Metrology and physical mechanisms in new generation ionic devices Introduction Filamentary Based Resistive Switching Nanoscaled Electrical Characterization Conductive Filaments: Formation Observation and Manipulation Three Dimensional Filament Observation Reliability Threats in CBRAM Conclusions and Outlook The thesis presents the first direct observations of the 3D shape size and electrical properties of nanoscale filaments made possible by a new Scanning Probe Microscopy based tomography technique referred to as scalpel SPM. Using this innovative technology and nm scale observations the author achieves essential insights into the filament formation mechanisms improves the understanding required for device optimization and experimentally observes phenomena that had previously been only theoretically proposed