Large-sized high-purity silicon carbide single crystal, single crystal substrate and preparation methods thereof

Abstract

The invention discloses a large-sized high-purity silicon carbide single crystal, a single crystal substrate and preparation methods thereof, and belongs to the field of silicon carbide single crystals and single crystal substrates. The preparation method of the large-sized high-purity silicon carbide single crystal comprises the following steps: after a seed crystal unit is installed at a crucible filled with a silicon carbide powder, placing the crucible in a cavity of a closed thermal-insulation structure, transferring the whole system into a crystal growth device; and then conducting impurity removal and crystal growth, so as to prepare a high-purity semi-insulating silicon carbide single crystal. A semi-insulating silicon carbide single crystal substrate is obtained by conducting cutting, grinding and polishing on the high-purity semi-insulating silicon carbide single crystal. In the preparation methods of the large-sized high-purity silicon carbide single crystal and single crystal substrate, an axial temperature gradient is created by using different thicknesses of crucibles and different thicknesses of thermal insulation structures, and a thermal insulation structure at theupper side of a crucibles is changed, so that a thermal field with uniform radial temperature distribution is created, and thus a large-sized silicon carbide single crystal and single crystal substrate of 4 to 12 cun can be obtained, and the prepared large-sized high-purity silicon carbide single crystal and single crystal substrate have uniform electric resistivity and small inner stress.

Description

technical field [0001] The application relates to a large-scale high-purity silicon carbide single crystal, a single crystal substrate and a preparation method thereof, belonging to the field of silicon carbide single crystal and its substrate. Background technique [0002] Since the commercialization of semiconductor silicon carbide single crystal materials in the 1990s, after nearly 30 years of development, it has gradually become the preferred substrate material for power electronic devices and microwave radio frequency devices. With the continuous development of downstream device technology and the continuous improvement of industrialization, the quality requirements of silicon carbide single crystal substrates are becoming increasingly stringent. [0003] At present, the most mature silicon carbide single crystal preparation technology is the physical vapor transport method (referred to as PVT method). The basic principle is to heat the graphite crucible placed in the c...

AI Technical Summary

Problems solved by technology

[0004] However, as the crystal size continues to increase, so does the diameter of the crucible

Since the crucible wall is used as the heat source in the medium frequency induction heating method, the radial temperature gradient along the crucible wall and the center of the crucible is also increasing; in addition, the PVT method uses the thermal insulation center hole on the upper side of the crucible as the heat dissipation center to create an axial temperature gradient. , which will further cause the radial inhomogeneity of the thermal field inside the crucible, resulting in large thermal stress and uneven distribution of impurities and defects in the crystal along the radial direction.

The thermal stress in the former is likely to lead to serious quality problems such as cracks in the crystal processing process, unqualified curvature and warpage in the substrate processing process, and the uneven distribution of impurities and defects in the latter will also seriously restrict the substrate along the diameter. Uniformity of electrical resistivity and other issues

Images