静电刚度式谐振微加速度计的结构设计和制造

Structure design and fabrication for resonant accelerometer based on electrostatic stiffness

基于静电刚度的谐振式微加速度计能通过加载电压来调节灵敏度,减少了灵敏度对结构工艺误差的依赖性。根据单梁谐振加速度计的动力学原理,确定了输出频率与各活动结构位移的非线性关系。对于输出频率与加速度的复杂非线性求解问题,提出在谐振梁刚度远大于折叠梁刚度条件下,可以有效的得到二者的解析关系式,为结构设计提供了约束条件。对于差分结构,推导了面内低阶模态方程,提出应减少音叉梁连接端的刚度系数来减少工艺误差造成的模态扰动误差。采用ICP干法体硅工艺,在很少的工艺步骤下能实现高深宽比结构的流片。实验测试发现结构完整可动,但存在同频干扰问题,提出了高频调制开关解调的信号处理办法。理论分析和实验测试为设计新型谐振式微加速度计提供了依据。

The introduced resonant accelerometer makes use of the equivalent electrostatic stiffness to sense the acceleration.The sensitivity can be adjusted by changing the applied sensing voltage and it is robust for the fabrication error.According to the sensing principle,the dynamic model of the single beam accelerometer is built along with the no-linear relationship of the output frequency and the displacement of all positive components.When the stiffness of the vibrating beam is much bigger than the stiffness of the fold beam,the sensitivity can effective achieve.It is the restriction for the structure design.For the differential structure,mode analysis shows it is a lower mode in plane for the work mode.Decreasing the stiffness of connected end for the double vibrating beam can reduce the disturbance error.The bulk micromachining for the resonant accelerometer can achieve high depth width ration etching.The experiment find the structure is not broken and there is the same frequency disturbance problem.FM is suggested to deal with the disturbance.Theory analysis and test provides some important conclusions for the design of the novel type resonant accelerometer.