Effect of Electrode Geometry and Surface Passivation on Corrosion of Polycrystalline Silicon under High Relative Humidity and Bias

The combination of high electric fields and moisture from the environment can lead to electrochemical reactions causing corrosion, which can severely impact microelectromechanical systems (MEMS) device reliability and lifetime. In this paper, we present a detailed study of the corrosion behavior and surface passivation methods for enhancing the corrosion resistance of surface micromachined polycrystalline Si (poly-silicon) electrodes at high relative humidity and applied voltage. The results indicate the occurrence of anodic oxidation under positive bias and absence of cathodic protection under negative bias. Additionally, surface passivation chemistry, in particular employing self-assembled monolayers (SAM), is found to effectively enhance the corrosion resistance of the electrodes.