Sensitivity Analysis in Yield Optimization of MEMS Tunable Capacitors

The fabrication of MEMS tunable capacitors faces many uncertainties in which the fabricated dimensions differ from nominal values. This deviation in a tunable capacitor may cause significant variation in the capacitance-voltage response. In this paper, the effect of uncertainty in parallel-plate tunable capacitors is studied to maximize the yield under given criteria. A new method for yield optimization of tunable MEMS capacitors is developed. The method can take into account any arbitrary distribution and is not restricted to normality assumptions. The optimal designs verified by Monte-Carlo simulation exhibits considerable improvement in the yield. A sensitivity analysis is then performed to refine the design variables and maximize the yield based on the most effective parameters. When the fabrication process is already established and cannot be changed, the method can be employed to estimate the final yield for the process. The advantage of this method is demonstrated by numerical examples where the yield using initial design parameters is compared to the yield of the device with optimum parameters.