IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Microelectromechanical Systems (MEMS) Thursday Sessions
       Session MM-ThA

Paper MM-ThA7
Analog Beam Steering Vertical Comb Drive MEMS Actuator

Thursday, November 1, 2001, 4:00 pm, Room 130

Session: Fabrication and Integration Processes for MEMS
Presenter: J.J. Fijol, Standard MEMS, Inc.
Authors: J.J. Fijol, Standard MEMS, Inc.
J. Prohaska, Standard MEMS, Inc.
M. Smith, Standard MEMS, Inc.
T. Wester, ProcessTek
G.W. Tasker, Standard MEMS, Inc.
Correspondent: Click to Email
The design, modeling, fabrication and characterization of a vertical comb drive actuator are presented. This micro-electro-mechanical device includes a rotating platform supported by two torsion springs and an integrated vertical comb drive actuator. The comb structure was etched into the underside of the rotating platform yielding a compact three-dimensional device. An Au mirror was deposited on the rotating platform and the actuator was used for single axis analog beam steering. The vertical comb design eliminates pull-in, generates large actuation forces (>500 µN) and minimizes the footprint to dimensions approximately equivalent to the size of the mirror (1750 x 2000 µm). Device fabrication required fusion bonding of two wafers; a thick (1000 µm) Si bottom wafer and a top SOI wafer. Deep reactive ion etching (DRIE) was used to etch one half of the comb structure into the substrate wafer and the other half into the handle of the SOI wafer. The mirror platform and torsion hinges were formed in the SOI wafer’s device layer using a novel dry release process that eliminated stiction. A matrix of devices were fabricated with varying comb lengths, number of comb fingers and gap spacing (between the upper and lower comb fingers). Devices were operated with a single sided displacement and rotational angles of ~13 degrees were measured for an applied voltage of 200V. Resonant frequency measurements were also performed and the primary resonances were observed between 30 to 200 Hz. Characterization of the mirror surfaces using interferometric microscopy shows the mirror flatness to be better than @lambda@/30 (at @lambda@ = 1550 nm), yielding diffraction limited beam steering.