Process Stress Estimation for MEMS RF Switches with Capacitive Test Structures

One of the basic parameters in RF capacitive switches is the actuation voltage. It strongly depends on the process stress accumulated in the switching structure, typically a suspended thin bridge, made of conductive materials. The control and the tuning of the deposition steps require the monitoring and the reduction of the process stress. We present a method to estimate the global process stress of the device taking advantage of the electrical characterization done on standard capacitive test structures integrated in the process layout.