Boron diffusion method of N type silicon chip, crystalline silicon solar cell and manufacturing method of crystalline silicon solar cell

Abstract

The invention discloses a boron diffusion method of an N type silicon chip, a crystalline silicon solar cell and a manufacturing method of the crystalline silicon solar cell. The boron diffusion method comprises the following steps of a deposition stage: placing the silicon chip subjected to wet etching into a diffusion furnace, and then introducing nitrogen, oxygen and a boron source for depositing the surface of the silicon chip; a diffusion stage: raising the temperature of the silicon chip with the surface being deposited to a preset temperature for promoting the diffusion of boron; a temperature dropping stage: dropping the temperature of the silicon chip with the boron being diffused, and introducing nitrogen in the temperature dropping process to obtain the silicon chip with the boron being diffused. After the deposition diffusion process disclosed by the invention is adopted, the concentration of boron atoms on the surface of the silicon chip is reduced, the recombination rate and the lattice damage of the surface are reduced, the STDEV (standard deviation) is controlled to be about 2.0, the sheet resistance uniformity of boron diffusion is improved, the battery conversion efficiency is improved, the consumption of boron sources is also reduced, BGS (borosilicate glass) is prevented from being excessively generated, and the cost is reduced.

Description

technical field [0001] The invention relates to the technical field of solar cell manufacturing, in particular to a boron diffusion method for an N-type silicon wafer, a crystalline silicon solar cell and a manufacturing method thereof. 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, 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. With excellent electrical and mechanical properties, silicon solar cells occupy an important position in the field of photovoltaics. Therefore, developing cost-effective silicon solar cells has become one of the main research directions of photovoltaic companies in various countries. [0003] In the prep...

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Problems solved by technology

However, the high-temperature deposition and high-temperature diffusion methods are complex and difficult to control, and the single-tube production capacity is low. The output of each furnace tube is only 80%, and the consumption of boron source is relatively large. The excess boron source reacts with the quartz furnace tube to form A large amount of borosilicate glass (BGS) not only seriously corroded the diffusion furnace and other equipment, but also caused serious waste of boron source

The most important thing is that the uniformity of the diffusion square resistance obtained by the high-temperature deposition and high-temperature diffusion process is poor, and its standard deviation (STDEV) is above 4.0, so that the p-n junction is not uniform, and the built-in electric field strength formed has a great influence on the minority current carrying capacity. The migration speed of electrons is affected, and a thick boron-rich layer (SiB compound) is produced on the surface of the silicon wafer, which is not easy to etch in the subsequent wet chemical reaction, severely destroys the surface lattice of the silicon wafer, and increases the surface recombination rate. Reduce the lifetime of minority carriers and seriously affect the conversion efficiency of the battery

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