The Fabrication and Measurement of FBAR Based on AlN and Ti/W Bragg Reflectors

Abstract

This paper describes the fabrication process of the thin film bulk acoustic resonator (FBAR) based on good quality aluminum nitride (AlN) film and the measurement of FBAR by a network analyzer. The AlN film with a highly c-axis orientation and homogeneous surface morphologies is deposited on Bragg reflectors as piezoelectric film by magnetron sputtering. The Bragg reflectors consisted of Ti and W fabricated under the resonator for acoustic isolation improves performance and compatibility of the FBAR and reduces the parasitic resistance of the electrode. The devices are packaged on tube seat and fixed on a high frequency PCB board designed specially for measurement and applications. The FBAR achieved a Q factor of 505 and k2effof 3.42% at a resonant frequency of 2.22 GHz. A high sensitivity of 4.79 kHz·cm2/ng is obtained in the FBAR, which is higher than quartz crystal microbalance.