Gate bias polarity dependence of charge trapping and time-dependent dielectric breakdown in nitrided and reoxidized nitrided oxides

The gate bias polarity dependence of charge trapping and time-dependent dielectric breakdown (TDDB) in nitrided and reoxidized nitrided silicon dioxides prepared by rapid thermal processing (RTP) is reported. Charge trapping during high-field injection can be reduced by rapid thermal nitridation for both substrate and gate injection. While reoxidation of nitrided oxides shows further reduction in charge trapping for substrate injection, degradation is observed for gate injection. Similar effects are observed for TDDB: reoxidized nitrided oxides show charge-to-breakdown in excess of 300 C/cm/sup 2/ for substrate injection, but less than 30 C/cm/sup 2/ for gate injection. These effects are related to the nitrogen and hydrogen profiles in the oxides. By tailoring the process conditions, a symmetric behavior of NO and RONO films with low charge trappings and Q/sub BD/ in excess of 50 C/cm/sup 2/ is possible, making them attractive as long-lifetime dielectrics from EEPROM (electrically erasable programmable ROM) and flash EEPROM technologies.<
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