Method and heater for improving quality of monocrystal silicon grown by Czochralski method

Abstract

The invention discloses a method and a heater for improving quality of monocrystal silicon grown by Czochralski method. The method includes putting raw silicon into a crucible of a crystal furnace; heating the crucible to melt the raw silicon in the crucible by the heater and keeping a melt in a molten state; soaking a rod-shaped seed crystal in a solution; injecting inert gas to the liquid level of the melt and controlling furnace pressure; rotating the crucible and lifting the rod-shaped seed crystal reversely rotating relative to the crucible to obtain a cylindrical monocrystal silicon crystal, and controlling heating quantity along the depth direction of the crucible during crystal pulling to enable the temperature gradient of the melt from the growth interface to the bottom of the crucible to decrease. The heater is used for implementing the method. The method and the heater have the advantages that heat convection is reduced effectively, microdefects and deleterious impurities in the monocrystal silicon are reduced, the monocrystal silicon with low defects, ultralow oxygen and high minority carrier lifetime is obtained, cost is low and easiness in implementation is achieved.

Description

technical field [0001] The invention relates to the Czochralski method single crystal silicon growth technology, in particular to a method for improving the quality of the Czochralski method grown single crystal silicon and a heater. Background technique [0002] Czochralski single crystal growth technology (Czochralski, CZ method) is to put raw silicon into a quartz crucible, heat and melt in a single crystal furnace, and then immerse a rod-shaped seed crystal (seed crystal) into the melt. At a suitable temperature, the silicon atoms in the melt will form regular crystals on the solid-liquid interface along the silicon atom arrangement structure of the seed crystal, becoming a single crystal. Slightly rotate the seed crystal upwards, and the silicon atoms in the melt will continue to crystallize on the previously formed single crystal, and continue its regular atomic arrangement structure. If the entire crystallization environment is stable, crystallization can be formed r...

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Problems solved by technology

[0008] Although an appropriate amount of oxygen in semiconductor single crystal silicon forms oxygen precipitates during device processing to have an internal gettering effect, which can improve the performance of the device, but a large amount of oxygen precipitates formed by excessive oxygen content and induced secondary defects Reaching a certain size will seriously affect the performance of the device. In the presence of high defect density and high oxygen at the same time, it is easier to form vortex defects and OISF rings that can be observed with the naked eye, leading to the scrapping of the device. Therefore, it is necessary to reduce the single crystal Oxygen content in silicon

In solar monocrystalline silicon, although the processing temperature of the cell is not high, the time is not long, and the amount of oxygen precipitation is small, the initial stage of oxygen precipitation has a great impact on the minority carrier lifetime of the material. The combination of high-density defects and high oxygen , resulting in a sharp drop in the life expectancy of the few births, resulting in black-hearted inefficiency, and seriously affecting product quality

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