Sacrificial silicon carbide seed crystal protective film

Abstract

The invention provides a sacrificial silicon carbide seed crystal protective film which comprises a first silicon carbide polycrystalline film covering the front surface of the seed crystal and a second silicon carbide polycrystalline film covering the back surface of the seed crystal; nanoscale through holes are uniformly distributed in the first silicon carbide polycrystalline film; the second silicon carbide polycrystalline film is a double-layer composite film and sequentially comprises a first film layer and a second film layer; the back surface of the seed crystal is sequentially covered with the second silicon carbide polycrystalline film, a carbon film and graphite paper, and the second film layer is attached to the carbon film. As the defect density of the silicon carbide polycrystalline film is greater than that of the seed crystal, the silicon carbide polycrystalline film is volatilized preferentially in the heating process, and the generated gas is filled near the surface of the seed crystal, so that the volatilization speed of the surface of the seed crystal is delayed, and the seed crystal is protected. The carbon film is used for reducing the exposed area of the second film layer and delaying volatilization of the second film layer. The graphite paper has an isolation effect on the silicon carbide and the seed crystal tray, the stress of the seed crystal is reduced, and the seed crystal and the crystal are prevented from cracking.

Description

technical field [0001] The invention relates to a sacrificial silicon carbide seed crystal protective film, which belongs to the technical field of protective films. Background technique [0002] As the third-generation wide-bandgap semiconductor material, silicon carbide crystal has excellent properties such as high breakdown critical field strength, high electron saturation drift rate and high thermal conductivity, and can be widely used in the production of high-frequency, high-power, high-temperature-resistant power devices and in radio frequency devices. [0003] The industrial growth of silicon carbide crystals mainly adopts the physical vapor transport method (PVT method), that is, the silicon carbide raw material is heated and sublimated above 2100°C and decomposed to produce carbon source gas and silicon source gas, and the gas generated by the decomposition is transported to the seed crystal. Recrystallize to obtain a larger area of ​​silicon carbide (SiC) single ...

AI Technical Summary

Problems solved by technology

In most cases, the seed crystal will be burnt through before crystal growth, resulting in voids, which will extend until the end of crystal growth, resulting in defects such as micropipes and polycrystals in the crystal, and even the entire crystal is scrapped

[0005] At present, no measures have been found in the industry to protect the front of the seed crystal; the usual treatment for the back of the seed crystal is to bond graphite paper or carbon film to the back of the seed crystal, but it is difficult to eliminate the gap between the back of the seed crystal and the graphite paper. During the crystal growth process, the tiny air bubbles between them will still extend out of voids or micropipes, resulting in a decline in the quality of the crystal, and even the entire crystal cannot be used.

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