N-FET HCI reliability improvement by nitrogen interstitialization and its mechanism

In this paper, we demonstrate a new process to improve the N-FET's hot carrier lifetime more than 10 times, compared to that of traditional LDD formation process. It is composed of phosphorus (P/sub 31/) and nitrogen (N/sub 14/) co-implant through TEOS liner and followed by Si/sub 3/N/sub 4/ (SIN)/TEOS deposition. With this new method, the substrate current (Isub) can be reduced more than 2 times at the same drain current (Idsat). However, the quasi-static C-V measurement does not reveal the less interface state (Dit) generation during the stress for the capacitors with N/sub 14/ implant. Through SIMS analysis, it is found that the doping profiles of B/sub 11/ and P/sub 31/ have been modulated at the LDD region. Therefore, we consider that N/sub 14/ implant into the LDD region will enhance the transient enhanced diffusion (TED) effect, which leads to the Isub reduction and then improves hot carrier lifetime.