다양한 증착변수에 따른 AlN 박막의 물성 및 SAW 소자의 특성 분석

Abstract

AlN thin films are deposited on Si (100) and SiO2/Si substrates by using an RF magnetron sputtering method and by changing the conditions of deposition variables, such as RF power, N2/Ar flow ratio, and substrate temperature (Tsub). For all the deposited AlN films, XRD peak patterns are monitored to examine the effect of deposition condition on the crystal orientation. Highly (002)-oriented AlN films are obtained at following nominal deposition conditions; RF power = 350W, N2/Ar ratio = 10/20, Tsub = 250oC, and working pressure = 5mTorr, respectively. AlN-based SAW devices are fabricated using a lift-off method by varying the thickness of AlN layer. Insertion losses and side-lobe rejection levels of fabricated SAW devices are extracted from their frequency response characteristics, which are also compared in terms of AlN thickness and substrate. Relationships between the film properties of AlN films and the frequency responses of SAW devices are discussed. It is concluded from the experimental results that the (002)-preferred orientation as well as the surface roughness of AlN film may play a crucial role of determining the device performances of AlN-SAW devices.