Identification of Structure Imbalance for Mems Tuning-Fork Resonators Based on Multi Transfer Functions Synthesis

This paper presents a novel measurement method for the structure imbalance parameters of a MEMS tuning-fork resonator at wafer level based on multi transfer functions synthesis. Compared with conventional simple modal test method that only obtains the resonant frequencies, quality factors and mechanical gain, this approach can identify more valuable parameters including individual stiffness of each sub-resonator, mismatch of stiffness, voltage to force coefficient and displacement to voltage coefficient, coupling stiffness, etc., which not only enhances the screening test capability for products from performances aspect but also reflects the fabrication errors in the wafer. We applied the test to four devices in the same wafer. The experimental results show a close agreement between the measured curves and the theoretical model as per the identified imbalance parameters. The chips considered as ‘good’ by the conventional method are successfully screened out with the proposed means.