Microelectromechanical Systems Advanced Materials and Fabrication Methods (1997) / Chapter Skim
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3 New Materials and Processes
3 New Materials and Processes
Pages 23-33
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From page 23... ...
The principal techniques for applying force in IC-based MEMS rely on electrostatic or thermalexpansion prime movers, which produce relatively small forces and limited interaction lengths. Materials other than those available in the typical silicon IC complement will have to be integrated into MEMS to make use of physical prime movers that are potentially capable of delivering higher forces or greater interaction lengths.
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From page 24... ...
This basic process has also been combined with nickel plating to produce highly conducting regions on the HEXSIL plates for contacts and conducting patterns. Thermal expansion of resistively heated HEXSIL regions has been used to actuate HEXSIL structures, such as the tweezers.
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From page 25... ...
compliant surface polysilicon tips built on HEXSIL foundation; (f) transition from micro- to milk-scale beams provides mechanical interface; (g)
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From page 26... ...
In Germany, the use of replication techniques has been heavily pursued. One reason for the two approaches is the availability of high-energy x-ray source laboratories in the United States (e.g., the National Synchrotron Light Source, the Stanford Synchrotron Radiation Laboratory, and the Advanced Photon Source)
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From page 27... ...
Piezoelectric Films Most large-force, large-deflection actuation materials are ferroic ceramics or metals with complex domain structures that are poised on an instability to give a large mechanical response to external fields or forces. Piezoelectric actuators made from ferroelectric PZT (PbZr~ xTixO3)
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From page 28... ...
By selectively etching the shape-memory film and the silicon substrate, SMA microactuators have also been explored for use as electrically driven microvalves. The control of film composition and properties has proven difficult in sputter-deposited films, however, and further study of deposition techniques is needed.
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From page 29... ...
Processing Advances in the use of new materials, novel powdersynthesis methods, and ceramic integration are being made in electronic ceramics at scales much greater than those typical of MEMS. Monolithic multifunctional components take advantage of four existing technologies: thick-film methods and materials; multilayer ceramics capacitor processes; cofired package concepts; and thin-film deposition on silicon and other substrates.
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From page 30... ...
FILMS FOR USE IN SEVERE ENVIRONMENTS: SILICON CARBIDE AND DIAMOND Applications have been identified in the automotive, electrical, and nuclear industries for MEMS sensors, actuators, and associated electronics that can operate in high-temperature TABLE 3-1 Potential Electroceramic Sensor Materials and severe environments (e.g., car engines, auto tires, nuclear reactors, and nuclear waste storage facilities)
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From page 31... ...
Many of the deposited films can subsequently be patterned using IC-based equipment and methods. Other surface modification approaches for specific applications, such as biocompatibility, include designing bioactive coatings via protein engineering (Martin, Jiang, and Buchko, 1997~.
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From page 32... ...
Advances in thin-film technologies have enabled the deposition of electroceramic components for the fabrication of sensor and actuators, capacitors, resistors, and magnetic materials on a variety of substrate materials. The deposition techniques discussed in this chapter offer the means to produce thin films with a variety of tailorable properties and characteristics.
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From page 33... ...
The characterization and testing of MEMS materials should be an area of major emphasis. Studies that address fundamental mechanical properties (e.g., Young's modulus, fatigue strength, residual stress, internal friction)
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