膜片上薄膜体声波谐振器型微加速度计

发布时间：2018-07-25 16:23

【摘要】：针对"FBAR(薄膜体声波谐振器)-梁"结构悬臂梁厚度不足、"嵌入式FBAR"结构微加工工艺复杂的缺点,提出了新型"膜片上FBAR(FBAR-on-diaphragm)"结构的微加速度计。其弹性膜片由氧化硅/氮化硅复合薄膜构成,既便于实现与硅微检测质量和FBAR的IC兼容集成加工,也利于改善微加速度计的灵敏度和温度稳定性。对由氧化硅/氮化硅双层复合膜片-硅检测质量惯性力敏结构和氮化铝FBAR检测元件集成的膜片上FBAR型微加速度计进行了初步的性能分析,验证了该结构的可行性。通过有限元模态分析和静力学仿真得出惯性加速度作用下膜片上FBAR结构的固有频率和弹性膜片上的应力分布;选取计算所得的最大应力作为FBAR中压电薄膜的应力载荷,结合依据第一性原理计算得到的纤锌矿氮化铝的弹性系数-应力关系,粗略估计了惯性加速度作用下氮化铝薄膜弹性系数的最大变化量;采用射频仿真软件,通过改变惯性加速度作用下弹性常数所对应的纵波声速,对比空载和不同惯性加速度作用下加速度计的谐振频率,得到加速度计的频率偏移特性和灵敏度。进一步分析仿真结果还发现:氧化硅/氮化硅膜片的一阶固有频率与高阶频率相隔较远,交叉耦合小;惯性加速度作用下,谐振频率向高频偏移,灵敏度约为数k Hz/g,其加速度-谐振频率偏移特性曲线具有良好的线性。
[Abstract]:Aiming at the shortcomings of the FBAR (thin film bulk acoustic resonator)-beam structure cantilever beam thickness and the complex micromachining technology of "embedded FBAR" structure, a new type of micro-accelerometer with "FBAR (FBAR-on-diaphragm)" structure on the diaphragm is proposed. The elastic film is composed of silicon oxide / silicon nitride composite film, which is easy to integrate with silicon micro-detection quality and IC compatibility of FBAR, and can also improve the sensitivity and temperature stability of micro-accelerometer. The performance analysis of the FBAR type microaccelerometer integrated with silicon oxide / silicon nitride bilayer composite film and aluminum nitride FBAR detector was carried out, and the feasibility of the structure was verified. Through finite element modal analysis and static simulation, the natural frequency and stress distribution of FBAR structure on the diaphragm under inertial acceleration are obtained, and the calculated maximum stress is selected as the stress load of piezoelectric film in FBAR. Based on the relationship between elastic coefficient and stress of wurtzite aluminum nitride, the maximum variation of elastic coefficient of aluminum nitride film under inertial acceleration is estimated roughly by means of RF simulation software. By changing the longitudinal wave velocity corresponding to the elastic constant under the action of inertial acceleration, the resonant frequencies of accelerometers under the action of no load and different inertial accelerations are compared, and the frequency offset characteristics and sensitivity of accelerometers are obtained. The simulation results also show that the first order natural frequency of the silicon oxide / silicon nitride film is far away from the high order frequency and the cross-coupling is small, and the resonant frequency shifts to the high frequency under the action of inertial acceleration. The sensitivity is about the number k Hz / g, and the characteristic curve of acceleration-resonant frequency offset has good linearity.
【作者单位】：中国工程物理研究院电子工程研究所;西南科技大学信息工程学院;重庆大学新型微纳器件与系统技术国防重点学科实验室;重庆大学光电技术及系统教育部重点实验室;
【基金】：中国工程物理研究院超精密加工技术重点实验室基金(2014ZA001,2012CJMZZ00009) 重庆大学新型微纳器件与系统技术国防重点学科实验室访问学者基金(2013MS04) 西南科技大学特殊环境机器人技术四川省重点实验室开放基金(14zxtk01) 中物院电子工程研究所科技创新基金(S20141203) 西南科技大学研究生创新基金(13YCJJ36,14YCX107,14YCX109,14YCX111)
【分类号】：TH824.4

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