Phosphorus-hydrogen annealing pretreatment method for casting single-crystal or polycrystal silicon wafers

Abstract

The invention relates to a phosphorus-hydrogen annealing pretreatment method for casting single-crystal or polycrystal silicon wafers, which comprises the following steps of A, pickling, B, depositing PSG at high temperature, C, primary impurity removal, and D, high-temperature hydrogen annealing. The invention aims to provide a phosphorus-hydrogen annealing pretreatment method for casting single-crystal or polycrystalline silicon wafers, which is suitable for effective passivation of the cast single-crystal or polycrystalline silicon wafer, and can release metal impurities from crystal defects such as dislocation and grain boundary, reduce in-vivo recombination of carriers, improve the overall passivation level and in addition, external diffusion of oxygen in silicon is facilitated, grain dislocation is reformed, and lattice defects are reduced.

Description

technical field [0001] The invention relates to the field of solar cells, in particular to a phosphor-hydrogen annealing pretreatment method for cast single crystal or polycrystalline silicon wafers. Background technique [0002] As a new energy source, solar energy has become a vigorously developed industry in the 21st century. The research and development and production of solar cells are mainly carried out around the direction of cost reduction and efficiency increase. Improving the conversion efficiency of solar cells is the foundation of the development of solar energy business. Reducing the production cost of solar cells is the foundation of expanding the solar energy business and the prerequisite for mass production. condition. [0003] Silicon wafers are the carrier used in the production of silicon-based solar cells, generally divided into monocrystalline silicon wafers, cast monocrystalline silicon silicon wafers and polycrystalline silicon wafers. Using low-cost...

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Problems solved by technology

[0004] But casting single crystal, due to the characteristics of the casting process, there are both single crystal regions and polycrystalline regions on the same silicon wafer surface, so there are generally disadvantages such as dislocations, small-angle grain boundaries, and high defect density inside the silicon wafer. It has brought certain difficulties to the passivation of solar cells. The existing fabrication methods of cast monocrystalline silicon heterojunction solar cells are similar to the traditional heterojunction solar cell fabrication processes, even if high-quality surface cleaning and surface passivation are applied. The overall minority carrier life is still not high, which affects the conversion efficiency of the final battery

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