Recent progress toward a manufacturable polycrystalline SiC surface micromachining technology

In this paper, we present results of recent research from our laboratory directed toward a manufacturable SiC surface micromachining technology for microelectromechanical systems (MEMS) applications. These include the development of a low-pressure chemical vapor deposition and in situ doping processes for silicon carbide (SiC) films at relatively low temperatures, as well as the development of selective dry etching processes for SiC using nonmetallic masking materials. Doped polycrystalline SiC films are deposited at 800°C by using a precursor 1,3-disilabutane and dopant gas NH₃, with the minimum resistivity of 26 mΩ·cm. Dry etching for SiC and its selectivity toward silicon dioxide and silicon nitride masking materials are investigated using SF₆/O₂, HBr, and HBr/Cl₂ transformer coupled plasmas. The etch rate, etch selectivity, and etch profile are characterized and compared for each etch chemistry. By combining the LPCVD and dry etching process with conventional microfabrication technologies, a multiuser SiC MEMS process is developed.