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Additives for Alkaline Polishing of Single Crystal Silicon Chips and Their Applications

A silicon wafer alkali and additive technology, applied in the direction of single crystal growth, single crystal growth, crystal growth, etc., can solve the problems of poor stability, pyramid residue, low reflectivity, etc., achieve electrical performance gain, improve efficiency, high reflectivity Effect

Active Publication Date: 2022-05-17
CHANGZHOU SHICHUANG ENERGY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Alkali polishing is a relatively common technical means at present, but there are often the following problems in alkali polishing: 1) Pyramids will remain if the alkali polishing is not thorough; 2) The reflectivity of alkali polishing is difficult to improve, and the stability is poor; 3) Alkali polishing The resulting tower base is smaller
[0004] At present, additives are also used in the polishing liquid to improve the above-mentioned alkali polishing problems, but the existing alkali polishing additives mainly use polishing agents, chelating agents, and protective agents, and there are still the following problems: 1) The alkali polishing additives have poor stability and the validity period is 3 Within one month; 2) The tower base formed by polishing is small; 3) The flatness of the polished surface is poor, and the reflectivity is low

Method used

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  • Additives for Alkaline Polishing of Single Crystal Silicon Chips and Their Applications
  • Additives for Alkaline Polishing of Single Crystal Silicon Chips and Their Applications
  • Additives for Alkaline Polishing of Single Crystal Silicon Chips and Their Applications

Examples

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Effect test

Embodiment 1

[0041] Get 2.5L alkali throw tank, add 2L water, raise temperature to 65 ℃, then add 100mL of 48% NaOH, add 30ml of additive of the present invention after temperature stabilizes (formulation is: 0.05wt% ethyl vanillin , 1wt% polyphosphate, 3wt% disodium tetraacetate, 0.08wt% benzotriazole, and the balance is deionized water); after stirring evenly, remove the silicon wafer with PSG, and place it in NaOH and hydrogen peroxide at 45°C Pre-clean in the tank for 2 minutes. After the pre-cleaning is completed, put it in the water tank for 2 minutes, then put the silicon wafer in the alkali polishing tank for polishing for 4 minutes, and then put it in the water tank for 2 minutes after polishing. The alkali polishing etching process is completed.

Embodiment 2

[0047] Get 2.5L alkali throw tank, add 2L water, raise temperature to 65 ℃, then add 100mL of 48% NaOH, add 30ml of additive of the present invention after temperature stabilizes (formulation is: 0.05wt% ethyl vanillin , 1wt% polyphosphate, 3wt% disodium tetraacetate, 0.08wt% benzotriazole, and the balance is deionized water) to prepare a polishing liquid; place the polishing liquid for use after three months. Stir the polishing solution evenly, remove the PSG silicon wafer, and perform a pre-cleaning in a tank of NaOH and hydrogen peroxide at 45°C for 2 minutes. After the polishing is completed, put it into the water tank for cleaning for 2 minutes, and the alkali polishing etching process is completed.

Embodiment 3

[0052] Get 150L of alkali throw tank, add 140L of water, temperature is raised to 65 ℃, then add 6L of 48% NaOH, after the temperature stabilizes, add 3.5L of the additive of the present invention (formulation is: 0.05wt% ethyl vanillin , 1wt% polyphosphate, 3wt% disodium tetraacetate, 0.08wt% benzotriazole, and the balance is deionized water); after stirring evenly, 1200 pieces of silicon wafers without PSG were polished. Pre-clean in the tank of NaOH and hydrogen peroxide for 2 minutes. After the pre-cleaning is completed, put it in the water tank for 2 minutes, then put the silicon wafer in the alkali polishing tank for polishing for 4 minutes, and then put it in the water tank for 2 minutes after polishing. The alkali polishing etching process is completed. ; Then enter the follow-up solar cell preparation process to obtain finished solar cell sheets.

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Abstract

The invention discloses an additive for single crystal silicon wafer alkali polishing, the mass percent of each component is: polishing component 0.01%-1%, dispersant 1%-3%, anti-sedimentation agent 1%-5% , Protective agent 0.05% ~ 0.1%, the balance is deionized water. Adding the additive of the present invention to the polishing solution for alkali polishing of monocrystalline silicon wafers can make the back polishing surface of silicon wafers have high flatness, low specific surface area, no traces, mirror effect in appearance, high reflectivity, and ultimately improve battery efficiency 0.03%~0.05%, which meets the polishing requirements of PERC cells.

Description

technical field [0001] The invention relates to the field of photovoltaics, in particular to an additive for single crystal silicon wafer alkali polishing and its application. Background technique [0002] At present, the etching and polishing process of solar cells is a crucial step in the manufacturing process of high-efficiency solar cells. It has a significant impact on the electrical properties of finished cells and the EL yield rate. The uniformity of the reflectivity of the silicon wafer after etching determines the The uniformity of the back passivation coating, the uniformity of the coating determines the uniformity of the laser opening rate and size; therefore, etching plays a key role in the production process of PERC cells (Passivated emitter rear contact solar cells) pivotal role. [0003] Alkali polishing is a relatively common technical means at present, but there are often the following problems in alkali polishing: 1) Pyramids will remain if the alkali poli...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C30B33/10C30B29/06C09G1/04
CPCC30B33/10C30B29/06C09G1/04Y02P70/50
Inventor 杨勇章圆圆陈培良
Owner CHANGZHOU SHICHUANG ENERGY CO LTD
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