Integrated surface-micromachined z-axis frame microgyroscope

Abstract

We report the first integrated surface-micro machined z-axis frame microgyroscope fabricated in the Analog Devices Modular-MEMS process using 6 /spl mu/m thick polysilicon as the structural material and 5 V 0.8 /spl mu/m CMOS process. This vibratory microgyroscope, which operates in vacuum, measures the z-axis rotation rate by sensing the induced Coriolis acceleration using capacitive sensing. The amplitude of drive motion was estimated to be 2 /spl mu/m. The frame gyroscope mechanically decouples the drive and sense motion for stable operation. Integration of circuits and mechanical structures on the same substrate allowed signal sensing with low parasitics. The surface micromachined integrated z-axis frame gyroscope fabricated at Analog Devices has a measured noise floor of 0.05 deg/s//spl radic/Hz and a scale factor of 0.33 mV/deg/sec at 70 mtorr ambient pressure.