Total Dose-induced Charge Buildup In Nitrided-oxide MOS Devices

Nitrided oxides and reoxidized nitrided oxides processed at various nitridation temperatures for various nitridation times have been irradiated. The total dose response of these nitrided oxides has been analyzed and compared to that of radiation-hard control oxides. To aid in the analysis, the charge-trapping model of Krantz et al. (1987) has been extended to include electron trapping and qualitatively applied to simulate the experimental results. Nitridation temperature was found to have a significant effect on the radiation response of thin (~ 150 A) nitrided oxides and reoxidized nitrided oxides. The data show that oxides nitrided at 1050°C and reoxidized accumulate less fixed charge (by a factor of ~2) than the control oxides. Oxides nitrided at 950°C and reoxidized accumulate substantially more fixed charge (by a factor of ~5) than the controls or any of the nitrided samples. The analysis indicates that nitridation creates neutral hole traps as well as neutral electron traps, and that reoxidation can decrease the concentration of hole and electron traps.