Study of pillar microstructure formation with anodic oxides

In present paper, the fabrication of pillared microstructures by means of multistep anodization of Ta/Al film structure on ceramic and silicon (100) substrates is described. The main characteristics of these structures, obtained by electron microscopy, are presented. Information on geometrical parameters of porous host and pillar microstructure elements has been obtained. The depth:diameter ratio ('aspect ratio') for investigated composition was 1.7-4.0. The transport numbers T-Ta(5+) = 0.4 and T-Al(3+) = 0.25 for the anodizing process of two-layered Ta/Al film structure have been obtained. The features of ion transport in thin film Ta/Al system under anodization are presented, and two versions of the process of pillar growth through porous Al2O3 are proposed. The scheme of the additive process for functional layer formation on the base of combined anodic oxides is proposed, which may be used, in particular, for fabrication of light-emitting structures with nanosized elements. (C) 1998 Elsevier Science S.A. All rights reserved.