Research on Hot Carrier Injection Optimization of 28HKMG Technology

With the aggressive scaling down of the gate dielectric and introducing of metal gate, reliability issues especially NBTI (Negative Bias Temperature Instability) and HCI (Hot Carrier Injection) become serious challenges. In this study, the critical role of metal gate work function metal (WFM) removing process is investigated in 28 nm HKMG technology. It's found that HCI performance of IO NMOS is dominated by the integrity of metal gate film stacks, which is much more influential than implant profile modulation as commonly used to solve HCI issue in 28 nm Poly SiON technology. And then, we propose an aluminum diffusion of metal gate and dipole formation model to explain this phenomenon.