Gate-Stack Engineered NBTI Improvements in Highvoltage Logic-For-Memory High-ĸ/Metal Gate Devices

Abstract

Potential solutions for the reliability challenges of high-kmetal gate (HKMG) integration into DRAM high-voltage peripheral logic devices are reported. A detailed study of Negative Bias Temperature Instability (NBTI)-degradation, supported by physical analysis, assessing the impact of various tuning components within the stack (interface layer, high-k fluorination and/or cap, metal gate) is presented. The presence of Nitrogen throughout the HKMG stack can originate either from high-k processing or metal-nitride gate electrode. It is shown that preventing nitrogen diffusion towards the Si/SiO2 interface region, together with AIOx(and F) incorporation at the HKMG interface, can tune device threshold voltage and modulate access to donor trap-defect bands. The result of these effects is a vast improvement in NBTI performance.