Low-pressure diffusion technology for crystalline silicon cell

Abstract

The invention discloses a low-pressure diffusion technology for a crystalline silicon cell. The technology comprises the following steps: (1) a high-temperature oxidation before diffusion; (2) a low-pressure diffusion, namely preparing a PN knot by a sub-step diffusion method; and (3) annealing, namely changing internal pressure to remove impurities. According to the low-pressure diffusion technology, the uniformity between diffusion sheets can be improved; the temperature of a temperature zone in a fire hole is lowered, namely the temperature uniformity of various temperature zones of a diffusion tube is improved; the problem of a great fluctuation of sheet resistance of the fire hole of a diffusion furnace is solved; the service lifetime of a vacuum pump is prolonged; and the production cost of a diffusion procedure is reduced.

Description

technical field [0001] The invention belongs to the field of diffusion processing in the preparation process of crystalline silicon batteries, and in particular relates to a diffusion process capable of improving the uniformity between diffusion sheets of a low-voltage diffusion furnace and the stability of battery performance. Background technique [0002] In terms of the industrialization of crystalline silicon cells, high-temperature diffusion methods are usually used to prepare PN junctions, and the industrial preparation of high-resistance emitters with good inter-chip and intra-chip uniformity is an important way to improve battery conversion efficiency and electrical performance stability. The optimization space of the diffusion process can be improved as a whole, and the number of battery efficiency bins can be reduced. With the continuous development of high square resistance paste, improving the square resistance value of the emitter, the consistency of the longitu...

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Problems solved by technology

However, the smaller the air pressure value, the more stringent the requirements for the vacuum pump, which will reduce the service life of the vacuum pump

If only the temperature compensation method is used to solve the problem of the uniformity of the diffusion square resistance between the entire tube slices, due to the low concentration of phosphorus source, the temperature of the tube mouth is usually higher than that of the tube tail by more than 20°C, and the temperature from the furnace tail to the furnace mouth presents a gradient distribution. The heat disturbance in the furnace tube makes it difficult to improve the uniformity of the longitudinal concentration distribution of diffusion doping between the wafers, which seriously restricts the doping uniformity in the silicon wafer, which is not conducive to the improvement of the subsequent process of the battery

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