In this paper an experimental set-up is presented that allows the Scanning Electron Microscope (SEM) in-situ investigation of electromigration phenomena in fully embedded copper interconnect structures, both from a top-down and from a cross-sectional perspective. The condition that the interconnects under test are fully embedded during the in-situ experiment is achieved using a Focussed Ion Beam (FIB) preparation technique. A SEM is equipped with a custom-made heating stage. During the experiment the void formation, growth and agglomeration process can be observed. Post-mortem cross-section analysis after the interconnect failure reveals e.g. a relationship between the microstructure of the copper contact and the non-constant growth rate of the voids.