Design and fabrication of micromirror array supported by vertical springs

A 50/spl times/50 /spl mu/m/sup 2/ aluminum micromirror array is fabricated using surface micromachining technology. 50 by 50 micromirrors are arrayed two dimensionally. A micromirror plate is supported by a vertical spring structure which is placed underneath the mirror plate. With this structure, when the mirror plates reflect light, the micromirror array can have a large effective reflecting area. Only one mask and one shadow evaporation process is used in the fabrication of vertical springs. Measurement of the electromechanical characteristics of the fabricated micromirror revealed that the downward threshold voltage was 8 V, the step response time was 20 /spl mu/s when a 29 V step voltage was applied, and the resonant frequency was 11 kHz.