Flat band voltage control on low V-t metal-gate/high-kappa CMOSFETs with small EOT

Abstract

The unwanted high threshold voltage (V-t) is the major challenge for metal-gate/high-kappa CMOs especially at small equivalent-oxide-thickness (EOT). We have investigated the high V-t issue that is due to flat-band voltage (V-fb) roll-off at smaller EOT. A mechanism of charged oxygen vacancies formed by interface reaction was proposed to explain the V-fb roll-off effect. This interface reaction can be decreased by inserting a thin interfacial SiON and using novel low temperature process. The self-aligned and gate-first metal-gate/high-kappa CMCSFETs using these methods have achieved low V-t and good control of V-fb roll-off at small 0.6-1.2 nm EOT. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved,