A preparation method of high-purity semi-insulating silicon carbide substrate

Abstract

The invention belongs to the technical field of novel material processing, and provides a completely novel method for preparing a high-purity semi-insulating silicon carbide substrate. The method comprises the following steps: performing rough processing on normally obtained silicon carbide single crystal, cutting so as to obtain crystal rods of 3-8mm in thickness, or processing so as to obtain silicon carbide wafers of 300-800[mu] m in thickness, and performing high-temperature rapid annealing on the crystal rods or the wafers, so as to obtain the high-purity semi-insulating silicon carbide substrate. By adopting the method, heat field adjustment in the silicon carbide crystal growth process can be avoided, and instead processed high-quality silicon carbide single crystal is directly subjected to secondary high-temperature rapid annealing processing, so that the semi-insulating property of the silicon carbide single crystal can be achieved by introducing intrinsic defects into crystal pieces, the obtained semi-insulating silicon carbide substrate is good in quality and simple in processing method, and the method is relatively high in efficiency when being compared with the prior art.

Description

technical field [0001] The invention belongs to the field of crystal processing of new materials, and in particular relates to a preparation method of a high-purity semi-insulating silicon carbide substrate. Background technique [0002] Silicon carbide (SiC) single crystal has the advantages of wide bandgap, high thermal conductivity, high critical breakdown field strength and high saturation electron drift rate, so it has become one of the core materials of the third generation semiconductor. Among them, the semi-insulating SiC single crystal substrate can effectively reduce the dielectric loss of the device and reduce the parasitic effect at high frequencies, so it is the preferred material for high-frequency and microwave devices. However, during the growth of silicon carbide single crystal by the usual physical vapor transport (PVT) method, due to the relatively high content of electroactive impurities (such as nitrogen, boron, aluminum, etc.) in the raw materials, insu...

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Problems solved by technology

Accordingly, CREE proposes to realize the semi-insulating properties of silicon carbide single crystal by controlling the thermal field of the silicon carbide single crystal growth interface to be in an unbalanced state, and performing rapid cooling after the crystal growth is completed to introduce intrinsic point defects into the crystal. However, there are still defects in this solution, which are reflected in: firstly, the thermal field adjustment of the solid / gas interface is technically difficult, and defects are prone to occur under non-equilibrium thermal field conditions, resulting in poor crystal quality and other problems; secondly , the annealing after the growth has limitations, because the cooling time in the single crystal growth chamber is long, the rate is slow, and the crystal thickness is large, it is difficult to uniformly introduce high-concentration intrinsic point defects inside the crystal, thus limiting the silicon carbide crystal. semi-insulating properties