Preparation method of selective emitter structure in lightly doped region with low surface concentration

Abstract

A method for manufacturing a selective emitter structure with low surface concentration and a soft doped zone includes the steps that (1) the surface of a substrate to be prepared is corroded and cleaned, and the surface of the substrate is completely dried after cleaning; (2) the clean substrate prepared in the step (1) is soaked in a solution with high oxidability to carry out wet chemical oxidation on the surface of a silicon wafer, and then the surface of the substrate is completely dried; (3) a microcosmic salt aqueous solution of 0.5-20% is deposited on the surface of the substrate in a spin coating and spraying mode, and then the surface of the substrate is dried; (4) phosphorus ink or silicon ink is deposited on an electrode area on the surface of the substrate coated with a phosphorus source in the step (3) in a screen printing mode, and then the surface of the substrate is dried; (5) the temperature of a diffusion furnace rises, nitrogen is introduced into a diffusion quartz tube, when the temperature reaches 780-890 DEG C, the clean substrate prepared in the step (4) is placed into a constant-temperature area of the diffusion quartz tube, a fire door of the diffusion furnace is sealed, and after the temperature of the diffusion furnace is stable, oxygen is introduced into the diffusion quartz tube; (6) the substrate is taken out and cooled after the diffusion process is over.

Description

technical field [0001] The invention relates to a method for preparing a selective emitter structure of a low surface concentration lightly doped region of a crystalline silicon solar cell. Background technique [0002] Crystalline silicon solar cells still dominate the photovoltaic market, and low cost and high conversion efficiency are still the two major goals of crystalline silicon solar cell technology breakthroughs and production innovations. In the continuous progress of solar cell development and production technology, selective emitter structure solar cells are favored due to their low series resistance and excellent blue light response, which has aroused the interest of many researchers and producers. The characteristic of this selective emitter structure solar cell is that the emitter is composed of a heavily doped emitter region and a lightly doped emitter region, so it is called a selective emitter structure. Among them, the heavily doped emitter is also called...

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Problems solved by technology

Their common feature is that phosphorus oxychloride is used for high-temperature diffusion. In addition to the above shortcomings, the main problems of various implementation methods are: (1) The etching back process needs to be protected by a mask, and the process is complicated and difficult to control. Not only the preparation The cycle is long, and the preparation cost is increased; (2) In the current methods for the preparation of selective emitter structures, phosphorus oxychloride liquid sources are used to achieve high-temperature diffusion doping, which is an expensive and non-environmentally friendly (3) For the doping achieved by the diffusion of phosphorus oxychloride liquid source, its surface concentration can reach a higher surface concentration at a general diffusion temperature, at 10 20 cm -3 The above (edited by the Education Office of Semiconductor Physics, Department of Physics, Xiamen University, Principles of Semiconductor Device Technology, published by People’s Education Press), is easy to form a diffusion dead layer on the surface of silicon wafers, which inhibits the blue light response of lightly doped regions of selective emitter structure solar cells, It is not conducive to further improving the utilization of incident light, nor is it conducive to further improving the conversion efficiency of selective emitter structure solar cells

In short, in the various ways to realize the preparation of selective emitter structure solar cells at present, none of them avoid the participation of high temperature diffusion of phosphorus oxychloride liquid source. 20 cm -3 Above, the dead layer on the surface of the lightly doped region is formed, which inhibits the blue light response of the solar cell and reduces the further improvement of the conversion efficiency of the selective emitter structure solar cell.

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