Research on Negative Bias Temperature Instability Effects Under the Coupling of Total Ionizing Dose Irradiation for PDSOI MOSFETs

The degradation mechanisms for pMOSFETs from a 130 nm partially-depleted silicon on insulator (PDSOI) technology under the combined effects of total ionizing dose (TID) and negative bias temperature instability (NBTI) are investigated. The TID and NBTI related degradations show an opposite trend as gate oxide scaling, which implies the different traps are activated during irradiation and NBTI stress. The radiation-induced traps can affect the NBTI effect of pMOSFET, especially for the ON bias irradiation. The irradiated I/O pMOSFET shows a smaller threshold voltage shift than the un-irradiated device under the same NBTI stress at the early stress stage. It may be contributed to the enhanced Fowler-Nordheim electron injection during NBTI stressing after ON bias irradiation. But the irradiation also increases the time exponent $n$ from 0.11 to 0.13 for Core pMOSFETs and from 0.18 to 0.20 for I/O devices. It means that the NBTI degradations become worse after ON bias irradiation in a long time scale. This phenomenon is attributed to the change of trap characteristics caused by irradiation. As a result, the NBTI lifetime of Core device is reduced by nearly three orders of magnitude and the lifetime of I/O device is reduced by five times after ON bias irradiation at the rated operating voltage.