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SiC substrate can have microscopic defects, such as Threading Screw Dislocation (TSD), Threading Edge Dislocation (TED), Base Plane Dislocation (BPD), and others. These defects are caused by deviations in the arrangement of atoms at the atomic level. SiC crystals may also have macroscopic dislocations, like Si or C inclusions, micropipe, hexagonal voids, polymorphs, etc. These dislocations are typically large in size.

Tantalum carbide coating is an important high-strength, corrosion-resistant and chemically stable high-temperature structural material with a melting point of up to 4273 °C, one of the several compounds with the highest temperature resistance. It has excellent high-temperature mechanical properties, resistance to high-speed airflow scouring, ablation resistance, and good chemical and mechanical compatibility with graphite and carbon/carbon composites. Therefore, in the epitaxial process of GaN LEDs and SiC power devices such as MOCVD, TaC coating has excellent acid and alkali resistance to H2, HCl, NH3, which can completely protect the graphite substrate material and purify the growth environment.

As a wide-bandgap (WBG) semiconductor material, SiC's wider energy difference gives it higher thermal and electronic properties compared to traditional Si. This feature enables power devices to operate at higher temperatures, frequencies and voltages.

Currently, many semiconductor devices employ mesa device structures, which are predominantly created through two types of etching: wet etching and dry etching. While the simple and rapid wet etching plays a significant role in semiconductor device fabrication, it has inherent drawbacks such as isotropic etching and poor uniformity, which result in limited control when transferring small-sized patterns. Dry etching, however, with its high anisotropy, good uniformity, and repeatability, has become prominent in semiconductor device fabrication processes. The term “dry etching” broadly refers to any non-wet etching technology used for removing surface materials and transferring micro and nano patterns, including laser etching, plasma etching, and chemical vapor etching. The dry etching discussed in this text specifically pertains to the narrow application of processes using plasma discharge—either physical or chemical—to modify material surfaces.

Both epitaxial and diffused wafers are essential materials in semiconductor manufacturing, but they differ significantly in their fabrication processes and target applications. This article delves into the key distinctions between these wafer types.