Theoretical and experimental investigations to obtain lower voltage electrically erasable and programmable ROM's (EEPROM's) than conventional devices have been performed. The scaled-down metal-oxide-nitride-oxide-semiconductor (MONOS) structure is proposed to realize an extremely low-voltage programmable device. The proposed scaled-down MONOS devices enjoy several advantages over MNOS devices, e.g., enlargement of the memory window, elimination of degradation phenomena, and drastic improvement in device yield. Low-voltage operation with ± 6-V supplies is demonstrated by the fabricated scaled-down MONOS transistors.