Process-induced NBTI-imbalance of high-k/metal-gate deep-submicron CMOS

摘要

Negative bias temperature instability (NBTI) is a critical reliability concern for deep-submicron high-k metal-gate p-MOSFETs. This paper reports the impact of aggressive junction-depth scaling with laser spike annealing (LSA) superactivation on NBTI-imbalance. The testbed device simulated in this work incorporates advanced process steps of shallow trench isolation (STI) with intrinsic stress, high-k metal gate, dipole charge, stress engineering with epi-SiC and epi-SiGe pockets and dual stress liner (DSL) on-state drain current improvements for gate-first CMOS processing. The results indicate that as the laser annealing decreases and dielectric thickness increases, the drain current would be further reduced. The increase of 100 °C in laser spike annealing temperature yields ∼2 to 5 times leakage reduction. It is also investigated that thin HfO layers with lower barrier energy leads to higher and faster occupation of the charged trap state during charging phase. Energy transition from E' center to neutral precursors state with lower LSA temperature leads to a lower occupation of the charged trap, thus responsible for faster neutralization. A correlation of the time dependency for the charged trap concentration, interfacial density and the drain current is observed with ∼10% remarkable current degradation due to the trap accumulation. The measured ΔVth reduced for higher laser-induced high activation of the dopant thus is considered for the evaluation of the device performance.