Polycrystalline silicon ingot and preparation method thereof, and polycrystalline silicon chip

Abstract

The invention discloses a preparation method of a polycrystalline silicon ingot. The method comprises the following steps: (1) filling a silicon material into a crucible, heating and melting the silicon material to form a silicon liquid, adjusting a thermal field to achieve an overcold state, carrying out nucleation crystallization with the silicon liquid on the crucible, wherein the crystal nucleation process is a first crystallization stage; (2) after crystal with a target height grows out, putting a nucleation material on the surface of the crystal with the target height, namely a solid-liquid interface of an un-crystalized silicon liquid and the crystal with the target height, and stopping the first crystallization stage, or putting the nucleation material at the position at the target height in advance, obtaining the crystal with the target height after the crystal grows to the target height, and stopping the first crystallization stage, maintaining the overcold state in the step (1), wherein the un-crystalized silicon liquid is subjected to nucleation recrystallization by virtue of the nucleation material; and the nucleation recrystallization process is a subsequent crystallization stage; and (3) after the silicon liquid is completely crystallized, annealing and cooling, so as to obtain the polycrystalline silicon ingot. The preparation method disclosed by the invention is simple; and the prepared polycrystalline silicon ingot is low in dislocation rate.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a polycrystalline silicon ingot, a preparation method thereof and a polycrystalline silicon chip. Background technique [0002] At present, the DSS (Directional Solidification System) method is widely used in polysilicon casting. The process generally includes steps such as heating, melting, crystallization, annealing, and cooling. The crystal grains of polysilicon ingots grown from quartz crucibles are mostly from the bottom to The head is columnar, and the bottom of the silicon ingot is mainly nucleated in the form of dendrites, and the orientation of the formed dendrites is random, and there are a large number of grains with harmful crystal orientations, dislocations and other defects. The dislocation density at the bottom of the polysilicon ingot manufactured by the normal ingot casting process can be from (1.5~8.2)×10 4 / cm 2 Increase to (1.8~78)×10 of the head ...

AI Technical Summary

Problems solved by technology

Although this method can reduce dislocations, it is difficult to operate, and the control of the degree of supercooling may not be able to produce secondary nucleation. The nucleation power is low and the risk is high, and there are still many dislocations in the final polysilicon ingot.

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