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Fabrication and Composition Control of NiTi Shape Memory Thin Films for Microactuators

Published online by Cambridge University Press:  01 February 2011

David J. Getchel
Affiliation:
Materials Engineering Department, California Polytechnic State University, San Luis Obispo, CA 93407, U.S.A.
Richard N. Savage
Affiliation:
Materials Engineering Department, California Polytechnic State University, San Luis Obispo, CA 93407, U.S.A.
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Abstract

Microactuators fabricated with NiTi thin films take advantage of the shape memory effect's large energy density (∼5-10 joules/cm3) and high strain recovery (∼8%). Microelectromechanical Systems (MEMS) designed with these actuators can serve as biosensors, micro-fluidic pumps or optical switches. However, the fundamental mechanical properties of these shape memory NiTi films have not been fully characterized with micro-scale test structures. Equiatomic NiTi thin films were deposited by co-sputtering NiTi and Ti targets with the intension of fabricating such test structures. Dual cathodes allowed direct control of the film composition by adjusting the Ti cathode power. Energy Dispersive Spectroscopy (EDS) quantified the film composition relative to pure standards. A thin (∼50 nm) chromium film on a pure silicon substrate created excellent film adhesion. Oxidized Si wafers did not bond with the Cr and NiTi films. This deposition method enabled control of film composition and the necessary adhesion.

Type
Research Article
Copyright
Copyright © Materials Research Society 2005

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