Phosphorus diffusion method for crystalline silicon solar cells

Abstract

The present invention discloses a phosphorus diffusion method of a crystalline silicon solar cell. The method comprises the steps of (1) entering into a boat, (2) adjusting temperature to be below 800 DEG C, introducing nitrogen carrying phosphorus source and dry oxygen, and forming a silicon dioxide layer containing phosphorus, (3) carrying out low temperature diffusion, (4) raising the temperature in a furnace and pushing with the rise of the temperature, (5) carrying out first time of high temperature diffusion, (6) raising the temperature in the furnace and pushing with the rise of the temperature, (7) carrying out second time of high temperature diffusion, (8) reducing the temperature in the furnace and pushing with the decrease of the temperature, and (9) reducing the temperature and going out of the boat, and completing a diffusion process. According to the method, an oxidation gettering effect is enhanced and the concentration gradient of the phosphorus doping is controlled, the separation and collection of carriers are facilitated, the open circuit voltage is raised, the temperature difference in a cooling process is controlled, and a crystal boundary gettering effect is enhanced.

Description

technical field [0001] The invention relates to a phosphorus diffusion method for a crystalline silicon solar cell, which belongs to a diffusion junction process for manufacturing a solar cell and belongs to the technical field of solar cells. Background technique [0002] Conventional fossil fuels are increasingly depleted. Among all sustainable energy sources, solar energy is undoubtedly the cleanest, most common and most potential alternative energy source. At present, among all solar cells, crystalline silicon solar cells are one of the solar cells that have been widely commercialized. This is due to the extremely abundant reserves of silicon materials in the earth's crust. Cells have excellent electrical and mechanical properties, therefore, crystalline silicon solar cells occupy an important position in the field of photovoltaics. [0003] The manufacturing process of crystalline silicon solar cells widely used at present has also been standardized. The main steps are...

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Problems solved by technology

[0005] However, practical applications have found that the above-mentioned process has the following problems: (1) in the step of forming a silicon dioxide layer by passing oxygen at a low temperature, oxygen and nitrogen are introduced to form a silicon dioxide layer on the surface of a silicon wafer at a low temperature, which has the effect of improving the uniformity of diffusion. However, under low temperature conditions, oxygen reacts with P-type silicon to form silicon dioxide at a slower rate, resulting in a thinner silicon dioxide layer (currently generally only about 60 nm), resulting in a diffused The minority carrier lifetime is low, and the conversion efficiency of solar cells is low; (2) The existing process adopts low-temperature source deposition and high-temperature diffusion, which has poor segregation and gettering effects, which is not conducive to the collection of photogenerated carriers. lower open circuit voltage

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