Fabrication of polysilicon surface micromachined MEMS structures

Polysilicon structures such as cantilevers with electrostatic actuators, mirrors, comb drives, and heaters were fabricated using a surface micromachined process. The fabrication process included 8 photo levels, two LPCVD nitride layers and four polysilicon layers. Details such as the incorporation of etch stops, deposition at higher than normal temperatures to reduce deposition times and anisotropic etch chemistry are important for the successful fabrication of these structures. Measurements were made throughout the fabrication process and pictures were taken at several points in the process. The completed wafers were tested and actuator structures were videotaped.