Boron diffusion method for n-type silicon wafer, crystalline silicon solar cell and manufacturing method thereof

Abstract

The invention discloses a boron diffusion method of an N-type silicon chip, a crystalline silicon solar cell and a manufacturing method thereof. The boron diffusion method includes the following steps: in the deposition stage, the wet-etched silicon wafer is placed in a diffusion furnace to heat up to a predetermined deposition temperature, and a boron source, oxygen and nitrogen are introduced to deposit on the surface of the silicon wafer; stage, heat up the surface-deposited silicon wafer to a predetermined diffusion temperature, promote diffusion, and feed oxygen and nitrogen during the process of heating up and promoting diffusion; and the post-oxidation stage, cool down the diffused silicon wafer, and Oxygen and nitrogen are introduced into the process. The deposition and diffusion process reduces the concentration of boron atoms on the surface of the silicon wafer, reduces the surface recombination rate and lattice damage, controls the standard deviation of square resistance (STDEV) at about 2.0, improves the uniformity of boron diffusion square resistance, and improves the The conversion efficiency of the battery also reduces the boron source consumption, avoids the generation of excessive borosilicate glass (BGS), and saves costs.

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 prod...

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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 boron source consumption 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 thicker 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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