薄膜体声波谐振器微加速度计惯性力敏特性

Inertial force sensing characteristics of Film Bulk Acoustic wave Resonators micro-accelerometer

摘要:

研究了由硅微质量块-悬臂梁惯性力敏结构和氮化铝(AlN)薄膜体声波谐振器(FBAR)检测元件集成的FBAR微加速度计表头的惯性力敏特性。采用有限元(FEA)静力学仿真，得到惯性力载荷作用下硅微悬臂梁上的应力分布；选取最大应力值作为载荷，基于第一性原理计算纤锌矿AlN的弹性系数与应力的关系式，预测惯性力载荷作用下AlN弹性系数的最大变化量；采用谐响应分析，预测FBAR微加速度计的加速度-谐振频率偏移特性。分析得到：惯性力载荷作用下，FBAR微加速度计的谐振频率向高频偏移，灵敏度约为数kHz/g；其加速度增量-谐振频率偏移特性曲线具有良好的线性度。

Abstract:

The inertia force sensing characteristics of FBAR(Film Bulk Acoustic wave Resonators) micro- accelerometer sensor are studied, which integrates inertial force sensing structure of silicon micro mass-proof and cantilever beams with AlN(Aluminum Nitride) FBAR detecting elements. The stress distribution of silicon micro supporting beam under the inertia force loads are obtained by applying Finite-Element Analysis(FEA) static simulation. Then the maximum stress value is selected as load, the relationships between elastic coefficient and stress of wurtzite AlN are calculated according to the first principles. Therefore, the maximum variation of AlN elastic coefficient under the inertia force load can be predicted. Next, the micro-accelerometer frequency characteristics and the tendency of FBAR micro-accelerometer are predicated through the analysis of harmonic response. It is concluded that the resonance frequency of FBAR micro-accelerometer shifts to a higher one under an inertial load, with a sensitivity about kHz/g; and there exists a good linearity in the acceleration increment-frequency shift characteristic curve.