Design and test of dual axis silicon resonant angular rate sensor using electromagnetic excitation and electromagnetic/capacitive detection

In this paper, a micro electro mechanical systems (MEMS) angular rate sensor is designed, fabricated and tested. Silicon bars are used for supporting and vibrating structures. Electromagnetic force is used to create reciprocating movement in the driving mode. The designed frequency of driving mode is 5 955.38 Hz. For the angular rate detection of another two axises, the designed detection mode frequencies are 6151.01 Hz and 6591 Hz, respectively. The maximum displacement of the mass in driving mode is 20 μm. Wet etching, electron beam (EB) evaporation, anodic bonding, plasma enhanced chemical vapor deposition (PECVD), lift-off and inductive coupled plasma reactive ion etching (ICP-RIE) are used for device fabrication. The size of the mass is 1440 μm×1400 μm×33.6 μm. And the parameters of the silicon bars are 10 μm×562.5 μm×33.6 μm and 10 μm×532.5 μm×33.6 μm, respectively. The size of chip is 3127 μm×3069 μm. For device testing, the vacuuming test equipment is set up. The test result shows that the resonant frequency for driving mode is 9609 Hz, and that for electromagnetic detection mode is 9605 Hz. The capacitive detection needs the special circuit, and the experiment is carried on. The reason for the resonant frequency difference between device testing and simulation is the error between design and fabrication process.