Investigation of in situ trench etching process and Bosch process for fabricating high-aspect-ratio beams for microelectromechanical systems

Abstract

The in situ process and the Bosch process were compared for etching rates, etching profiles, and sidewall properties. As such, the Bosch process was found to be advantageous over the in situ process in achieving anisotropic etching profiles at high etching rates, due to selective deposition on the sidewall. The in situ process was advantageous over the Bosch process in forming small sized MEMS structures, since it avoided scallops and undercuts on the sidewall.