A thermal field structure for growing silicon carbide single crystal

Abstract

The present invention discloses a thermal field structure for growing a silicon carbide single crystal, and belongs to the field of preparation of a silicon carbide single crystal. According to the present invention, the thermal field distribution of a PVT method is improved, a conventional method of creating an axial temperature gradient through heat dissipation of upper thermal insulation holesis changed into a method of using different thicknesses of crucibles and different thicknesses of thermal insulation structures to create an axial temperature gradient and at the same time changing the thermal insulation structure on the upper side of the crucibles, so that a thermal field structure with uniform radial temperature distribution is produced, and in particular, the radial distribution of the internal thermal field of a large-size crucible is uniform. Since electroactive impurity elements grow into the crystal with the temperature gradient, the thermal field structure with uniformradial temperature distribution guides the electroactive impurity elements to be evenly distributed in the radial direction, thereby preparing a large-sized high-purity semi-insulating silicon carbide single crystal and single crystal substrate with uniform radial resistivity and low stress.

Description

technical field [0001] The application relates to a thermal field structure for growing a silicon carbide single crystal, which belongs to the field of silicon carbide single crystal preparation. 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 center of the coil through intermediate frequency ...

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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

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