Improved layout for a resonant 2D micro scanning mirror with low operation voltages
The Fraunhofer Institute of Microelectronic Circuits and Systems, Dresden, has been developing resonant Micro Scanning Mirrors for several years. They are designed for large deflection angles at low driving voltages in resonant operation. A couple of changes and optimizations in the layout of the 2-scanner that have improved performance and reliability are presented and discussed. Different variants have been fabricated by bulk-micromachining in bonded silicon-on-insulator-substrates and have been characterized. Mirror plate and gimbal can be rectangular or elliptical, now. New comb structures of the driving electrodes allow optimization of either capacitance, damping or electromechanical stability. Complex insulation structures reduce parasitic capacitance and increase reliability and mechanical stability. Various design variants were fabricated and characterized. Low-frequency devices with characteristic frequencies under 500 Hz reached scan ranges over 45° (..11.2 degrees mechanically) at voltages below 20V. The high-frequency devices with 8.4 kHz / 1 kHz reached 17.5° / 35° at 40 V / 30 V, respectively.