An investigation of stiction in poly-SiGe micromirror

Permanent or temporary stiction remains one of the most critical reliability concerns for micro-electro-mechanical systems (MEMS). In this paper, we present an investigation of stiction of standard poly-SiGe MEMS. This is done by analyzing the hysteresis in the displacement-versus-voltage characteristics of electrostatically actuated micromirrors. The width of the “pull-in window” is used as an indication of the amount of mirror-to-surface stiction. Differences in the pull-out voltage of micromirrors within an array indicate varying levels of stiction from mirror to mirror. A FDTS self-assembled monolayer (SAM) is applied to reduce this in-use stiction. Analytical and finite element methods are used to quantify the magnitude of stiction.