Paving method of seed crystals, pseudo-single crystal silicon wafer and preparation method of pseudo-single crystal silicon wafer

Abstract

The invention provides a paving method of seed crystals for casting a pseudo-single crystal silicon wafer. The paving method comprises the following steps: providing a crucible; paving target seed crystals at the bottom of the crucible; reserving a gap between two adjacent target seed crystals and filling the gap with an anisotropic seed crystal, wherein the target seed crystals and the anisotropic seed crystals are tightly contacted and fill the bottom of the crucible to obtain a seed crystal layer; the anisotropic seed crystal comprises a first side face and a second side face which are respectively contacted with the side faces of the two adjacent target seed crystals, the types of crystal boundaries respectively formed by the first and second side faces and the side faces contacted with the adjacent target seed crystals are consistent, and the growth faces of the anisotropic seed crystals is high index crystal faces relative to the growth faces of the target seed crystals. By filling the anisotropic seed crystals in the gaps between two adjacent target seed crystals, dislocation and proliferation of dislocation preferably occur in the anisotropic seed crystals, so that the probability of generating dislocation of the target seed crystals is reduced, and the problem that the pseudo-single crystal prepared in the prior art is more in dislocation is solved.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for laying a seed crystal, a quasi-single crystal silicon wafer and a preparation method thereof. Background technique [0002] At present, the casting methods of quasi-single crystal mainly include seedless crystal seeding and seed crystal seeding method. The seed crystal 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...

AI Technical Summary

Problems solved by technology

[0002] At present, the casting methods of quasi-single crystal mainly include seedless crystal seeding and seed crystal seeding method. The seed crystal 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, and the strain generated by the growth stress on the side normal direction on both sides of the splicing seam is different, which can easily cause dislocation sources on the grain boundary, and then in the growth The continuous propagation in the process produces a large number of dislocations, which will also reduce the crystal quality of the single crystal region

Images