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.