Method for preparing sintering-free coating of polycrystalline silicon ingot crucible

Abstract

The invention discloses a method for preparing a sintering-free coating of a polycrystalline silicon ingot crucible. The method comprises the following steps: after uniformly mixing silica sol with water, adding silicon nitride and nanosilicon dioxide, and stirring uniformly to obtain a slurry; polishing the inner wall of the crucible with a scouring pad, blowing with compressed air after polishing, then preheating the crucible, and raising the corner temperature of the crucible to 70-80 DEG C; spraying the inner wall of the crucible with the slurry, during spraying, controlling the corner temperature of the crucible at 60-70 DEG C and spraying thickness at 0.8-0.9mm, and after spraying, baking the crucible at 60-70 DEG C for 20-30 minutes. Compared with the prior art, the method can prevent the coating from peeling and dusting, and meanwhile, avoids the crack of the polycrystalline silicon ingot.

Description

technical field [0001] The invention belongs to the field of polycrystalline silicon ingot production, and in particular relates to a non-sintering coating method for a crucible for polycrystalline silicon ingots. Background technique [0002] During the preparation of polycrystalline silicon ingots, the quartz crucible is an essential container. During the production of polycrystalline silicon ingots, the silicon material is melted, crystal grown, annealed and cooled in the crucible, and the single use of quartz crucibles will face the following hazards: [0003] ①Short service life and poor safety: When silicon melt and quartz crucible are in contact for a long time, viscosity will occur, and Si and SiO 2 The reaction produces SiO, which makes the crucible thinner or even cracked, resulting in major losses such as overflow of silicon liquid, reduced service life, and poor safety. [0004] ② Low utilization rate of silicon ingot: The crucible and silicon liquid are viscous...

AI Technical Summary

Problems solved by technology

[0003] ①Short service life and poor safety: When silicon melt and quartz crucible are in contact for a long time, viscosity will occur, and Si and SiO 2 The reaction produces SiO, which makes the crucible thinner or even cracked, resulting in major losses such as overflow of silicon liquid, reduced service life, and poor safety.

[0004] ② Low utilization rate of silicon ingot: The crucible and silicon liquid are viscous. During the cooling process of the silicon ingot, the crucible and the silicon ingot are broken due to the difference in thermal expansion coefficient between the two, resulting in poor utilization of the silicon ingot. At the same time, the available Silicon block may cause increased fragmentation rate of silicon wafer during slicing due to high residual stress

[0005] ③Contaminated silicon ingot: The raw material for ingot casting is high-purity silicon material with a Si content as high as 99.9999% (6N), and the purity of the high-purity quartz crucible is above 99.7%. Direct use of a quartz crucible will cause a large amount of impurities to enter the silicon ingot from the crucible Among them, such as C, O, Fe, B, P, etc., pollute the silicon ingot, reduce the yield, change the electrical and mechanical properties of the silicon ingot, and reduce the yield

However, due to poor bonding between silicon nitride and quartz crucible, the obtained Si 3 N 4 The coating is prone to large areas of powder loss and peeling