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We know that further epitaxial layers need to be built on top of some wafer substrates for device fabrication, typically LED light-emitting devices, which require GaAs epitaxial layers on top of silicon substrates; SiC epitaxial layers are grown on top of conductive SiC substrates for building devices such as SBDs, MOSFETs, etc. for high voltage, high current and other power applications; GaN epitaxial layers are built on top of semi-insulating SiC substrates for building HEMTs and other RF applications.

There are two types of epitaxy: homogeneous and heterogeneous. In order to produce SiC devices with specific resistance and other parameters for different applications, the substrate must meet the conditions of epitaxy before production can begin. The quality of the epitaxy affects the device's performance.

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.

At first glance, quartz (SiO2) material looks very similar to glass, but what is special is that ordinary glass is composed of many components (such as quartz sand, borax, boric acid, barite, barium carbonate, limestone, feldspar, soda ash, etc.), while quartz only contains SiO2, and its microstructure is a simple network composed of silicon dioxide tetrahedral structural units.

Oxidation processes play a critical role in preventing such problems by creating a protective layer on the wafer, known as the oxide layer, which acts as a barrier between different chemicals.

As technology nodes continue to shrink, the formation of ultra-shallow junctions presents significant challenges. Thermal annealing processes including Rapid thermal annealing (RTA) and flash lamp annealing (FLA) are vital techniques that maintain high impurity activation rates while minimizing diffusion, ensuring optimal device performance.