提高微压传感器灵敏度的深盆腔压力膜片研究( 一)

表面微机械微小量程压力传感器采用多晶硅薄膜等有内应力的敏感膜片时,应力往往会
使膜片的力学灵敏度大大下降,无法满足微量程测量的要求。波纹膜片可以消除或减小应力来提高灵敏度,但是其波纹结构本身又会造成力学灵敏度下降,从而部分抵消了应力消除的效果。提出一种新型深盆腔膜片结构,在消除应力的同时实现了比平膜片还高的力学灵敏度,可以提高微压传感器和微麦克风的灵敏度。采用解析和有限元两种方法相结合的方法,对该种膜片进行了分析和研究。对比平膜和波纹膜结构,显示了深盆腔膜在力学灵敏度方面的显著提高。
关键词:压力膜片;微机械传感器;力学灵敏度;薄膜残余应力
Abstract :When thin - film with residual stress used for sensitive diaphragm of micromachined low - range pressure sensors ,mechanical sensitivity of the diapgragm is ,more often than not ,much lowered due to the stress. Currently ,corru2 gated diaphragm is used for stress release ,thereby ,improving the mechanical sensitivity. However ,corrugated diaphragm
itself is with a stiffened structure compared with conventional flat diaphragm that renders a lower mechanical sensitivity. Therefore ,There is a trade off when a corrugated diaphragm employed for pre - stressed diaphragm. A novel deep cavity - shaped diaphragm is proposed in this paper. The structure is capable of simultaneously releasing the stress and decreasing
mechanical stiffness. Analysis and finite element method (FEM) are combined to study the mechanical principles of the di2 aphragm. The results show that the proposed deep cavity - shaped structure is with much improved mechanical sensitivity , compared with conventional flat diaphragm and corrugated diaphragm.
Key Words :Pressure - sensitive Diaphragm;Micromachined Sensors ;Mechanical Sensitivity ;Residual Stress of Thin - film