Reoxidized nitrided oxide for radiation-hardened MOS devices

A 37-nm reoxidized nitrided oxide has been developed that exhibits zero interface-state density increase, less than -1.5-V midgap voltage shift, and less than 5% degradation in inversion layer mobility after irradiation to 50 Mrad(SiO₂) with ±5 V applied to the gate. Bias annealing studies demonstrate that midgap voltage-shift recovery is more rapid than in conventional hardened oxide, indicating that these dielectrics will compare even more favorably with hard oxide at lower dose rates. The experiments also indicate that the density of hole traps in reoxidized nitrided oxide is sharply peaked at both interfaces and that the same species of trap dominates trapping at both interfaces