Reliability studies of single crystal silicon beams for rigid micro mirrors

The micro mirror supported by torsional beams is fabricated by the SCREAM process. The frame and the supporting beams consist of a single crystal silicon (SCS) core, coated by SiO/sub 2/ and Al. The mirror is twisted or moved out of plane by applying bias between the mirror and the substrate. In order to understand the reliability of the mirror-beam system, we study the failure mechanism of a single crystal silicon bar subjected to torsion and bending. The result implies that the failure strength of SCS increases by about two orders of magnitude as the size is reduced to the /spl mu/m scale-the scale used to support micro mirrors. It thus follows that the beams can sustain very large deformations before failure.