Direct bonding SOI Wafer based MEMS cantilever resonator for trace gas sensor applicaiton

A thermal driving and piezoresistive sensing MEMS cantilever resonator has been proposed and developed to construct trace gas detection sensors. The problem of integrating vibration structure, transducers and electric elements is the main concern in the design and fabrication of the resonator. In this paper, the parameters and the configuration of the resonator are discussed, the fabrication process and the test results are presented. Finite Element Analysis (FEA) has been carried out to optimize the configuration of the resonator to obtain high sensitivity and efficiency with a uniform temperature distribution that is propitious to the function of the gas sensing material. The fabrication process is based on direct bonding silicon-on-insulator (SOI) wafer and inductive coupled plasma (ICP) etching technology, which conciliate the semiconductor processes and the micromachining processes, and provide precise control of the resonator parameters. The experimental test results of the fabricated resonator agreed well with the calculation and simulation results and demonstrated that the proposed resonator was qualified to construct trace gas detection sensors.