New Designs for MEMS-Micromirrors and Micromirror Packaging with Electrostatic and Piezoelectric Drive

S. Gu-Stoppel, V. Stenchly, D. Kaden, H.J. Quenzer, B. Wagner, U. Hofmann, R. Dudde
Fraunhofer Institute Silicon Technology,
Germany

Keywords: micromirror, piezoelectric, actuator, wafer level packaging

Summary:

New devices of 1 and 2dimensional micro-mirrors based on new designs and new process capabilities using piezoelectric actuators are presented. For micro-mirrors an 8’’ wafer-level packaging process was developed using pre-processed borosilicate glass wafers. An optimized design of an optical package is presented that avoids any stray reflexes and ghost images in laser projection applications. For 1dimensional piezoelectric micro-mirrors, diameter 1.2 mm and 1 mm, scan angles in resonance mode of 40° and 73.2° at frequencies of 60 kHz and 27 kHz in ambient air have been achieved in various designs with driving voltages between 10 V and 15 V. For an integrated 2dimensional raster scanner with minimum dimensions a novel gimbal-mounted, piezoelectrically driven 2d micro-mirror was developed. The micro-mirror has two torsion modes with perpendicular axes, the respective resonant frequencies are 23.9 kHz and 1.5 kHz. For the x-axis a total optical scan angle of 22° was achieved, while the y-axis scan angle constitutes a value of 31° in resonant driving and 13.7° by quasi-statically driving.