Oxide charge measurements in EEPROM devices

A method to measure “on site” programmed charges in EEPROM devices is presented. Electrical AFM based techniques (Electric Force Microscopy (EFM) and Scanning Kelvin Probe Microscopy (SKPM)) are used to probe directly floating gate potentials. Both preparation and probing methods are discussed. Sample preparation to access floating gate/oxide interfaces at a few nanometers distance without discharging the data reveals to be the key point, more than the probing technique itself.