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Micromachining of mesoporous oxide films for microelectromechanical system structures

Published online by Cambridge University Press:  31 January 2011

Jong-Ah Paik
Affiliation:
Department of Materials Science and Engineering, University of California, Los Angeles, California 90095
Shih-Kang Fan
Affiliation:
Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095
Chang-Jin Kim
Affiliation:
Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095
Ming C. Wu
Affiliation:
Department of Electrical Engineering, University of California, Los Angeles, California 90095
Bruce Dunn*
Affiliation:
Department of Materials Science and Engineering, University of California, Los Angeles, California 90095
*
a)Address all correspondence to this author.
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Abstract

The high porosity and uniform pore size of mesoporous oxide films offer unique opportunities for microelectromechanical system (MEMS) devices that require low density and low thermal conductivity. This paper provides the first report in which mesoporous films were adapted for MEMS applications. Mesoporous SiO2 and Al2O3 films were prepared by spin coating using block copolymers as the structure-directing agents. The resulting films were over 50% porous with uniform pores of 8-nm average diameter and an extremely smooth surface. The photopatterning and etching characteristics of the mesoporous films were investigated and processing protocols were established which enabled the films to serve as the sacrificial layer or the structure layer in MEMS devices. The unique mesoporous morphology leads to novel behavior including extremely high etching rates and the ability to etch underlying layers. Surface micromachining methods were used to fabricate three basic MEMS structures, microbridges, cantilevers, and membranes, from the mesoporous oxides.

Type
Articles
Copyright
Copyright © Materials Research Society 2002

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