Method for drawing large-size low-oxygen silicon single crystal by RCZ method

Abstract

The invention discloses a method for drawing a large-size low-oxygen silicon single crystal by an RCZ method. According to the method, a water and electricity treatment part of an original solar single crystal furnace is slightly improved, in other words, during normal operation, a flow meter feeds back water inlet flow information of a water cooling screen, the system controls the opening degreeof the adjusting valve according to the flow set by parameters, the growth speed of the single crystal and the flow of the water cooling screen are controlled in a linked mode in the whole crystal growth process, and the whole production process of the single crystal is effectively controlled. When the water outlet temperature of the water cooling screen is too high, the automatic switch valve isautomatically opened; when the water outlet temperature of the water cooling screen is too high and the automatic switch valve cannot be opened, the manual ball valve can be manually opened to supplywater to the water cooling screen. Through the improvement, the oxygen content of the obtained wafer silicon is reduced by about 1.0 PPM, the wire breakage rate is reduced by 5%, and the method has agood market application prospect.

Description

technical field [0001] The invention relates to the technical field of silicon single crystal growth, in particular to a method for drawing a large-size low-oxygen silicon single crystal by an RCZ method. Background technique [0002] The RCZ method (multiple loading crystal pulling technology) is becoming more and more mature for pulling solar-grade single crystals, and the furnace body is getting bigger and bigger. The size of the single crystals being drawn is also getting bigger and bigger, and the quality requirements are also getting higher and higher. high. When the size of the furnace body and the single crystal becomes larger, it takes longer to stabilize the temperature of the silicon liquid, resulting in a relatively poor stability of the oxygen content of the single crystal. In order to meet the production needs, it is urgent to study a process improvement treatment in order to reduce the oxygen content in single crystal silicon. Contents of the invention ...

AI Technical Summary

Problems solved by technology

[0003] Aiming at the problem that when the size of the furnace body and the single crystal is getting larger and larger, the temperature stabilization time of the silicon liquid is also getting longer and longer, resulting in relatively poor stability of the oxygen content of the single crystal, the present invention provides a large-size Low-oxygen silicon single crystal method, after the method is improved on the existing equipment, the formation rate of the obtained silicon single crystal is high, and the oxygen content is also reduced accordingly

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