TABLE OF CONTENTS The fabrication of a microsystem requires the processing of a large variety of different materials in order to realize their different electronic, sensor, and actuator components. The fabrication processes of these materials should be compatible with microsystem technologies, i.e., with silicon micromachining. One possibility for the realization of sensors and actuators in microsystems is the use of smart materials that directly transduce electrical, magnetic, or thermal energy into mechanical energy or vice versa. The related physical effects are the piezoeffect, magnetostriction, or the shape memory effect.
In general, thin film technologies are an attractive approach to integrate these materials into microsystems as this approach has almost no materials limitations, offers easy down-scaling into the micrometer range by a cost-effective manufacturing technology, avoids assembly and interconnection processes, allows the protection of the microsystem by protective layers (Quandt and Holleck 1998), and provides the possibility to design new materials as, for example, metastable phases, multilayers or gradient layers. Physical vapor deposition (PVD) techniques, in particular magnetron sputtering, offer the opportunity of tailoring the constitution of the thin films. Additionally, the interaction with the substrate enables fabrication of highly textured films which, in the case of piezoelectric materials, show improved properties compared to conventional polycrystalline bulk materials. Furthermore, it can be expected that the integrated sensing features of smart film actuators e.g., the resistive effects present in all three classes of materials will provide means to realize intelligent actuators by using thin film smart materials.
Thin film actuators in the...
