残余应力是微机械表面加工过程中不可避免的,残余应力的存在会影响微机械器件的性能。通过引入等效力学模型,推导出残余应力作用下静电驱动微镜的吸合电压和行程的表达式,定量地研究了残余应力对吸合电压和行程的影响。同时还研究了残余应力对微镜本征频率的影响,发现本征频率随着残余拉应力的增加而增大。采用白光干涉仪对不同残余应力情况下的微镜表面形貌进行了实验测试,结果表明,残余应力会引起表面翘曲,从而使微镜的斯特列尔比下降,成像质量变差。

Residual stress is an inevitable factor in microelectromechanical system (MEMS) surface micromachining,it affects the performances of the devices. In this paper,the formulas for calculating the pull-in voltage and the stroke of an electrostatic micromirror with residual stress existed have been derived by introducing an equivalent mechanical model,and the effect of the residual stress on the eigen-frequency of the micromirror is analyzed. The result shows that the eigen-frequency increases with the residual stress. The micromirror surface profile,under different residual stress,is tested by a white light interferometer. Experimental results indicate that the residual stress makes a warp on the surface,and it declines Strehl ratio and lower the image quality.