Anisotropy and texture in thin copper films -: an elastoplastic analysis

The role of elastic anisotropy on the stress inhomogeneity and effective behavior of columnar grained textured Cu thin films have been analyzed within a continuum framework. The analysis is based on a three-dimensional model of a film/substrate system. The film exhibits a fiber texture with (111), (001) and randomly oriented grains. Mainly two load cases have been considered. Biaxial loading of a film deposited on a silicon substrate and tensile loading of a film deposited on a polyimide substrate. The stress distributions in the (111) and (001) grains were generally found to be very different when subjected to biaxial loading and quite similar when subjected to tensile loading. When plastic behavior is invoked, a structural hardening effect is observed. The plastic behavior differs significantly between biaxial and tensile cyclic loading respectively. A new orientation dependent hardening law is proposed. This hardening law causes the plastic hardening behavior to be orientation dependent and scale with elastic anisotropy. The newly proposed hardening law is demonstrated on a film with small grain aspect ratio. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.