Physical and chemical analysis of advanced interconnections using energy filtering transmission electron microscopy

Our newest method for interconnection analysis using focused ion beam (FIB) specimen thinning and energy filtering transmission electron microscopy (EFTEM) is presented. It is shown that using the site-specific capability and the controlled thinning effect of the FIB in addition with the high spatial resolution of the EFTEM technique, fast chemical analysis of materials with nanometre spatial resolution can be obtained. This is the only method for the observation of very thin diffusion barriers and interfaces in the presence of drastic topography. Application examples are given concerning firstly, the in-depth analysis of tungsten aluminum technology, barrier integrity and interdiffusion of elements near interfaces and secondly, the surface contamination of copper in copper interconnection technology with high aspect ratio contacts. In this case, photoresist spin-coating is carried out prior to FIB thinning. This method is an alternative to surface analysis techniques and offers the best spatial resolution without topography limitations.