IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Thin Films Thursday Sessions
       Session TF-ThA

Paper TF-ThA7
Influence of the Growth Conditions of AlN Films by Laser Ablation

Thursday, November 1, 2001, 4:00 pm, Room 123

Session: Emerging Thin Film Techniques
Presenter: A. Basillais, GREMI, France
Authors: A. Basillais, GREMI, France
C. Boulmer-Leborgne, GREMI, France
J. Perriere, GPS, France
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The pulsed laser ablation of targets in vacuum or in a reactive ambient gas (especially for oxide layer) is a very popular method for growing thin films with complex compositions and various properties. But the reliability of the pulsed laser deposition technique needs a wider understanding of thin film growth for nitride films. In this study we report AlN thin film growth by pulsed laser ablation of Al target in N2 reactive ambient gas compared to laser ablation of AlN target in vacuum or N2 gas. An approach of AlN film grown on Si(100) and Al2O3 substrates is studied. The best experimental conditions are defined in relation with film quality deduced from surface analysis (RBS, NRA, XPS, XRD, MEB). The influence of process parameters such as nature of the target, laser energy density and nitrogen partial pressure on the composition, chemical nature and structure of the films has been investigated. The main problem in AlN film growth was the oxygen incorporation. The origin of this contamination and the mechanisms of incorporation were studied, and the crucial parameter was found to be the residual pressure during ablation. Due to the difference in chemical reactivity between O and N, it is necessary to increase the density of atomic nitrogen to obtain pure AlN films. Thus, a RF discharge device was added allowing a better nitrogen molecule dissociation. Finally the hexagonal AlN phase can be formed in the laser deposited films. Highly textured films presenting epitaxial relationships with (001) Al2O3 substrates can be grown with only 5% oxygen contamination. The plasma plume investigation by emission spectroscopy allows the reactive species kinetics study for AlN growth. A secondary discharge device is mounted on the substrate to study the dark zone where there is no more plasma plume emission.