环形氮化铝压电MEMS谐振器的支撑结构设计研究

Support structure design research of circular AlN piezoelectric MEMS resonator

基于有限元仿真研究了方环和圆环形谐振器的静态位移点,并分析了支撑轴位置对谐振器性能的影响,提出了优化设计方案:对于方环形谐振器,在对角处设置双端侧向支撑以降低其锚点损耗;对于圆环形谐振器,采用单端侧向支撑以及三端底部支撑相结合的器件结构,在保证电学信号引出的同时,提升器件的品质因数Q。针对所设计的器件结构特征,设计了一种基于七步光刻工艺的微纳制程,并成功实现器件的高成品率制备。测试结果表明:前者的Q值和机电耦合系数k_(eff)^(2)分别为1707.4和0.98%,后者的Q值和k_(eff)^(2)分别为1844.7和1.58%。相比于四端支撑环形谐振器,优化设计的支撑结构使得器件Q值得到大幅提升。此外,还分析研究了不同表面电极材料对环形谐振器的性能影响。

The static displacement points of the square-ring and circular-ring resonators are researched by finite element simulation,influence of support shaft position on performance of resonators is analyzed and optimal designing scheme are proposed.For the square-ring resonator,two-end lateral support are set at the opposite corners of the square ring to reduce anchor loss;for the circular-ring resonator,a combination of a single-end lateral support and three-end bottom supports is proposed to improve its quality factor Q while ensuring the extraction of electrical signals.Aiming at the structural characteristic of designed devices,a micro-/nano-fabrication process based on seven-step photolithography is designed,and the high-yield fabrication of the devices is successfully achieved.The measured results show that the Q value and electro-mechanical coupling coefficient k_(eff)^(2)of the former are 1707.4 and 0.98%,and the later are 1844.7 and 1.58%,respectively.Compared to the ring resonators with four-end support,the Q values of the device with optimized support structures is significantly promoted.In addition,the influence of different surface electrode materials on device performance is also analyzed.