Channel Length Dependence of PBTI in High-k First RMG Gate Stack Integration Scheme

The impact of channel length (L G ) scaling on the PBTI is studied on High-k First (HKF) Replacement Metal Gate (RMG) planar devices. The threshold voltage shift (ΔV T ) due to PBTI is measured for long to short devices for different halo dose implants. It is shown that for a constant overdrive voltage (V OV ), the ΔV T due to PBTI decreases as L G scales. The rate of ΔV T decrease with L G is sensitive to halo dose variation and it reduces as halo dose increases. The underlying mechanism of ΔV T vs. L G roll-off is explained by measuring the gate current density on NMOS transistors and capacitors, and TCAD simulations.