A review of ultra-short pulse laser micromachining of wide bandgap semiconductor materials: SiC and GaN

Wide bandgap (WBG) materials have excellent semiconductor and physicochemical properties and are emerging materials. Silicon carbide (SiC) and gallium nitride (GaN), two representatives of third-generation semiconductor materials, can be used in high temperature, high voltage, high frequency, and high power applications. However, both materials are difficult to machine due to their brittle and hard properties. Laser processing is a suitable processing method, and in particular the unique non-thermal properties of ultra-short pulse laser processing have led to a wide range of applications in a variety of materials including ceramics, metals and biological tissues. WBG materials are third-generation semiconductor materials with broad application prospects in the semiconductor industry, but there are relatively few summarized studies on ultrashort laser processing of WBG materials. With this background, this paper reviews the application of ultra-short pulse lasers for the processing of two WBG materials, SiC and GaN. Laser-assisted processing, laser fabrication of microstructures and laser processing of difficult and complex parts are the three main components of ultrashort laser processing of SiC. Ultra-short laser processing of GaN, on the other hand, focuses mainly on laser lift-off and is used less for fabricating microstructures. Physical mechanisms of laser removal of semiconductor materials are summarized. Then, based on the classification of the pulse width, the applications of two types of ultrafast lasers, picosecond and femtosecond, for processing SiC and GaN materials are summarized. Finally, the paper concludes and discusses the existing ultrafast laser processing techniques for SiC and GaN materials and future perspectives.