AVS 52nd International Symposium
    Advanced Surface Engineering Monday Sessions
       Session SE-MoM

Paper SE-MoM3
Effect of Momentum Per Arriving Atom on nc-TiN/a-Si@sub x@N@sub y@ Nanocrystalline Composite Thin Film Properties in a Pulsed DC Magnetron Sputtering System

Monday, October 31, 2005, 9:00 am, Room 201

Session: Nanocomposites and Coatings with Enhanced Thermal Stability
Presenter: P. Sunal, The Pennsylvania State University
Authors: P. Sunal, The Pennsylvania State University
M.W. Horn, The Pennsylvania State University
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The mid-frequency pulsed dc range of 50-250 kHz was used to co-sputter nanocrystalline-TiN/a-Si@sub x@N@sub y@ films. A combinatorial process was performed in a reactive nitrogen environment from pure Ti and Si targets. An asymmetric bipolar pulsing frequency affects the plasma properties and results in a change in the density and energy of arriving ions at the growing film surface. The plasma potential, electron density, and electron temperature have been determined using a Langmuir probe and used with ion specie results from an energy resolved mass spectrometer to calculate the momentum per arriving atom. Using nanoindentation, the reduced modulus and hardness of the films were characterized and related to the plasma properties during deposition. The momentum per arriving atom shows threshold values for changes in the morphology, which result in different mechanical properties. Finally, the plasma properties were studied against the sputter pressure. At higher pulsing frequencies, the plasma potential increases causing energetic bombardment which yields smaller nanocrystal diameters and a stronger (200) preferred crystallographic orientation. Oxygen contamination of the thin films leads to degradation of the film properties and was investigated by using a silicon nitride capping layer to hermetically seal the film before leaving vacuum.