High-temperature crystal growth technology for polysilicon semi-molten ingot

Abstract

The invention discloses a high-temperature crystal growth technology for a polysilicon semi-molten ingot. The technology is characterized in that an ingot furnace is heated from room temperature to 1550-1555 DEG C, the thickness of bottom seed crystals is measured in the later stage of melting, the power ratio of a top heater and a lateral heater is adjusted, it is guaranteed that bottom seed crystals are not molten through slow melting, after melting is finished, the power ratio of the top heater and the lateral heater is adjusted, when the temperature is cooled to 1440-1445 DEG C, directional solidification starts, the crystal growth process starts, the temperature is reduced from 1440-1445 DEG C to 1400-1405 DEG C in the crystal growth process, and the crystal growth process is finished. The method is simple in step, reasonable in design, convenient to implement, easy to control and good in use effect, the polysilicon ingot crystal growth process can be reasonably controlled, and polysilicon ingot quality is effectively improved.

Description

【Technical field】 [0001] The invention belongs to the technical field of polycrystalline silicon ingot casting, and in particular relates to a high-temperature crystal growth process for polycrystalline silicon semi-molten ingot casting. 【Background technique】 [0002] Photovoltaic power generation is one of the most important clean energy sources with great development potential. The key factors restricting the development of photovoltaic industry are low photoelectric conversion efficiency on the one hand and high cost on the other hand. Photovoltaic silicon wafers are the basic material for the production of solar cells and components. The purity of polysilicon used to produce photovoltaic silicon wafers must be above 6N (that is, the total content of non-silicon impurities is below 1ppm), otherwise the performance of photovoltaic cells will be greatly negative influences. [0003] In recent years, the production technology of polycrystalline silicon wafers has made rem...

AI Technical Summary

Problems solved by technology

When actually casting polysilicon ingots, the control of the crystal growth process directly affects the quality and yield of the finished ingot. If the crystal growth is stable, a higher minority carrier lifetime and better yield can be obtained; if the crystal growth process is not well controlled, May cause defects such as sticky pot, crystal cracks, hard spots, microcrystals, etc., directly affecting the yield

Nowadays, when casting polysilicon ingots, the existing crystal growth process is a gradual cooling process, which belongs to the cooling process of the whole ingot. During the process, the molten state at the top is kept for a short time, and the impurities discharged during the partial condensation process at the bottom cannot be discharged in time. Solidification forms hard spots, and manufacturers cannot accurately control the crystal growth process, resulting in defects such as sticky crucibles, crystal cracks, hard spots, and microcrystals

Images