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

Paper TF-TuP8
Engineering of Porous Thin Films by Modification of Substrate Topography

Tuesday, October 30, 2001, 5:30 pm, Room 134/135

Session: Microstructure, Oxides, and Optical Properties Poster Session
Presenter: B. Dick, University of Alberta, Canada
Authors: B. Dick, University of Alberta, Canada
D. Vick, University of Alberta, Canada
T. Smy, Carleton University, Canada
M.J. Brett, University of Alberta, Canada
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A unique class of evaporated porous thin films has been developed using the technique of glancing angle deposition (GLAD). High porosity in the films is achieved by in situ control of the substrate orientation during deposition. At sub-micron scale lengths, the structure of the films consists of a "forest" of isolated columns that can be engineered into a variety of shapes. For certain envisioned applications, a regular arrangement of uniformly shaped columns may be desirable. Previous work suggests that these requirements may be difficult to achieve on planar substrates due to the column competition, extinction and thickening that occurs during growth of the film. These related phenomena arise from the fact that the advancement of the film - vacuum interface is an inherently non-linear process in which the self-shadowing mechanism plays a predominant role. We are currently investigating the degree to which order may be imposed on the film growth by means pre-patterned substrate topography. Using lithographic and embossing techniques, substrates with patterned seed arrays have been created, onto which GLAD films are then deposited. The elevated seeds serve as nucleation sites for the columns by exploiting the self-shadowing mechanism. After deposition, the films can be analyzed using atomic force and scanning electron imaging, with the dual aim of determining scaling behaviour and identifying appropriate choices of substrate and deposition parameters to produce stable column growth. Results from an experimental study supplemented by 3D-FILMS ballistic simulations will be presented. Recent examples of metal and oxide films deposited by electron beam evaporation and sputtering onto patterned and planar topography will be shown, together with a summary of our present understanding of the growth behaviour of GLAD films.