Effects of Relative Humidity and Actuation Voltage on MEMS Reliability

Polycrystalline silicon (polysilicon) microelectromechanical systems (MEMS) commonly operate under high electric fields. When combined with humidity from the environment, corrosion becomes a critical reliability issue. Oxidation at the anode is frequently observed and reported. In this paper, we provide the first report of damage occurring at the cathode in polysilicon MEMS under high relative humidity. This unusual phenomenon is determined to be electrochemical and chemical in nature. The accelerating factors leading to cathodic dissolution are discussed and suggestions to prevent such damage are presented.