1. Y. Mizoguchi1 and M. Esashi2 1NEMS Platform Research Division, Leading-Edge Technology Development Headquarters, CANON Inc. TRANDUCERS ’ 05 The 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 Electrostatic Vertical Combdrives in Double SOI wafer Reporter ： CHEN CHIH CHUNG

2. 2 Outline Motivation Design and Fabrication Experimental Results Conclusion

3. 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

4. Design -Schematic view of the pure-rotation microscanner

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

6. Schematic cross-sectional view of the pure-rotation actuation. a) clockwise rotation is achieved by applying voltages to electrodes E1,E2,E3,and E6. b) anticlockwise rotation is achieved by applying voltages to electrodes E1,E2,E4,and E5.

7. Fabrication process Thermal fusion bonding etching out with TMAH solution patterned by DRIE self-aligned DRIE

8. Fabrication process DRIE and BHF etching

9. 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.

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

11. The measured characteristics of the device in static scanning using the pure-rotation actuation 7.6 degrees at 150 Vdc

12. 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