Method for rapidly growing large-size high-purity semi-insulating silicon carbide single crystal

Abstract

The invention relates to a method for rapidly growing a large-size high-purity semi-insulating silicon carbide single crystal. According to the method, on one hand, through multiple times of gas replacements conducted on a growing chamber, the insulation of the growing chamber and air is achieved, the nitrogen content in the single crystal is reduced, on the other hand, the rapid-growth of the silicon carbide single crystal is achieved through improving temperature gradient between source powder and a seed crystal in a silicon carbide single crystal growing system of a PVT method and / or reducing pressure of the growing chamber, and the crystal forms of the high-purity semi-insulating silicon carbide single crystal comprise a 4H, 6H, 3C and 15R or an arbitrary combined crystal form of the four crystal forms. The method for rapidly growing the large-size high-purity semi-insulating silicon carbide single crystal has the advantages that resistivity of the silicon carbide single crystal is improved, the growth speed of the silicon carbide single crystal can reach 0.5 mm / h-2 mm / h, the growth speed exceeds the conventional speed for multiple times, and the productive rate of the silicon carbide single crystal is further improved.

Description

technical field [0001] The invention relates to a method for growing a silicon carbide single crystal, in particular to a method for rapidly preparing a large-sized high-purity semi-insulating silicon carbide single crystal. Background technique [0002] Silicon carbide (SiC) material is the third-generation semiconductor material after silicon (Si) and gallium arsenide (GaAs), with wide band gap, high critical breakdown field strength, high electron saturation drift rate, high thermal conductivity, etc. It has become an ideal material for making high-temperature, high-frequency, high-power, and radiation-resistant devices. [0003] Semi-insulating silicon carbide single crystals include vanadium-doped semi-insulating and high-purity semi-insulating. When using a vanadium-doped silicon carbide substrate to make a device, vanadium can trap charges and cause an endogenous gate effect, which affects device performance. Therefore, it is best to use a high-purity semi-insulat...

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Problems solved by technology

[0004]The difficulty in growing high-purity semi-insulating silicon carbide single crystal is to reduce the impurities in the crystal, but due to the inevitable existence of Al, B At the same time, a large amount of N in the air will be incorporated into the crystal during the growth process, which greatly affects the electrical properties of silicon carbide single crystal.

The content of Al and B can be effectively reduced by using high-purity source powder, high-purity graphite crucible and high-purity insulation materials, but it is difficult to reduce the N entering the growth chamber through the atmosphere, which has become the main factor restricting the realization of high-purity semi-insulating performance of silicon carbide single crystal factor

[0005]At present, the domestic high-purity semi-insulating silicon carbide single crystal growth rate is slow and the production efficiency is low, which cannot meet the requirements of device manufacturers for single crystals with a size of 3~4 inches and resistance The demand for large-scale silicon carbide substrates with a rate greater than 106 Ω·cm and a nitrogen content lower than 9×1016 atom / cm3

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