A polysilicon ingot casting process

Abstract

The invention discloses a polycrystalline silicon ingot casting process. The process comprises the following steps: 1, preheating; 2, melting; 3, growing crystal: the temperature is controlled to T6 and is preserved for 1h, and T6=1420 DEG C; the hoisting height of a heat insulation cage is 90mm; the temperature is controlled to T6 and is preserved for 2h, and the hoisting height of the heat insulation cage is not changed; the temperature is controlled to T6 and is preserved for 3h, and the hoisting height of the heat insulation cage is 110mm; the temperature is gradually lowered from T6 to T7, the temperature lowering time is 7-9h, and the hoisting height of the heat insulation cage is 210mm; T7=1405 DEG C; the temperature is controlled to T7 and is preserved for 7-9h, and the hoisting height of the heat insulation cage is not changed; the temperature is controlled to T7 and is preserved for 7-9h, and the hoisting height of the heat insulation cage is not changed; the temperature is gradually lowered from T7 to T8, and the hoisting height of the heat insulation cage is not changed; T8=1395 DEG C; 4, annealing and cooling. The polycrystalline silicon ingot casting process has the advantages of simple steps, reasonable design, convenience in realization, easiness in grasp and good using effect and can reasonably control the ingot casting crystal growth process.

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 for the production of 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 pro...

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, most manufacturers cannot accurately control the crystal growth process, resulting in defects such as sticky pots, crystal cracks, hard spots, and microcrystals.

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