AVS 50th International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS-MoA

Paper PS-MoA4
Reactive Sputter Deposition of Nanocrystalline Compound Thin Films with a Hollow Cathode Source Operated in a Static Mode

Monday, November 3, 2003, 3:00 pm, Room 314

Session: Plasma Sources
Presenter: A. Pradhan, University of Delaware
Authors: A. Pradhan, University of Delaware
S.I. Shah, University of Delaware
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Hollow Cathode Sources (HCS) are unique sputtering sources that sputter material from the inner surface of a cylindrical tube. Due to their geometry, HCS offer several advantages such as lack of hysteresis, low consumption of the reactive species, high plasma density and high deposition rates. We have characterized a titanium HCS for reactive deposition of titania films in static mode. In this mode the sputtering is carried out in a static gas volume. Stoichiometric films growth could be sustained even after 3 hours of continuous sputtering. This new method of reactive sputtering offers several advantages over conventional techniques such as ease of operation, lower equipment cost, lower environmental load, etc. Langmuir probe measurements were used to determine the plasma parameters in a static HCS. The plasma density was 2-3 orders of magnitude greater than that obtained in planar sputtering. The high-density plasma can be used to deposit stoichiometric nanocrystalline oxide films by negatively biasing the substrate and allowing the ion bombardment to provide the energy required for crystallization of the growing film. X Ray Diffraction (XRD) of the films grown with a substrate bias of -80V shows the presence of the rutile phase. The particle size was estimated from the XRD peak broadening to be around 20nm. The films were also characterized by X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Films were found to be nanocrystalline only when the sputtering gas was rich in oxygen. Monte Carlo simulations were carried out using SRIM program to determine the energy transferred by the ions to the growing surface. It was found that backscattered ion count was much higher in the case of O2 when compared to Ar, which could be responsible for the formation of nanocrystalline films.