Interface diffusion in Cu/Ru/TaN/Si stacks was investigated at different temperatures with and without electric field. It was found that electric field annealing accelerated the interface diffusion of Cu/Ru/TaN/Si. The accelerated interface diffusion is attributed to the accelerated mobility of vacancies and atoms by external electric field. A stronger accelerating effect was found on Ru/TaN interface, which resulted from accelerated N atom diffusion and the polarization of vacancies in TaN layer. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.023206esl] All rights reserved.