Hiroshi Noge

Vacuum Wafer Level Packaged Two-Dimensional Optical Scanner by Anodic Bonding

Vacuum wafer-level packaged two-dimensional optical scanners actuated by vertical electrostatic combs have been developed. A 1 mm-diameter gimbal mirror with high frequency deflection and a surrounding 2.5 × 3 mm movable frame with low frequency deflection are fabricated in a SOI wafer. Wafer-level packaging with anodically bonded borosilicate glass substrates on both sides together with non-evaporable getters fixed on the lower glass substrate allows hermetic sealing in high vacuum. The gimbal mirror and the movable frame are both deflected mechanically ± 12 deg. at a resonant frequency of 25.1 kHz with a driving voltage of 18 V, and at a resonant frequency of 78.6 Hz with a driving voltage of 10 V, respectively. The internal pressure of the device is 20 Pa.

Electrostatically Actuated Two-Dimensional Optical Scanner Having a High Resonant Frequency Ratio of Fast/Slow Axes

Two-dimensional resonant optical scanners actuated by vertical electrostatic combs with a unique electrical isolation structure have been developed. The isolation on the movable frame surrounding 1mm-diameter gimbal mirror is made by trenching the top silicon layer of an SOI wafer with leaving the thick bottom layers. Thanks to the large mass of the frame, the resonant frequencies range in 65.0-89.2Hz for the frame and in 11.9-36.8kHz for the mirror in a 4mm×4mm chip. The resultant frequency ratio of the fast/slow axes reaches over 500 and such a high frequency ratio is utilized to display QVGA image by raster scanning of a laser beam.