A semiconductor device is provided that uses a floating gate to store analog- and digital-valued information for periods of time measured in milliseconds to hours. Charge is added to and/or removed from the floating gate by means of direct electron tunneling through the surrounding insulator, with the...http://www.google.fr/patents/US20040021166?utm_source=gb-gplus-shareBrevet US20040021166 - Pseudo-nonvolatile direct-tunneling floating-gate device
