Direct scanning tunnelling potentiometric observations were made of electrochemical potential and local transport field variations near to grain boundaries, triple-points and voids in thin films. The field was highest at a void, followed by a triple-point and a grain boundary. The local transport field near to a void could be 4 orders of magnitude higher than the macroscopic field; thus indicating that the void was the most likely position for electromigration-induced failure. The field build-up for a particular type of scatterer depended upon the grain connectivity.

Field and Potential around Local Scatterers in Thin Metal Films Studied by Scanning Tunnelling Potentiometry. G.Ramaswamy, A.K.Raychaudhuri: Applied Physics Letters, 1999, 75[13], 1982-4