Investigation of Motion Behavior for the Opposite Connection Micro Optical Devices by CMOS-MEMS Process

摘要

The motion behaviors of the elevation for a pair of micro mirrors connected in opposite are investigated. The driving force of micro array thermal actuator, MATA, is applied for elevating the micro mirrors. The device design is followed Taiwan Semiconductor Manufacture Cooperation, TSMC, 0.35um 2P4M mixed signal model process design rule. The optimum number of springs and type of MATA are adopted based upon the simulation results. Simple double springs for connecting two mirrors and two pairs of {1×3} parallel type MATA for elevating the micro mirrors are the optimum design. The constricted motion in plane of two pairs of {1×3} parallel type MATA results in the out plane motion of two connected mirrors when the operation voltage is applied on MATA electrodes. The effects of the position of connection springs on the net displacement and the surface flatness of the elevated micro mirror surface varied with operation voltage are investigated. The results demonstrate the net displacement of elevated micro mirror is the largest, when the position of two springs for connecting two micro mirrors is at metal 3. On the other hand, the variation of surface flatness of the elevated micro mirror is relatively significant on the edges where are without any constricted. However, the variation of surface flatness is between 0.2μm and 0.4μm based upon a "C" shape structure layer at the back of mirror in thickness of metal 3. Nevertheless, the variation of surface flatness is below 0.1 μm when thickness of supporting structure layer is in thickness of metal 2 and metal 3 due to the high rigidity. When the operation voltage is 7V and the size of single micro mirror is 200μm × 200μm with a "C" shape supporting structure in thickness of metal 3 and metal 2 layers, the net displacement and inclined angle of the proposed micro optical device are 37.4 μm and 10.7°, respectively.