Method for growing cz si crystal in total nitrogen environment

Abstract

The invention provides a method for growing a cz si crystal in a total nitrogen environment. The method comprises the steps of melting, temperature stabilizing, seeding, shouldering, shoulder circuit,diameter equalizing, closing and the like, the method is characterized in that the diameter equalizing step is divided into three stages, wherein the second stage is diameter equalizing is conductedto reach 200mm to 2000mm, the injected gas is all nitrogen, and the growth speed of the crystal is higher than 84mm/hr. The method has the beneficial effects that the fraction rate of a battery pieceprepared from cz si crystals which are manufactured by adopting the production method is reduced by 2%, the lumen depreciation is lower than 1.7%, the conversion rate is higher than 21% and conforms the industry standard, the nitrogen crystal pulling crystallization rate is improved while the production cost is reduced, the using requirement is met, and the cost is reduced by at least 6.25%.

Description

technical field [0001] The invention belongs to the technical field of single crystal silicon production, and in particular relates to a method for growing Czochralski silicon single crystal with all nitrogen. Background technique [0002] In the process of monocrystalline silicon production, during the crystal growth process, protective gas needs to be introduced to remove impurities in the production process and reduce the temperature of single crystal. Due to the relatively high price of argon gas, the cost of pulling single crystal is greatly increased. Therefore, in the production process of monocrystalline silicon, nitrogen is used instead of argon as a protective gas, or a mixed gas of argon and nitrogen is used as a protective gas. In the prior art, there are the following problems: [0003] 1. Due to the use of nitrogen instead of argon as a protective gas, there is a reaction between nitrogen and silicon in the melt, which affects the quality of the product; [00...

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Problems solved by technology

[0003] 1. Due to the use of nitrogen instead of argon as a protective gas, there is a reaction between nitrogen and silicon in the melt, which affects the quality of the product;

[0004] 2. Since the mixed gas of argon and nitrogen is used as the protective gas, in the process of gas control, the inaccurate control of nitrogen gas source and argon gas source leads to a further increase in cost, and the product quality cannot be effectively improved;

[0005] 3. In the process of monocrystalline silicon production, due to the excessive amount of nitrogen gas, it is easy to react with crystalline silicon to form silicon nitride impurities, which will cause crystalline silicon to break

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