Ion-beam-sputtered Ta2O5/SiO2 multi-layer stacks have been mechanically stressed to failure. The delamination failures do not occur precisely at the layer interfaces. XPS and AFM analyses indicate that the failures occur near the interfaces where SiO2 was deposited on Ta2O5. Delamination is not observed near the interfaces where Ta2O5 was deposited on SiO2. The failure location is 2-3 nm into Ta2O5 layers and can occur randomly near multiple interfaces within a test. The delamination failures were induced by performing tape pull tests over lines scribed into the multi-layer coatings. (C) 2007 Elsevier B.V. All rights reserved.