Photoelectrochemical etching to fabricate single-crystal SiC MEMS for harsh environments

In this paper, we report on a novel surface micromachining process technology for the fabrication of microelectromechanical systems in SiC. Single-crystal SiC suspended microstructures were fabricated using a dopant-selective photoelectrochemical etching process, which allows for undercutting the p-SiC layer by rapid lateral etching of the underlying n-SiC substrate. The selective etching was achieved by applying a bias which employs the different flat-band potentials of n-SiC and p-SiC in the KOH solution. Single-crystal SiC MEMS developed in this study fully exploits the superior mechanical and biocompatible properties of SiC and has the capability of monolithic integration with electron devices and circuits, and therefore, is promising for sensing and actuating operations in biomedical, high-temperature and harsh environments.