MEMS“三明治”倾角传感器的仿真分析和优化设计

Simulated analysis and optimization design of MEMS Sandwich inclinometer

摘要:

对MEMS“三明治”式倾角传感器进行结构优化设计，敏感元件采用双梁-质量块结构，其中可动质量块通过双梁和周围框架相连，可动质量块和上下盖板构成上下差分电容。外界给定某一加速度时，上下间隙此消彼长，从而导致电容量发生变化。通过建立敏感元件的静力学模型，获得敏感元件的关键尺寸与其性能参数的关系，基于体硅工艺建立敏感元件的三维工艺模型，并采用ANSYS有限元仿真对敏感元件的灵敏度、线性度、谐振频率等参数进行分析计算，结果表明：敏感结构的一阶谐振频率为576.68 Hz，灵敏度为0.76 pF/g，±30°、±90°对应的线性度分别为0.8‰、3‰，均符合设计要求，最后给出了倾角传感器敏感元件的加工流程。

Abstract:

In this paper, the structure optimization design of MEMS "sandwich" inclinometer is mainly carried out. The sensing element adopts double beam-mass block structure, in which the movable mass block is connected with the surrounding frame through the double beam. The movable mass block, the top and the bottom plate constitute differential capacitance. When the external acceleration is loaded, the gap between the movable mass block and top-bottom plate will change which results in the changes of differential capacitance. The relationship between key performances and structure parameters is obtained by building up three-dimensional micromachining model of the sensing element based on bulk-micromachining process. The results from ANSYS FEA show that the sensitivity and the first-order resonant frequency are 0.76 pF/g and 576.68 Hz respectively with the linearity 0.8‰ and 3‰ for ±30° and ±90° measurement range, all of which meet the design requirements. In the end, the fabrication process of sensing element is also presented.