Influence of I/O oxide process on the NBTI performance of 28 nm HfO2-based HKMG p-MOSFETs

Abstract

The NBTI (negative bias temperature instability) performance of 28nm HfO2-based HKMG (high-κ metal gate) I/O thick oxide p-MOSFETs with different I/O oxide processes is reported. The results show that the NBTI performance from ISSG (in-situ steam generation) process is better than that from the furnace Gox1 process. The NBTI dependence on the PDA (post deposition anneal) process is studied and we show that PDA can significantly improve NBTI. We investigate the influence of DPN (decoupled plasma nitridation) on NBTI; the NBTI performance from the DPN process is much better than that from non-DPN processes for the devices with the same EOT (electrical oxide thickness). Based on the experiments, we propose an extended NBTI model, which incorporates nitrogen concentration in the formula for the process with DPN. This extension provides much clearer direction on process tuning to better control the DPN dosage and the EOT to meet both process electric and reliability requirements.