Large-rotation and low-voltage driving of micromirror realized by tense thin-film torsion bar

An electrostatically driven micromirror device using a thin-film torsion bar is proposed. The mirror rotation angle of 7.3deg at 5 V is demonstrated at the nonresonant condition. A bulk Si micromirror is suspended by SiN thin-film torsion bars. Inside the torsion bar, the tension having the magnitude larger than that of the driving force is included. The torsion bar can have a compliance with the mirror rotation and the rigidity against the unwanted motions (e.g., vertical displacement or in-plane rotation)