Electromigration in copper interconnects is a prominent challenge for the introduction of new technologies and materials at constantly shrinking feature sizes. Physical failure analysis by means of FIB, SEM, TEM, etc. are important methods to support reliability monitoring and process development. Focus will be on SEM in situ degradation experiments of copper interconnects and failure analysis of post mortem EM test samples. A detailed description of methodology/experimental setup of the SEM in situ experiments as well as case studies for different technological approaches will be given. The use of FIB, SEM, TEM as well as other methods for physical failure analysis will be discussed from an overview perspective.