Structural properties of AlN films deposited by plasma-enhanced atomic layer deposition at different growth temperatures

Crystalline aluminum nitride (AlN) films have been prepared by plasma-enhanced atomic layer deposition (PEALD) within the temperature range from 100 to 500 degrees C. A self-limiting, constant growth rate per cycle temperature window ( 100200 degrees C) was established which is the major characteristic of an ALD process. At higher temperatures (>225 degrees C), deposition rate increased with temperature. Chemical composition, crystallinity, surface morphology, mass density, and spectral refractive index were studied for AlN films. X-ray photoelectron spectroscopy (XPS) analyses indicated that besides main Al-N bond, the films contained Al-O-N, Al-O complexes, and Al-Al metallic aluminum bonds as well. Crystalline hexagonal AlN films were obtained at remarkably low growth temperatures. The mass density increased from 2.65 to 2.96 g/cm(3) and refractive index of the films increased from 1.88 to 2.08 at 533 nm for film growth temperatures of 100 and 500 degrees C, respectively. (c) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim