Orientation-Dependent Acceleration Sensitivity of Silicon-Based MEMS Resonators

In this paper, the effect of crystalline orientation on acceleration sensitivity of silicon-based microelectromechanical resonators is investigated for the first time. In addition, the correlation between the nonlinearity of the resonators and the corresponding acceleration sensitivity is experimentally demonstrated. For this purpose, thin-film piezoelectric-on-substrate (TPOS) resonators are fabricated aligned to three different crystalline orientations: <100>, <110>, and 5 degree off <110> on the same highly-doped n-type silicon wafer. Based on our measurement results, both the amplitude-frequency nonlinear behavior and acceleration sensitivity of the resonators decrease as the resonators are rotated from <100> toward <110>. The average acceleration sensitivity measured for the resonator aligned to the <110> plane is similar to 4x10(-10) which is two orders of magnitude lower than the recorded sensitivity for the device aligned to the <100> plane (similar to 4.4x10(-8)).