Film bulk acoustic resonator pressure sensor with self temperature reference

Abstract

A novel film bulk acoustic resonator (FBAR) with two resonant frequencies which have opposite reactions to temperature changes has been designed. The two resonant modes respond differently to changes in temperature and pressure, being the frequency shift linearly correlated to temperature and pressure changes. By utilizing the FBAR's sealed back trench as a cavity, an on-chip single FBAR sensor suitable for measuring pressure and temperature simultaneously is proposed and demonstrated. The experimental results show the pressure coefficient of frequency for the lower frequency peak of the FBAR sensors is approximately -17.4 ppm·kPa -1 , while that for the second peak is approximately -6.1 ppm·kPa -1 , both of them being much more sensitive than other existing pressure sensors. This dual mode on-chip pressure sensor is simple in structure and operation, can be fabricated at very low cost, and yet requires no specific package, therefore has great potential for applications.

The deposition and wet etching of Mg-doped ZnO films and their applications for solidly mounted resonators

“…11,12 In recent decades, owing to excellent piezoelectric property, better quality factor, and high electromechanical coupling coefficient, ZnO is becoming a very promising candidate for FBAR devices as a piezoelectric material. [13][14][15][16] However, ZnO have the drawback of low longitudinal acoustic wave velocity and low resistance, which limits its application to high sensitivity acoustic sensors. 17 Mg X Zn 1ÀX O, a ternary compound formed by alloying ZnO and MgO, has attracted more and more attention due to its special properties such as higher acoustic velocity and resistance than that of ZnO.…”

Solidly mounted resonator sensor for biomolecule detections

“…[17][18][19] Piezoelectric materials such as zinc oxide (ZnO) 20 and aluminum nitride (AlN) 21 have been used in FBAR devices for various applications owing to their high acoustic velocity, better quality factor, and high electromechanical coupling coefficient. [22][23][24] There are two types of FBARs, one with a freestanding membrane and the other solidly mounted resonator (SMR) composed of a piezoelectric thin lm sandwiched between electrodes and Bragg reector consisting of alternating high and low acoustic impedance quarter-wavelength thick dielectric or metallic layers. 25,26 By comparing and studying, the SMR with the simple fabrication, good mechanical strength, excellent acoustic properties and closer to CMOS integration was fabricated as a promising candidate for biomolecule detections.…”

Terahertz acoustic wave on piezoelectric semiconductor film via large-scale molecular dynamics simulation

“…10) FBARs have been applied to sensing devices such as pressure and mass gauges. [11][12][13] Since the bulk oscillation along the thickness direction in a µm-order thin film is known to be a stable carrier at GHz bands, an acoustic wave control with the FBAR structure is the most plausible approach to the realization of operation frequency toward the THz domain. To apply the FBAR structure to THz waves, the thickness of the film has to be on the order of nanometer.…”