High textured AlN thin films grown by RF magnetron sputtering; composition, structure, morphology and hardness

High quality thin aluminum nitride (AlN) films have been deposited onto a silicon (10 0) substrate by radio frequency magnetron sputtering of a pure Al target using different gas (Ar, N-2) mixtures. The depositions were carried out at substrate temperatures varying from room temperature (plasma heating) up to 400degreesC. The crystalline structures were investigated by X-ray diffractometry (XRD) revealing a pronounced texture of the deposited films. Some of the compounds investigated were deposited onto a thin buffer layer of pure Al. The film surface morphology was investigated by Atom Force Microscopy (AFM) (SPM-9500J3 from Shimadzu Co), and was found to depend distinctively upon the different deposition conditions. Generally, two kinds of structures were found-a columnar one, which was densely packed or organized in planar parallel sheets, and a flat structure, (typical for mono-crystals), with rms roughness below 0.2 nm. In this paper, the influence of argon added to the sputtering gas environment on the film properties is investigated and discussed. The depth elemental distributions were calculated using 2.4 MeV He-4(+) Rutherford Backscattering Spectrometry (RBS). Finally, the mechanical characteristics were described using hardness tests. (C) 2004 Elsevier Ltd. All rights reserved.