A surface micromachined silicon gyroscope using a thick polysilicon layer

A new silicon gyroscope is presented in this paper. It has a measuring range of /spl plusmn/100/spl deg//s and a resolution of 1.26/spl deg//s at 10 Hz bandwidth. The mechanical sensor structure consists of polysilicon and its lateral extension is 1600 /spl mu/m. The gyro element is 11 /spl mu/m thick and less than 19 /spl mu/g in weight. This structure is suspended in its centre of gravity with a thin tether beam. The tether beam is shaped in a way that the sensor structure can be tilted around its three axes. The gyroscope is fabricated using silicon surface micromachining technology incorporating several new process steps. These new steps are mainly thick polysilicon deposited in an epitaxy reactor, the deep silicon etching and a new stiction free release etch. The gyro structure is electrostatically driven in an in-plane torsional dithering motion. In response to an external angular rate the drive motion is coupled into an out-of-plane motion which is measured capacitively.