Crystalline silicon and preparation method thereof

Abstract

The invention discloses a preparation method of crystalline silicon, which comprises the following steps: a mono-crystal silicon seed crystal is randomly paved in the center of the bottom of a crucible to form a seed crystal layer; a nucleation source is paved at the residual part of the bottom to form a nucleation source layer; a silicon material in a melting state is arranged on the seed crystal layer and the nucleation source layer to control the temperature of the bottom of the crucible so as to prevent the seed crystal layer and the nucleation source layer from being completely molten; and the temperature in the crucible is controlled to gradually increase to form temperature gradient in the direction vertical to the upward direction of the bottom of the crucible, so that the molten silicone material can form nuclear crystallization on the mono-crystal silicone seed crystal and the nucleation source and the crystalline silicon of which the center is mono-like and the periphery is high-effective polycrystal. The invention further discloses the crystalline silicon prepared by the preparation method for crystalline silicon. The preparation method for crystalline silicon reduces the consumption of the mono-crystal silicone seed crystal, saves the production cost, improves the quality of the silicon block in the area close to the side wall of the crucible; and monocrystal-like silicon and high-effective polycrystal silicone coexist in the prepared crystalline silicone, and the complementary advantages of the monocrystal-like silicone and the high-effective polycrystal silicone are realized.

Description

Technical field [0001] The invention relates to the field of semiconductor preparation, in particular to a crystalline silicon containing both single-crystal and high-efficiency polycrystals and a preparation method thereof. Background technique [0002] Crystalline silicon is the most commonly used semiconductor material in the manufacture of solar cells. At present, crystalline silicon used to manufacture solar cells is mainly monocrystalline silicon using the Czochralski method and polycrystalline silicon using ingot casting technology. Polycrystalline silicon ingots have the advantages of large feeding volume, simple operation and low process cost, but the battery conversion efficiency is low and the life is short; the Czochralski monocrystalline silicon conversion efficiency is high, but the single feeding is small, the operation is complicated, and the cost is high. How to combine the two into one and form complementary advantages has become a hot and difficult point in the...

AI Technical Summary

Problems solved by technology

[0004] However, there is no mature process for the production of quasi-monocrystalline silicon wafers at present. In the prior art, the bottom of the crucible is generally covered with monocrystalline silicon seed crystals (such as figure 1 ), and then filled with silicon material, heated and melted and the temperature at the bottom of the crucible is controlled to prevent the seed crystal from being completely melted, so that the silicon liquid grows on the seed crystal that has not been completely melted, and grows a quasi-single crystal with a single crystal structure

This process not only requires a large amount of seed crystals and high production costs, but also due to the uniformity and orientation of the thermal field, it is difficult to grow single crystals in the area close to the side wall of the crucible, and most areas are polycrystalline areas (such as figure 2 ), severely affects the ratio of single-crystal

Since this area is the coexistence area of ​​single crystal and polycrystalline, the crystal grains are squeezed against each other, and dislocations are easy to expand and proliferate, resulting in poor quality of silicon blocks in this area, and low cell conversion efficiency, even lower than that of ordinary polycrystalline silicon wafers.

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