Development of Film Bulk Acoustic Wave Resonator: A Review

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

“…[1][2][3][4] As bulk acoustic wave (BAW) devices operating in the GHz range, FBARs have attracted much attention due to their small size, high operating frequency and potential applications in high-frequency communication and mass-sensitive sensor areas. [5][6][7][8] As a kind of FBAR, solidly mounted resonators (SMRs) are composed of a piezoelectric layer sandwiched between electrodes and Bragg reector consisting of alternating high and low acoustic impedance quarter-wavelength thick dielectric or metallic layers. 9,10 The SMR, with good mechanical strength and excellent acoustic properties, and being closer to CMOS integration, was therefore chosen in this work.…”

Solidly mounted resonator sensor for biomolecule detections

“…However, the SAW sensors cannot achieve a higher sensitivity due to the restriction on dimension of the delay line for the interdigital transducer (IDT) and the resonant frequency (from 30 MHz to 1 GHz). 12,13 In addition, the quartz crystal microbalance (QCM) employed in BAW sensors has a mass detection limit in the order of nanograms determined from their low operation frequency (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) due to the bulk quartz substrate thickness. Thus BAW sensors do not have adequate sensitivity for the detection of small molecules in low concentrations.…”

“…Importantly FBAR operating in the GHz range can overcome the shortcomings of BAW sensors and have better performance in mass-sensitive detections. 16 In addition to the sensitivity, FBAR has several other advantages, including small in size, room-temperature operation, and mass producible. [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.…”

Hydrothermally synthesized PZT film grown in highly concentrated KOH solution with large electromechanical coupling coefficient for resonator

“…Therefore, microelectromechanical system resonators have been thoroughly studied for applications such as gas identification and biological substance detection [3,4]. A popular type of microelectromechanical system piezoelectric resonator is made by using a piezoelectric film no thicker than a few micrometres, composed of substances such as lead zirconate titanate (PZT), aluminium nitride or zinc oxide, to form a film bulk acoustic wave resonator [5][6][7][8]. The resonator converts electrical energy into acoustic energy through an alternating electric field, and its resonant frequency depends on the thickness of the piezoelectric material.…”