叉指式硅微加速度计的结构设计

Design a multi finger silicon micromechanical accelerometer

为了满足对中等精度的微机械加速度计的需求，讨论了一种硅片溶解法制造的平面叉指式加速度计，其敏感轴平行于检测质量平面。为了分析该种加速度计的分辨率和固有频率，分析了其机械模型和数值解，并且用有限元方法对几种设计尺寸进行了仿真。着重研究了几个关键尺寸，如检测质量厚度和梁的宽度的改变对分辨率和固有频率的影响，并且给出了此种结构在当前条件下的所能得到的测量分辨率极限。最后，给出了两种尺寸的设计，其大小约为１．５ｍｍ×１．５ｍｍ，检测质量厚１０μｍ和１５μｍ，相对于当地重力加速度，分辨率分别为５×１０－３和３×１０－３。

In order to fulfill the need for a moderate accurate accelerometer, a multi finger parallel accelerometer based on silicon on insulator (SOI) process has been designed. Its sensitive direction is parallel to the proof mass. A mechanical model and mathematical solution are presented, which have been developed in order to calculate the sensitivity and frequency behavior. The finite element analysis (FEA) method is also be used. This paper emphases on the discussion of the changes of the sensitivity, frequency, the acceleration measurements range, caused by the changes of the main dimensions such as the thick of the proof mass, the width of the beam of the acceleration sensor. In the end, two designs are described. The size of the sensor is about 1.5mm×1.5mm, the proof masses are 10μm and 15μm thick and the sensitivities relative to gravitational acceleration are 5×10 -3 and 3×10 -3 , respectively