ABSTRACT
This chapter describes strain transducers which consist of a piezoelectric medium coupled directly to an insulated-gate field-effect-transistor structure. It also describes the piezoelectric thin-film transducer. The chapter deals with the design and the fabrication technology of the piezoelectric double-diffused MOS transducer. It discusses the theory of its operation and its measured performance. The chapter considers the temperature stability of the piezoelectric diffused MOS (PI-DMOS) transducer. In principle, the physical constants (elastic, piezoelectric, and dielectric) of the piezoelectric medium have negligible temperature coefficient. The main instability of PI-DMOS transducer then comes from the associated D-MOS structure in the substrate silicon which can be minimized by the proper choice of electrical operating condition. In practice, the long-term and short-term instabilities mainly come from the ZnO piezoelectric film. A preliminary result has shown that the strain, sensitivity of the device is constant over a temperature range from -68° to 150°C when the preventative steps are taken.
