Microfabricated torsional actuator using self-aligned plastic deformation

We describe microfabricated torsional actuators that are made using self-aligned plastic deformation in a batch process. The microactuators are formed in single-crystal silicon and driven by vertical comb-drives. Structures have been built that resonate at frequencies between 1.90 and 5.33 kHz achieving scanning angles up to 19.2 degrees with driving voltages of 40 V/sub dc/ plus 13 V/sub ac/. After continuous testing of 5 billion cycles at the maximum scanning angle, there appears to be no observable degradation or fatigue of the plastically deformed silicon tors ion bars. We present measured results obtained with MEMS scanning mirrors; the actuators may be useful for many other MEMS applications.