Crystalline silicon diffusion process for realizing deep-junction and low-surface concentration

Abstract

The invention discloses a crystalline silicon diffusion process for realizing the deep-junction and low-surface concentration. During the diffusion process, the doping treatment is carried out on thecrystalline silicon in a diffusion furnace. The diffusion process comprises the following steps of inflating, keeping the pressure constant, putting a boat, heating, keeping the temperature constant,oxidizing, pre-diffusing, carrying out heating distribution, carrying out first-time constant-temperature distribution, carrying out diffusion, carrying out second-time constant-temperature distribution, cooling, re-inflating and taking the boat. According to the diffusion process disclosed by the invention, the problem of diffusion distribution nonuniformity can be well solved. Meanwhile, low-surface-concentration deep junctions can be better made and the square resistance can be made higher. The surface damage can be effectively improved and repaired. The electric performance can be improved.

Description

technical field [0001] The invention belongs to the production and manufacture of batteries, in particular to a crystalline silicon diffusion process for realizing deep junction and low surface concentration, and belongs to the field of photovoltaics. Background technique [0002] In the current solar cell manufacturing industry, diffusion is called the heart of the solar cell. The most commonly used method is to dope the silicon wafer in a tubular diffusion furnace to form a PN junction, and the quality of the PN junction directly affects the overall quality of the cell. Photoelectric conversion efficiency; therefore, the study of tube-type diffusion furnace tube technology is the focus of the photovoltaic industry to improve the conversion efficiency of crystalline silicon solar cells, but the current normal-pressure tube diffusion furnace will cause some unavoidable defects due to its structural and sealing problems : 1. The phosphorus source on the furnace tube structure...

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Problems solved by technology

[0002] In the current solar cell manufacturing industry, diffusion is called the heart of the solar cell. The most commonly used method is to dope the silicon wafer in a tubular diffusion furnace to form a PN junction, and the quality of the PN junction directly affects the overall quality of the cell. Photoelectric conversion efficiency; therefore, the study of tube-type diffusion furnace tube technology is the focus of the photovoltaic industry to improve the conversion efficiency of crystalline silicon solar cells, but the current normal-pressure tube diffusion furnace will cause some unavoidable defects due to its structural and sealing problems : 1. The phosphorus source in the furnace tube structure is carried into the furnace mouth by purging nitrogen from the tail of the furnace tube, and the gas distribution concentration is uneven; 2. The cells are sent into the furnace tube from the furnace mouth, and the temperature of the furnace mouth There will be a large difference in temperature; 3. Due to the more or less air leakage at the mouth of the conventional furnace tube, the uniformity and stability of the furnace mouth position will be poor; 4. When the temperature changes, the heating or cooling of different temperature zones will be different. There are asynchronous phenomena, which lead to differences in the square resistance of each temperature zone; the above-mentioned situation finally affects the uneven doping inside the crystalline silicon after the diffusion process. At present, the gradual rise of low-pressure diffusion furnaces in the industry can better form a uniform gas distribution. The overall square resistance can be made relatively high; in addition, many slurries on the market are suitable for low surface doping concentration, and the positive electrode screen is also developing in the direction of dense grid, which can be reasonably adapted to high surface concentration and deep junction. square resistance process, so this research has great prospects

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