AVS 47th International Symposium
    Surface Engineering Tuesday Sessions
       Session SE-TuP

Paper SE-TuP11
Effect of Annealing on the Microstructure and Mechanical Property of TiN/AlN Multilayer Films Prepared by the Ion-beam Assisted Deposition

Tuesday, October 3, 2000, 5:30 pm, Room Exhibit Hall C & D

Session: Poster Session
Presenter: D.G. Kim, Kwangju Institute of Science and Technology, Korea
Authors: D.G. Kim, Kwangju Institute of Science and Technology, Korea
Y-.J. Baik, Korea Institute of Science and Technology
T.Y. Seong, Kwangju Institute of Science and Technology, Korea
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Nano-scale nitride multilayers are considerable research interests because lattice and composition modulation induces outstanding mechanical properties. Since the microstructure of nanolayered films is metastable both mechanically and thermodynamically, the thermal effect can be an important issue. In this study, we investigated the mechanical property and the thermal stability of the TiN/AlN multilayer films. TiN/AlN multilayers were prepared on (100) Si wafer by ion-beam assisted deposition (IBAD), evaporating alternatively Ti and Al metals with nitrogen and Ar ions bombardment. The multilayers were designed to have layer sequences in different bilayer periods (l) from 3.6 to 50 nm. In addition, the samples, having 3.6 and 20 nm periods, were annealed at temperatures between 800 @super o@C and 1100 @super o@C. Nano indentation hardness was employed to acquire the mechanical property of the samples. X-ray diffraction and cross-sectional transmission electron microscopy were also used to investigate the microstructural changes of the TiN/AlN multilayers with bilayer periods. The hardness for the multilayer films with ¥ë @>=@ 6 nm was around 22 GPa, whilst the hardness for the samples with ¥ë@<=@ 4 nm showed higher than 30 GPa. For the sample with ¥ë@<=@ 4 nm, a strong and narrow superlattice (111) peak was observed. However, the peaks of the hexagonal AlN and TiN were absent in this diffraction pattern. This result showed that the (111) oriented multilayer film composed of the TiN and cubic AlN was formed and these coherently bonded superlattice made the hardness with ¥ë@<=@ 4 nm sharp increase. There was no observable change in the micro-structure of the samples annealed at lower than 900 @super o@C, which preserved the discrete layered structure. But the interdiffusion of the multilayer was perceived at the higher temperature and led to deterioration of the mechanical property.