CMOS integrated ZnO thin film bulk acoustic resonator with Si3N4 susceptor layer for improved IR sensitivity

Microelectromechanical sensors (MEMS) offer a new way of measuring temperature and infrared (IR) radiation, through measurements of total optical energy, overcoming the obstacles associated with narrow bandgap semiconductor detectors[1]. Specifically, Thin Film Bulk Acoustic Resonators (FBAR) offers a versatile MEMS technology based on resonant devices fabricated using piezoelectric materials [2]. With the addition of an absorbing susceptor and the use of zinc oxide (ZnO) as the piezoelectric it is possible to obtain a higher sensitivity device than previously demonstrated systems, taking advantage of ZnO's higher temperature coefficient of frequency (TCF) [3,4,5]. This work studies the improved sensing ability of an FBAR structure and ease of testing and superior parasitic performance provided in a package using an engineered high TCF FBAR in a monolithically integrated CMOS process.