Stress characteristics of multilayer polysilicon for the fabrication of micro resonators

Micro polysilicon actuators, which are widely used in the field of MEMS (Microelectromechanical System) technology, were fabricated using polysilicon thin layers. Polysilicon deposition were carried out to have symmetrical layer structures with a LPCVD (Low Pressure Chemical Vapor Deposition) system, and we have measured physical characteristics by micro test patterns, such as bridges and cantilevers to verify minimal mechanical stress and stress gradient in the polysilicon layers according to the methods of mutilayer deposition, doping, and thermal treatment, also, analyzed the properties of each specimen, which have a different process condition, by XRD, and SIMS etc.. Finally, the fabricated planar polysilicon resonator, symmetrically stacked to thickness, showed Q of 1270 and oscillation ampitude of under DC 15V, AC 0.05V, and 1000 mtorr pressure. The developed micro polysilicon resonator can be utilized to micro gyroscope and accelerometer sensor.