Crystal wafer and diffusion method thereof

Abstract

The invention discloses a diffusion method of a crystal wafer, which comprises the following steps that (1) the crystal wafer is made into wool and cleaned; (2) constant source diffusion is carried out, the atmosphere in a furnace comprises nitrogen, oxygen and pure nitrogen which carry diffusion sources, and the flow of the nitrogen, the oxygen and the pure nitrogen which carry the diffusion sources remains unchanged during a diffusion process; (3) impurity glass is removed, and cleaning is carried out; (4) limited source diffusion is carried out, only the nitrogen and the oxygen are fed in during the diffusion process, and the flow of the nitrogen and the oxygen remains unchanged; (5) diffusion is over, and the wafer is taken out; the surface doping concentration of the wafer is 1*1020atom / cm<3> to 5*1020atom / cm<3>; and the depth of a PN junction is 0.5mum to 1mum. According to the diffusion method, the 'dead-layer' effect caused by high surface doping concentration is effectively reduced, the auger recombination of surface photon-generated carrier is reduced, and the minority carrier lifetime is prolonged.

Description

technical field [0001] The invention relates to a crystalline silicon wafer and a diffusion method thereof. The crystalline silicon wafer can be used to prepare solar cells, belonging to the field of solar cells. Background technique [0002] Conventional fossil fuels are being exhausted day by day. Among the existing 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. , has excellent electrical and mechanical properties. Therefore, crystalline silicon solar cells occupy an important position in the field of photovoltaics. [0003] At present, the conventional production process of crystalline silicon solar cells is to start from crystalline silicon wafers and carry out texturing,...

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Problems solved by technology

[0006] However, the first method will increase the operation steps, increase the complexity of the process, relatively increase the production cost, and the uniformity is difficult to guarantee

The second method is mainly to prepare shallow junction cells by adjusting a diffusion process to reduce the depth of the PN junction (the junction depth is generally about 0.3 microns), but in order to ensure a certain square resistance value, this method requires higher surface doping impurity concentration, so the existence of "dead layer" cannot be really avoided, and at the same time, the process of this method is difficult and difficult to implement

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