Feasibility of re-oxidized nitrided oxide (RONO) as a charge-trapping medium for the non-volatile memory

We report on feasibility of a re-oxidized nitrided oxide (RONO) as a charge-trapping medium for non-volatile memory. The RONO is in situ formed by initial oxidation in wet oxygen ambient followed by NO anneal, then re-oxidation in wet O2 ambient, and has an “oxide/nitrogen-rich layer/oxide” structure. The nitrogen existing in the oxide bulk constitutes SiON bonding, and the nitrogen existing near the new formed Si-SiO2 interface constitutes Si2NO bonding. The SiON bonding due to the non-bonding site of nitrogen buried in the oxide is expected as a main bonding status important to the memory properties. MOS transistors with the RONO show the maximum memory window of 2.5 V and the memory retention of about three-years.