Effects of nitrogen implant on ultra-thin gate dielectric breakdown

摘要

This paper presents the nitrogen implant effects on ultra-thin gate oxide time dependent dielectric breakdown (TDDB) with the underlying mechanism studied. It is found that the nitrogen implant can improve TDDB reliability on NMOS while the corresponding gate leakage during TDDB stressing is much reduced. A deeper implantation with higher implant energy has a larger impact. In literature, the dielectric breakdown is explained by anode hydrogen release (AHR) [1] or the anode hole injection (AHI) [2] models. In this study, the experimental observation is mainly attributed to the nitrogen penetration into the gate dielectric, which then enhances the capability of electron negative trap. Detailed study shows that the nitrogen-assisted interface traps increase with nitrogen implant energy, leading to a reduced leakage current during TDDB stressing and longer time to breakdown (Tbd).