Analysis of Thermally Actuated Micromirrors

Abstract

Use of microelectromechanical system (MEMS) to craft deformable mirror is in the embryonic stage. However, MEMS micromirrors hold significant advantages in speed, compactness, and economy in comparison to macroscale counterparts. The MEMS micromirrors are fabricated by silicon batch processing or micrometer scale lithographic pattering technique which offer flexibility in low volume manufacturing and inter batch variations. The project is a structural study and involves the modeling of various geometries for MEMS micromirrors and simulations results that were carried out using COMSOL Multiphysics. An important parameter involved in the working of micromirror during lift off is the surface deformation and the bridge supporting the mirror is designed to provide maximum deformation i.e., to maintain flat surface at top during lift off so that distortion can be minimized. The results of all the three differently shaped bridge structure of micromirrors are analyzed in terms of induced stress along the edges of the micromirror due to lift off, surface deformation during lift off and maximum displacement of the micromirror.