A method for laying a seed crystal, a method for preparing a quasi-single crystal silicon wafer, and a quasi-single crystal silicon wafer

Abstract

The invention provides a method for laying a seed crystal, which is used for the casting of a quasi-single crystal, comprising the following steps: laying a seed crystal on the bottom of a crucible, and the crystal direction of the growth plane of the seed crystal is [001] or the same Seed crystals are in close contact with the bottom of the crucible to form a seed crystal layer, and the side crystal orientations of two adjacent seed crystals in contact belong to the same crystal orientation group and form a grain boundary of the coincident position lattice type: when the lateral crystal orientations of the seed crystals are When <110>, the crystal orientation of the adjacent seed crystal growth surface is [001], the front and back sides are alternately spliced, or one of the adjacent seed crystals is rotated 90°; when the crystal orientation of the side of the seed crystal is not <110> In the case of the crystal orientation group, the crystal orientations of the adjacent seed crystal growth surfaces are alternately spliced ​​according to the front and back sides, or one of the adjacent seed crystals is rotated 90° after the front and back sides are alternately spliced. The invention reduces the occurrence of dislocation sources in the crystal seeding process by laying seed crystals; the invention also provides a preparation method of a quasi-single crystal silicon chip and a quasi-single crystal silicon chip.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for laying a seed crystal, a method for preparing a quasi-single crystal silicon chip and a quasi-single crystal silicon chip. Background technique [0002] At present, the casting methods of quasi-single crystal mainly include seedless seeding and seeded seeding method. The seeded seeding method is to lay the single crystal seed crystal on the bottom of the quartz crucible first, and keep the seed crystal incompletely melted during the melting stage. , the seeding growth is carried out on the single crystal seed crystal to obtain the quasi-single crystal silicon ingot. When laying the seed crystal, the growth crystal direction of the nucleation surface of the seed crystal is generally guaranteed to be consistent, but the crystal orientation of the side contact surface of the adjacent seed crystal It is usually random, and it is easy to form small-angle grain b...

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Problems solved by technology

[0002] At present, the casting methods of quasi-single crystal mainly include seedless seeding and seeded seeding method. The seeded seeding method is to lay the single crystal seed crystal on the bottom of the quartz crucible first, and keep the seed crystal incompletely melted during the melting stage. , the seeding growth is carried out on the single crystal seed crystal to obtain the quasi-single crystal silicon ingot. When laying the seed crystal, the growth crystal direction of the nucleation surface of the seed crystal is generally guaranteed to be consistent, but the crystal orientation of the side contact surface of the adjacent seed crystal It is usually random, and it is easy to form small-angle grain boundaries during the seeding growth process. The small-angle grain boundaries not only become a dislocation source during the growth process, resulting in the continuous proliferation of dislocations during the growth process, but also metal impurities are easy to form at small angles. The enrichment and precipitation at the grain boundary induce secondary dislocation sources, reducing the crystal quality and single crystal yield of the quasi-single crystal; The crystal orientation is inconsistent, that is, the atomic packing density of the side normal direction of the seed crystal is inconsistent. During the seeding process, due to the anisotropy of the elastic modulus of the silicon crystal, the strain generated by the growth stress on the side normal direction on both sides of the splicing seam is also different. , it is easy to generate dislocation sources on the grain boundaries, and then continue to multiply during the growth process to generate a large number of dislocations, which will also reduce the crystal quality of the single crystal region

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