Batch-fabricated scanning micromirrors using localized plastic deformation of silicon

We have demonstrated batch-processed scanning micromirrors using self-aligned and localized plastic deformation of silicon such that the whole process is compatible with on-chip microelectronics. The micromirrors are made of single-crystal silicon and actuated by self-aligned vertical comb-sets at a resonant frequency of 4.13 kHz with optical scanning angles up to 50.9 degrees under driving voltages of 30 V_dc plus 14 V_PP. After continuous operation of 6 billion cycles at the maximum scanning angle, there appears to be no observable degradation or fatigue of the plastically deformed silicon torsion bars. Novel designs for torsional springs to prevent the buckling problem due to the non-uniform thermal expansion by localized heating are also presented.