Stress characteristics of multilayered polysilicon film for the fabrication of microresonators

Micro-polysilicon actuators, which are widely used in the field of microelectromechanical system (MEMS) technology,were fabricated using a novel stacking method. Polysilicon film was deposited to have a symmetrical layer structure using a low-pressure chemical vapor deposition (LPCVD) system. We have also measured the physical characteristics using micromachined test patterns to verify the minimal stress and stress gradient in the polysilicon layers, according to the film stacking, doping, and thermal treatment methods. Finally, the fabricated planar polysilicon resonators, symmetrically stacked to 6.5 mu m thickness, showed Q of 1270 and oscillation amplitude of 5 mu m under 1000 m Torr. The developed micro-polysilicon resonator can be utilized in the fabrication of both microgyroscopes and accelerometer sensors.