Polycrystalline silicon ingot, preparation method of polycrystalline silicon ingot, polycrystalline silicon slice and crucible for polycrystalline silicon ingot casting

Abstract

The invention provides a preparation method of a polycrystalline silicon ingot. The preparation method comprises the following steps that a core source is arranged at the bottom of a crucible, and a core source layer is formed; silicon materials in a molten state are arranged on the core source layer; and the temperature in the crucible is controlled to gradually rise in a direction vertical to the upward direction form the bottom of the crucible, the temperature gradient is formed, the silicon materials in the molten state form core crystallization by utilizing the core source, and the polycrystalline silicon ingot is prepared. The invention also provides high-quality polycrystalline silicon ingot obtained by the preparation method, a polycrystalline silicon slice obtained through the preparation of the polycrystalline silicon ingot and the crucible for polycrystalline silicon ingot casting. The polycrystalline silicon ingot prepared by the preparation method has the advantages that the crystalline size is uniform and regular, the dislocation density is low, and in addition, no obvious pine-tree crystals or twin crystals exist.

Description

technical field [0001] The invention relates to the field of polycrystalline silicon ingots, in particular to polycrystalline silicon ingots and a preparation method thereof, polycrystalline silicon slices and a crucible for polycrystalline silicon ingots. Background technique [0002] At present, the preparation method of polycrystalline silicon ingot mainly adopts the directional solidification system method (DSS for short) furnace crystal growth technology provided by GT Solar, which usually includes the steps of heating, melting, solidification growth, annealing and cooling. During the process of solidification and crystal growth, with the continuous cooling of the bottom of the crucible, the silicon material in molten state spontaneously forms random nucleation and the random nucleation gradually grows. However, since the initial nucleation is not controlled, dislocations are prone to occur during the nucleation process, resulting in irregular crystal orientation, irreg...

AI Technical Summary

Problems solved by technology

Although the polycrystalline silicon ingot produced by this method has few initial dislocations and slow proliferation, it has the following disadvantages: (1) The crystal grains grow rapidly in the form of dendrites, and different dendrites are easy to squeeze each other, resulting in stress and defects; (2) The grown grains are relatively large, and once there are dislocations inside the large grains, it is easy to expand inside the entire large grains and occupy the entire grain; (3) The growth of dendrites exothermic, relatively The heat released by large grains during the growth process is likely to affect the supercooling required for the growth of other grains around them, making it difficult for other grains to grow, so this method is not suitable for large-scale industrial

Images