Diffusion process of crystalline silicon solar cell

Abstract

The invention discloses a diffusion process of a crystalline silicon solar cell and mainly relates to preparation of a P-N junction by a liquid phosphorus source diffusion method during the production process of the crystalline silicon solar cell. The diffusion process is characterized in that a small amount of oxygen is firstly introduced during the heating process in a diffusion process step after feeding of a boat, and a silicon dioxide thin layer is formed, so that phosphorus atoms deposited on the surface of a silicon chip can only be diffused and enter the silicon chip after passing through a thin film of the silicon dioxide layer, and then the uniform diffusion effect can be realized; then high-temperature source introduction deposition is performed, so that a metal precipitate and a metal complex can be rapidly and effectively dissolved; cooling is further performed, only nitrogen is introduced, and source supplementation secondary low-temperature source introduction deposition is further performed, so that the driving force for absorbing impurities is greatly increased; and propelling and cooling are finally performed. By adopting the process disclosed by the invention, the photoelectric conversion efficiency of the solar cell can be effectively upgraded, the production time is greatly shortened, the production productivity is upgraded, the using quantity of phosphorus sources is saved, and the production cost is reduced; and furthermore, the process is simple and feasible, and additional process steps and materials are not required.

Description

technical field [0001] The invention relates to the field of crystalline silicon solar cell production, in particular to a crystalline silicon solar cell diffusion process. Background technique [0002] The most important characteristic of a crystalline silicon cell is its p-n junction. Although other characteristics of the cell will also affect the conversion efficiency, the p-n junction is the basic function of the cell. Diffusion is to generate p-n layers with different conductivity types on a base material. It is the core process in the battery manufacturing process and the heart of the battery sheet. [0003] In the current industrial production, there are three main ways to form the p-n layer: 1. Liquid source diffusion, at a certain temperature (>600°C) phosphorus oxychloride (POCl 3 ), oxygen reacts with silicon wafers to form phosphorus atoms for diffusion; 2. Solid source diffusion, boron nitride wafers are pre-passed with oxygen at the diffusion temperature fo...

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Problems solved by technology

[0006] At present, in the production of polycrystalline silicon cells, the liquid phosphorus source method is used to diffuse the P-N junction. 3 , O 2 and N 2 The main purpose of the deposition step is to form a mixture of phosphosilicate glass and phosphorus atoms on the surface of the silicon wafer through reaction, so as to prepare for the uniform entry of phosphorus atoms into the silicon wafer in the next step, but a single long-term high-temperature process will not only cause damage to the surface of the silicon wafer, It is also not conducive to the replacement of impurities in crystalline silicon; and polysilicon is diffused unevenly due to structural defects such as micro-defects, which ultimately affects the conversion efficiency of the cell

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