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

Abstract

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 (Delta V-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 Delta V-T due to PBTI decreases as L-G scales. The rate of Delta V-T decrease with L-G is sensitive to halo dose variation and it reduces as halo dose increases. The underlying mechanism of Delta V-T vs. L-G roll-off is explained by measuring the gate current density on NMOS transistors and capacitors, and TCAD simulations.