Preparation of highly oriented AlN thin films on glass substrates by helicon plasma sputtering and design of experiments

Aluminum nitride (AlN) thin films were deposited by a helicon plasma sputte ring system with a radical cell. We investigated the effects of eight sputt ering control factors on the crystal orientation of the films by design of experiments and the analysis of variance (ANOVA) in order to prepare highly oriented AlN thin films on silica glass substrates. Consequently, it was p roved statistically that the distance between a target and a substrate, the sputtering pressure and the substrate temperature are significant control factors for the crystal orientation of the films. Especially, the distance is the most important factor of the eight central factors, which has not be en reported so far. On the other hand, the effects of the cathode r.f. coil power, the radical cell power, the nitrogen concentration, the sputtering time and the cathode power are not statistically significant. Moreover, a d etailed investigation of the dependence of the orientation on the three imp ortant control factors was carried out to optimize the sputtering condition s. The full width at half-maximum (FWHM) of the X-ray rocking curve of the film deposited under the optimized sputtering conditions is 2.4 degrees (si gma = 1.3 degrees). This orientation is the highest in the ALN thin films d eposited on amorphous substrates reported to our knowledge. (C) 1999 Elsevi er Science S.A. All rights reserved.