Test method for capacitive MEMS devices utilizing pierce oscillator

In this paper a test method for MEMS devices is presented in which physical defects are detected in the frequency domain rather than the time domain. A resonator, that can be part of a read out circuit, is utilized to test capacitive Micro-Electro-Mechanical Systems (MEMS). The proposed technique is based on the principle of resonant frequency where variations of the resonant frequency are observed to detect structural defects. To verify the validity of the proposed approach, a MEMS comb-drive is designed and fabricated. Measurement and simulation results indicate that the proposed method can be used to capture common comb-drive defects such as missing or broken fingers, shorted fingers and tilted arms.