Electroceramic-Based MEMS

The concept of micromachining of silicon to form micron-scale structures such as cantilevers, free-standing bridges, membranes, and channels and its combination with microelectronics fabrication methodology and technology has resulted in the em- gence of a new category of functional systems called MEMS (microelectomechanical systems). MEMS are miniature systems containing devices or arrays of devices that combine electronics with other components such as sensors, transducers and actuators, and are fabricated by IC (Integrated Circuits) batch processing techniques. The ?eld of electroceramics (inorganic, non-metallic materials, often polycr- talline, with useful electrical and other functional properties) provides a vast number of active materials for sensors, actuators, and electrical and electronic components. Electroceramic thin ?lms can add therefore many useful functionalities to MEMS. At the same time, because the fabrication of ceramics is commonly a high temperature process that often necessitates an oxygen containing atmosphere, because most cer- ics are inert and corrosion resistant, and because the properties of electroceramics are verysensitivetotheprocessingconditions, theintegrationofelectroceramiclayersonto silicon or other substrates and their patterning into functional elements need complex technologies that are still under development. This situation is re?ected in the current positionofelectroceramic-basedMEMSinthemarket: Whilethepotentialisexcellent, ?rst devices are being commercialized only these present days.

The book is focused on the use of functional oxide and nitride films to enlarge the application range of MEMS (microelectromechanical systems), including micro-sensors, micro-actuators, transducers, and electronic components for microwaves and optical communications systems. Applications, emerging applications, fabrication technology and functioning issues are presented and discussed. The book covers the following topics:

Part A: Applications and devices with electroceramic-based MEMS:

Chemical microsensors

Microactuators based on thin films

Micromachined ultrasonic transducers

Thick-film piezoelectric and magnetostrictive devices

Pyroelectric microsystems

RF bulk acoustic wave resonators and filters

High frequency tunable devices

MEMS for optical functionality

Part B: Materials, fabrication technology, and functionality:

Ceramic thick films for MEMS

Piezoelectric thin films for MEMS

Materials and technology in thin films for tunable high frequency devices

Permittivity, tunability and loss in ferroelectrics for reconfigurable high frequency electronics

Microfabrication of piezoelectric MEMS

Nano patterning methods for electroceramics

Soft lithography emerging techniques

The book is addressed to engineers, scientists and researchers of various disciplines, device engineers, materials engineers, chemists, physicists and microtechnologists who are working and/or interested in this fast growing and highly promising field.

The publication of this book follows a Special Issue on electroceramic-based MEMS that was published in the Journal of Electroceramics at the beginning of 2004. The ten invited papers of that special issue were adapted by the authors into chapters of the present book and five additional chapters were added.