Method for removing foreign matters on surface of silicon melt and growth method of monocrystalline silicon

Abstract

The invention discloses a method for removing foreign matters on the surface of a silicon melt and a growth method of monocrystalline silicon, and belongs to the technical field of monocrystalline silicon growth. The method for removing the foreign matters on the surface of the silicon melt comprises the following steps: forming an approximately belt-shaped dark color area on the surface of the silicon melt before welding a seed crystal and the silicon melt, continuously monitoring the surface of the silicon melt, and if the foreign matters exist on the surface of the silicon melt, moving at least part of the foreign matters on the surface of the silicon melt to the dark color area and to the wall of a crucible along the dark color area. The device can effectively remove foreign matters from the surface of the silicon melt.

Description

technical field [0001] The present application relates to the technical field of single crystal silicon growth, in particular, to a method for removing foreign matter on the surface of silicon melt and a method for growing single crystal silicon. Background technique [0002] The process flow of Czochralski growing monocrystalline silicon generally includes: melting, chemical material, welding, seeding, necking, shouldering, shoulder turning, equal diameter, finishing and other processes. Generally speaking, in the seeding stage, the crystal is extracted by rotation Then the crystal growth process started. As we all know, impurities have an important impact on the growth and quality of crystals. In order to successfully grow single crystal silicon, impurities in the furnace should be avoided as much as possible. [0003] Generally speaking, the production of impurities will be minimized by using high-quality quartz crucibles and polysilicon raw materials. However, it is un...

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Problems solved by technology

However, it is unavoidable that a small amount of oxygen impurities will still dissolve from the side wall of the quartz crucible and enter the silicon melt, and 95% of the oxygen atoms entering the melt will volatilize from the melt surface in the form of SiO gas. Part of it enters the crystal by segregation phenomenon

[0004] The inventor of the present application found during production that oxygen impurities or other foreign matter in the form of solid particles occasionally appear on the surface of silicon melt for some reason. Once it appears and is not removed in time, it will often lead to failure to successfully produce monocrystalline silicon, which will lead to a sharp drop in the yield of monocrystalline silicon

The main reason is that the mechanical strength of silicon single crystal is not high. If there are solid particle impurities such as oxides on the surface of silicon melt, when the single crystal silicon grows, it will be affected by the convection in the silicon melt and move to the growth of single crystal silicon. Near the solid-liquid interface, and collide with the single crystal, the impact will exceed the critical shear stress (CRSS) of the crystal, so that the single crystal structure cannot be maintained, and the single crystal silicon will be broken or broken.

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