Densification of thin aluminum oxide films by thermal treatments

Thin AlO(x) films were grown on 4H-SiC by plasma-assisted atomic layer deposition (ALD) and plasma assisted electron-beam evaporation at 300°C. After deposition, the films were annealed in nitrogen at temperatures between 500°C and 1050°C. The films were analyzed by X-ray reflectivity (XRR) and atomic force microscopy (AFM) in order to determine film thickness, surface roughness and density of the AlOx layer. No differences were found in the behavior of AlO(x) films upon annealing for the two different employed deposition techniques. Annealing results in film densification, which is most prominent above the crystallization temperature (800°C). In addition to the increasing density, a mass loss of ~5% was determined and attributed to the presence of aluminum oxyhydroxide in as deposited films. All changes in film properties after high temperature annealing appear to be independent of the deposition technique.