AVS 53rd International Symposium
    Advanced Surface Engineering Thursday Sessions
       Session SE-ThA

Paper SE-ThA5
Growth Study of TiN- and TiCxNy-based Superhard Nanocomposite

Thursday, November 16, 2006, 3:20 pm, Room 2007

Session: Hard and Nanocomposite Coatings: Synthesis, Structure, and Properties
Presenter: J.E. Klemberg-Sapieha, Ecole Polytechnique, Canada
Authors: E. Bousser, Ecole Polytechnique, Canada
P. Jedrzejowski, Plasmionique
A. Amassian, Ecole Polytechnique, Canada
L. Martinu, Ecole Polytechnique, Canada
J.E. Klemberg-Sapieha, Ecole Polytechnique, Canada
Correspondent: Click to Email
Recent advances in the area of aerospace, automobile and biomedical industries, in microsystems and manufacturing of specialized industrial componentry stimulate the development of new functional coating materials and surface engineering processes that provide an ever increasing mechanical and tribological performance. In the present work, we investigate in situ and in real-time the growth of superhard ternary nanocomposite nc-TiN/a-Si3N4 and quaternary nc-TiCxNy/a-SiCN. These materials were synthesized by plasma enhanced chemical vapor deposition (PECVD) from TiCl4/CH4/SiH4/N2 gas mixtures at substrate temperature of 500oC. Using nondestructive, noncontact spectroscopic ellipsometry and appropriate ellipsometric models, we determine the variation of optical constants, film resistivity, and electron scattering time and mean free path as a function of thickness and particle size. We will show how real-time in situ measurements allow one to evaluate the evolution of the electrical properties that can be described on the basis of existing models (Thompson, Fuchs-Sondheimer, Mayadas-Shatzkes), and related to electron scattering due to phonons, point and line defects (grain boundaries), and surface effects. The films' electrical characteristics derived from optical measurements were confirmed by direct four-point evaluations, and interpreted in terms of the evolution of their microstructure and chemical composition. This approach then became the basis for a generalized microstructural model that takes into account the microstructural features including grain size, inter-grain spacing and interfaces, that are closely related to the film hardness (>50 GPa), and the highest reported H3/E2 ~ 1.8 GPa parameter characterizing resistance to plastic deformation obtained for such nanocomposite films. High resolution TEM micrographs of the evolution of the nanostructures are also presented in support of the structural model.