薄膜残余应力对MEMS微型光栅性能的影响

微型光栅结构薄膜中由于残余应力的存在引起器件在光学和机械性能方面发生显著变化．有限元仿真和分析结果表明，膜内的残余拉应力越大，越利于提高和改善器件工作过程中的光学效率．然而，残余拉应力的增加将显著增大结构工作时的驱动电压，使驱动电路的设计与制作更加复杂；同时，还将导致结构的最大工作位移明显减小，极大限制了光栅的应用领域．另外，残余拉应力的增加也会使结构的共振频率变大，从而影响器件的工作带宽．因此，为了使光栅的使用和工作性能满足设计指标要求，在设计当中就要充分并折中考虑残余应力对各个性能参数的影响．并且在随后的加工和制作过程中对其进行严格控制．

Effects of Residual Stresses in Thin Films on Performances of MEMS-Based Microgratings

Effects of residual stresses on the optical and mechanical performances of MEMS-based microgratings were investigated using finite element simulation method. The results show that larger the tensile residual stress, more advantageous to improve the working optical efficiency of microgratings. However, as the tensile residual stress increases, driving voltage required for operating the grating structures is greatly enhanced, which makes the design and making of driving circuitry more complicated. Meanwhile, maximum working dis- placement of the grating structures will be decreased notably with the tensile residual stress increasing, restrict- ing the application fields. In addition, structural resonant frequency will also be increased, affecting the work- ing bandwidth of the gratings. As a result, to meet the demand of design, sufficient considerations for the effects of residual stresses on the performances of micrograting structures should be taken and strict control of the residual stresses during process should be performed.