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Title: Electrostatic comb drive for vertical actuation

The electrostatic comb finger drive has become an integral design for microsensor and microactuator applications. This paper reports on utilizing the levitation effect of comb fingers to design vertical-to-the-substrate actuation for interferometric applications. For typical polysilicon comb drives with 2 {micro}m gaps between the stationary and moving fingers, as well as between the microstructures and the substrate, the equilibrium position is nominally 1-2 {micro}m above the stationary comb fingers. This distance is ideal for many phase shifting interferometric applications. Theoretical calculations of the vertical actuation characteristics are compared with the experimental results, and a general design guideline is derived from these results. The suspension flexure stiffnesses, gravity forces, squeeze film damping, and comb finger thicknesses are parameters investigated which affect the displacement curve of the vertical microactuator. By designing a parallel plate capacitor between the suspended mass and the substrate, in situ position sensing can be used to control the vertical movement, providing a total feedback-controlled system. Fundamentals of various capacitive position sensing techniques are discussed. Experimental verification is carried out by a Zygo distance measurement interferometer.
Authors:
Publication Date:
OSTI Identifier:
16389
Report Number(s):
UCRL-JC-127771; CONF-970968*--
ON: DE98051008; TRN: US200302%%627
DOE Contract Number:
W-7405-Eng-48
Resource Type:
Conference
Resource Relation:
Conference: The International Society for Optical Engineers Micromachining and Microfabrication Conference, Austin, TX (US), 09/29/1997--09/30/1997; Other Information: Supercedes report DE98051008; PBD: 10 Jul 97; PBD: 10 Jul 1997
Sponsoring Org:
(US)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; CAPACITORS; DAMPING; DESIGN; ELECTROSTATICS; ENGINEERS; FINGERS; LEVITATION; PLATES; RECOMMENDATIONS; VERIFICATION