Advanced bulk and thin film materials for harsh environment MEMS applications

There is an increasing demand for electronic components for aerospace, the aircraft industries, sensors, and automotive applications, to name just a few, able to withstand temperatures of several centigrade degrees with lifetimes from tens to hundreds of hours. Electroacoustic devices based on acoustic wave (AW) technology must satisfy the requirements of low-cost, high-frequency, high-Q, low-loss, large piezoelectric coupling, and zero temperature coefficient of delay (TCD) to be key devices in the communication and sensor fields. These demands can be met through the appropriate choice of piezoelectric substrates crystal cut, new piezoelectric materials, and/or multilayer configurations of high speed materials with the opposite TCD. The focus of this brief review is on the recent studies of high-temperature AW devices based both on single-crystal piezoelectric substrates and on multilayered substrates (e.g., thin piezoelectric films deposited onto nonpiezoelectric substrates).