圆片级封装全硅梳齿电容式MEMS加速度计设计

A design of capacitance MEMS accelerometer with wafer level encapsulated all-silicon comb tooth

针对小型化惯性测量单元对加速度计的集成需求,设计制作了一款全硅梳齿电容式MEMS加速度计。该加速度计采用"日"字型结构方案,检测和施力反馈电容由变间隙的梳齿组成,可动结构采用深硅反应离子干法刻蚀实现,芯片采用硅-硅键合圆片级常压封装,芯片内部电信号通过深反应离子刻蚀和湿法腐蚀加工的硅通孔引出。该加速度计芯片最终和模拟ASIC电路采用陶瓷管壳封装,整表尺寸12.7×12.7×3.25 mm^3。小批量测试结果显示该加速度计标度因数约80 m V/g,0 g输出稳定性优于100mg(1σ),零偏稳定性和重复性优于100mg(1σ),-40°C^+70°C零偏漂移小于20 mg。

An all-silicon comb tooth capacitive MEMS accelerometer is designed and manufactured to meet the integrated requirements of miniaturized inertial measurement unit(IMUS).The accelerometer adopts a"日"type structure scheme.The measuring and applying force feedback capacitance is composed of comb teeth with variable clearance.Moving structures of the accelerometer are fabricated by deep reactive ion etching,and then encapsulated by silicon-silicon fusion bonding at wafer level under atmospheric pressure.Internal signals of the accelerometer are led out through TSVs that fabricated by deep reactive ion etching and wet etching.The accelerometer chip is finally encapsulated in a ceramic tube shell of 12.7×12.7×3.25 mm^3 with an analog ASIC circuit.Test results show that the scale factor of the accelerometer is about 80 m V/g,the output stability at 0 g is better than 100μg(1σ),the zero-deviation stability and repeatability are better than 100μg(1σ),and the zero-deviation drift of-40℃^+70℃is less than 20 mg.