Measuring Effective Flexure Width by Measuring Comb Drive Capacitance

We measure the effective flexure width of a pair of microelectromechanical systems (MEMSs) by measuring their change in comb drive capacitance upon deflection from applied voltage. This effective width is the value that a corresponding model must have in order to match the performance of the true device. Due to process variations, small changes in width from layout have been shown to increase stiffness by as much as 100%. Existing measurement methods can be costly, have unknown accuracy, are not amenable to industrial-scale batch testing, depend on the measurements of additional quantities, and so on. Our electrical probing method appears to address many of these issues. Our method requires an actuating voltage and capacitance sensing of a pair of MEMS that only differ in layout flexure width. We test our method using a low-cost capacitance meter and compare our results against a high-cost scanning electron microscope technique. We achieve nanometer scale uncertainty.