Thin films grown using atomic layer deposition (ALD) are known for being continuous and nearly pinhole-free. These characteristics enable ALD films to be important in many applications such as gas or copper diffusion barriers, gate dielectrics, surface modification and functionalization layers. Few methods have been demonstrated to characterize defects in ALD films. In this study, a method to render the defects visible in Al2O3 ALD thin films on conductive substrates has been developed by growing copper bumps locally at the defect sites using electroplating. The electroplated copper can be easily observed or inspected using conventional optical- or electron-microscopy. Using this approach, the defect density in Al2O3 ALD thin films grown on nickel substrates has been shown to be as low as 38/cm(2). (C) 2009 Elsevier B.V. All rights reserved.