A polysilicon ingot casting process

Abstract

The invention discloses a polycrystalline silicon ingot casting technology. The technology comprises the following steps of 1 auxiliary heater installing, wherein an auxiliary heater is installed in a polycrystalline silicon ingot casting furnace and is a bottom heater arranged under a crucible; 2 charging; 3 preheating; 4 melting, wherein the process comprises the following steps of six-side heating melting, five-side heating melting and follow-up melting; 5 crystal growing pretreating after melting, wherein the process comprises the steps of temperature decreasing and temperature increasing; 6 crystal growing; 7 annealing and cooling, wherein after the crystal growing process in the step 6 is completed, annealing and cooling are conducted, and processed and formed polycrystalline silicon ingots are obtained. The technology is simple in step, reasonable in design, easy and convenient to achieve and good in using effect, heating is conducted by adopting a six-side heating device, and by adding the step of conducting crystal growing pretreating after melting and regulating a crystal growing process, the grain size can be effectively decreased, and the quality of the finished ingots is improved.

Description

technical field [0001] The invention belongs to the technical field of polysilicon ingot casting, and in particular relates to a polysilicon ingot casting process. 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. In recent years, the production technology of polycrystalline silicon wafers has made remarkable progress, and the polycrystalline ingot casting technology has progressed fro...

AI Technical Summary

Problems solved by technology

At present, in the process of polysilicon ingot casting, there is no unified, standard and standardized method for reducing the grain size (that is, the method of processing fine-grained polysilicon ingot casting method) to follow. In actual processing, it is inevitable that the operation is relatively random and expensive. Long time, poor use effect and other problems

[0004] In addition, the heaters used in the existing polysilicon ingot furnaces generally have a five-sided heating structure, that is, heaters are installed on the top of the crucible and outside the four side walls. This five-sided heating method heats up from top to bottom. Radiation, melting efficiency is low, and at the same time, the gas at the bottom of the crucible is difficult to get rid of, so that the oxygen content at the bottom of the finished ingot is relatively high

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