Preparation of AZO/ZnO/AZO/SiO/sub 2//Si thin film for FBAR

In this research, zinc oxide (ZnO) piezoelectric thin films for film bulk acoustic resonator (FBAR) applications for a high frequency range were studied by use of FTS (facing target sputtering) system, which enables to provide high density plasma, a high deposition rate at a low working gas pressure, and high quality thin films. In order to improve the crystallographic property of ZnO thin films, an AZO (ZnO:Al thin film) bottom electrode which has an equal crystalline structure to a ZnO thin film was deposited on a SiO/sub 2//Si substrate. ZnO thin films were deposited at a different oxygen gas flow ratio, and various SiO/sub 2//Si substrate temperatures were tried at a 2mTorr discharge gas pressure and a 0.8A sputtering current. The film thickness and c-axis preferred orientation of ZnO thin films were measured by /spl alpha/-step and an x-ray diffraction (XRD) instrument. In the results, we could prepare the ZnO thin film with c-axis preferred orientation of 5/spl deg/ on substrate temperature 200/spl deg/C at O/sub 2/ gas flow rate 0.7.