Process dependency of radiation hardness of rapid thermal reoxidized nitrided gate oxides

The radiation hardness of MOS capacitors with various reoxidized nitrided oxide (RNO) structures was studied by changing the duration of rapid thermal processes during sample preparation and by applying irradiation-then-anneal (ITA) treatments on samples after preparation. It was found that the initial flatband voltage and midgap interface trap density of MOS capacitors exhibit turnaround dependency on the total time of nitridation and reoxidation processes. For samples with nitrided oxide (NO) structures, the radiation-induced variations of the above parameters are also turnaround-dependent on nitridation time. However, when the reoxidation process is performed, the radiation hardness for all samples is gradually improved with increasing reoxidation time no matter when the nitridation time. The most radiation-hard process for RNO structures is suggested. Finally, it was found that when ITA treatments are applied on samples after preparation, their radiation hardness is much improved