采用环形感压薄膜的MEMS电容薄膜真空规设计

Design of MEMS diaphragm capacitive vacuum gauge with an annular sensing film

感压薄膜的结构改良能有效改善MEMS电容薄膜真空规的压力-电容输出特性。为解决MEMS电容薄膜真空规宽量程与高灵敏度相矛盾的问题,设计一种环形结构的感压薄膜,利用有限元的方法分析对比5种环形结构的感压薄膜在不同压力下的变形与应力分布情况。分析认为,同心圆结构的感压薄膜具有最优异的性能,同等感测面积情况下真空规的压力-电容线性输出测量上限能从圆片结构的1.1×103 Pa延伸到同心圆结构的1.2×104 Pa,圆片结构感压薄膜的真空规在1～800 Pa区间内的压力-电容输出非线性度为3.9%,灵敏度为10.1 fF·Pa–1;同心圆结构感压薄膜的真空规结构在1～8 000 Pa区间内的非线性度为3.6%,灵敏度为1.3 fF·Pa–1。

Structure optimizing can effectively enhance pressure-capacitance output performance of MEMS capacitive diaphragm gauge(CDG).In order to solve the conflict between wide measurement range and high sensitivity,a new type of MEMS(CDG)with an annular sensing film was proposed and five types of annular sensing films has been analyzed by using finite element method(FEM).The conclusion that the concentriccircles structure has better mechanism property has been delivered.According to the analyzing results,the measurement range can be stretched from 1.1×10^3 Pa of the circles-slice structure to 1.2×10^4 Pa of the concentric-circles structure under identical condition of sensing area.The circles-slice structure has the nonlinearity about 3.9%and sensitivity is 10.1 fF·Pa^–1 in 1-800 Pa and the concentric-circles structure has the nonlinearity of 3.6%and sensitivity is 1.3 fF·Pa^–1 in 1-8 000 Pa.