reflection layer on the front side of the battery on the PSG, the refractive index is in the range of 2.0-2.2, and the process temperature is 300-600 ° C;

2) Secondly, the anti-reflection layer on the back of the battery is processed in PECVD, the refractive index range is 2.0-2.2, and the process temperature is 300-600 °C;

(6) The electrode manufacturing process includes five-step screen printing, specifically:

1) The first pass of printing burn-through paste to form point-breaking secondary grid line silver, copper, silver-plated copper, nickel-plated copper, tin-plated copper or alloy paste;

2) Silver, copper, silver-plated copper, nickel-plated copper, tin-plated copper or alloy paste for the second printed wire-type auxiliary grid line;

3) The third and fourth tracks are all printed with insulating paste step by step, and the purpose of secondary printing of insulating paste is to ensure good insulation between the main grid line and the auxiliary grid lines in the P+ area and the N+ area;

4) The fifth line simultaneously prints the positive and negative busbar silver-aluminum paste, which is used to derive the current generated by the battery;

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form or substance. It should be pointed out that for those skilled in the art, without departing from the method of the present invention, the Several improvements and supplements can be made, and these improvements and supplements should also be regarded as the protection scope of the present invention. All those skilled in the art, without departing from the spirit and scope of the present invention, can utilize the above-disclosed technical content to make some changes, modifications and equivalent changes of evolution, all belong to the present invention. Equivalent embodiments; at the same time, any modification, modification and evolution of any equivalent changes made to the above embodiments according to the essential technology of the present invention still fall within the scope of the technical solutions of the present invention.

Claims (9)

1. A preparation method of a full-suede IBC solar cell is characterized by comprising a cleaning and texturing process, a selective emitter process, a mask layer deposition process, a surface field preparation process, an antireflection layer preparation process and an electrode manufacturing process;

the cleaning and texturing process comprises the following steps:

1) placing the N-type silicon wafer in NaOH and H2O2 liquid to clean a mechanical damage layer and surface oil stains on the surface of the silicon wafer;

2) carrying out silicon wafer surface texturing treatment in a mixed solution of NaOH and a single crystal texturing additive;

3) neutralizing NaOH solution on the surface of the silicon wafer and cleaning metal ions and an oxide layer in HCl/HF mixed acid solution;

4) carrying out pre-dehydration and heat drying treatment;

the selective emitter process comprises:

1) placing the front sides of the single-groove double-piece silicon wafer treated by the cleaning and texturing process in a front-side-attached mode, and carrying out boron doping on the back side of the cell in a boron tribromide atmosphere;

2) after the boron diffusion is finished, cooling, introducing oxygen to oxidize the boron diffusion surface to form a BSG layer;

3) finishing the thinning treatment of BSG formed on the back of the battery during boron diffusion in HF acid wet equipment;

the process for preparing the deposition mask layer is to deposit a back silicon nitride layer on the BSG layer after thinning treatment in the selective emitter electrode process by PECVD;

the surface field preparation process comprises the following steps:

1) windowing a phosphorus doped region on the back surface of the battery by a laser ablation method, and removing the BSG layer and the silicon nitride layer on the BSG layer;

2) removing silicon on the surface of the windowing area by treating with 18% -20% alkali liquor;

3) then placing the single silicon wafer in the single groove, carrying out double-sided phosphorus doping in a tube furnace, and simultaneously forming a front surface field region and a back surface field region;

4) placing the silicon wafer with the back surface field region and the front surface field in HF acid solution for surface phosphorus diffusion to form PSG;

the process for preparing the antireflection layer comprises

1) Depositing an antireflection layer on the front side of the cell on the thinned silicon wafer by using PECVD equipment;

2) depositing the silicon wafer on which the front antireflection layer is deposited in a PECVD (plasma enhanced chemical vapor deposition) manner on the back antireflection layer of the cell;

the electrode manufacturing process comprises

1) Printing a first burn-through type slurry on the silicon wafer after the antireflection layer preparation process is completed to form a point-broken auxiliary grid line silver, copper, silver-plated copper, nickel-plated copper, tin-plated copper or alloy slurry;

2) printing a second linear auxiliary grid line silver, copper, silver-plated copper, nickel-plated copper, tin-plated copper or alloy slurry on the silicon wafer on which the first printing burn-through type slurry is finished;

3) step-sharing printing insulation slurry in the third and fourth steps;

4) and finally, printing a fifth main grid line silver-aluminum paste on the silicon wafer on which the fourth insulating paste is printed.

2. The method as claimed in claim 1, wherein in the selective emitter process, the diffusion sheet resistance of boron doping on the back surface of the cell is 130-155 Ω -cm, and the diffusion temperature is 700-1100 ℃.

3. The method as claimed in claim 1, wherein in the selective emitter process, the temperature is reduced to 700-900 ℃ after the boron diffusion is finished.

4. The method for preparing an all-matte IBC solar cell according to claim 1, wherein the thickness of the deposited silicon nitride layer on the back side of the process for preparing the deposition mask layer is 40-120 nm.

5. The method of claim 1, wherein about 4-7um of silicon at the surface of the window is removed during the surface field preparation process.

6. The method as claimed in claim 1, wherein in the surface field preparation process, the temperature for forming the back surface field region is 700-1100 ℃, and the sheet resistance is 100-200 Ω -cm.

7. The method as claimed in claim 1, wherein in the surface field preparation process, the diffusion sheet resistance of the front surface field is 100-200 Ω -cm, and the diffusion temperature is 700-1100 ℃.

8. The method as claimed in claim 1, wherein in the step of forming the antireflection layer, the refractive index of the antireflection layer deposited on the front surface of the cell is 2.0-2.2 at 300-600 ℃.

9. The method as claimed in claim 1, wherein in the step of preparing the antireflection layer, the refractive index of the antireflection layer on the back surface of the cell is 2.0-2.2, and the process temperature is 300-600 ℃.

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