Y. Mizoguchi1 and M. Esashi21NEMS Platform Research Division, Leading-Edge Technology Development Headquarters, CANON Inc. TRANDUCERS’05The 13th International Conference on Solid-State Sensors, Actuators and Microsystems, Seoul, Korea, June 5-9, 2005, Vol. 1, pp 65-68

Design and Fabrication of a Pure -Rotation Microscanner with Self-Aligned ElectrostaticVertical Combdrives in Double SOI wafer

ReporterReporter ：： CHEN CHIH CHUNGCHEN CHIH CHUNG

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OutlineOutline

Motivation

Design and Fabrication

Experimental Results

Conclusion

Motivation

Vertical combdrive actuators commonly face the requirement of placing two sets of comb electrodes at different vertical positions, and require critical alignment of the comb electrodes

A tilt motion without unwanted vertical and lateral piston motions of a mirror is very important for a scanning device for high resolution

Increasing the rigidity of the torsional springs helps decreace the unwanted vertical and lateral piston motions, but increases the driving voltages

Design -Schematic view of the pure-rotation microscanner

Schematic cross-sectional view of the layout of the comb electrodes

Schematic cross-sectional view of the pure-rotation actuation.

a) clockwise rotation is achieved by applyingvoltages to electrodes E1,E2,E3,and E6.

b) anticlockwise rotation is achieved by applyingvoltages to electrodes E1,E2,E4,and E5.

Fabrication process

Thermal fusion bonding

etching out with TMAH solution

patterned by DRIE

self-aligned DRIE

Fabrication process

DRIE and BHF etching

SEM of the fabricated device

a) Top view of the device.

b) Close-up view of the torsional springs and the movable and fixed comb electrodes.

Shows the interferometric image of the surface of the fabricated device measured by WYKO

The measured characteristics of the devicein static scanning using the pure-rotation actuation

7.6 degrees at 150 Vdc

CONCLUSION

The pure-rotation microscanner has the following features

(a) The layout of the comb electrodes makes it possible to apply pure torque to the torsional springs.

(b) The fabrication process includes self-alignment and thickness control of the structure in the DRIE

(c) The static optical deflection angle was measured as 7.6 degrees at 150Vdc.

The improvement of the mirror flatness is our current interest