Lateral-field-excited thin-film Lamb wave resonator

Abstract

The basic principles and technology for the development of lateral-field-excited Lamb acoustic wave resonators on sputter-deposited c-oriented thin aluminum nitride films are presented. The experimental results demonstrate that Lamb waves can be successfully used as an alternative to high-velocity surface acoustic waves.

Piezoelectric aluminum nitride thin films for microelectromechanical systems

“…Practically, most conventional MEMS devices that used to be made out of silicon have recently been reproduced (in most cases with enhanced performance) by using AlN thin-fi lm piezoelectric technology. For example, resonators, [2][3][4][5] fi lters, [6][7][8] switches, [9][10][11] energy harvesters, [12][13][14] ultrasonic transducers, 15,16 microphones, 17,18 strain sensors, 19 chemical sensors, 20 and accelerometers 21 have been demonstrated using AlN thin fi lms. This article reviews MEMS development using AlN, with a particular focus on RF applications and the development of…”

Flexible Surface Acoustic Wave Device with AlN Film on Polymer Substrate

“…The Al underlay enhances the electromechanical coupling coefficient as an electric field can be induced between the IDT electrodes and the Al underlay [10]. Moreover, the c-axis-oriented thin AlN films have relatively large thicknesses at about d = 0.2λ, where λ is the acoustic wavelength; therefore, the detected acoustic waves are the symmetrical S 0 Lamb waves which theoretically have the acoustic wave velocity near 10,000 m/s [11][12][13] in AlN. The velocity of the experimental results is slightly smaller than the simulated and theoretical results, possibly due to the defects of the AlN film and the slow-down effects by the Al-coated polyimide substrates.…”

Growth of preferentially-oriented AlN films on amorphous substrate by pulsed laser deposition

“…Aluminum nitride (AlN), with a wide direct band-gap (6.2 eV at 300 K) [1], high electrical resistance (10 9 10 11 m) [2], high thermal conductivity (up to 320 W/mK at room temperature) [3], a high acoustic propagation rate and a low transmission loss [4], offers tremendous potential for microelectronic devices, such as surface acoustic wave (SAW) devices [5], thin-film bulk acoustic resonators (FBARs) [6], contour mode resonators [7] and Lamb wave resonators [8,9]. Compared to zinc oxide (ZnO), AlN films show a higher SAW velocity (5607 m/s instead of 2682 m/s), better mechanical properties (18 GPa instead of 5 Gpa in Vickers hardness) [10], resistance to humidity, and better endurance to chemical etching [11].…”