A Simulation Study of Oxygen Vacancy-Induced Variability in ${\rm HfO}_{2}$ /Metal Gated SOI FinFET

Abstract

Deposition of a metal gate on high-K dielectric HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is known to generate oxygen vacancy (OVs) defects. Positively charged OVs in the dielectric affect the gate electrostatics and modulate the effective gate workfunction (WF). Count and spatial allocation of OVs varies from device-to-device and induces significant local variability in WF and V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> . This paper presents the statistical models to simulate OV concentration and placement depending on the gate formation conditions. OV-induced variability is studied for SOI FinFET, and compared against the other sources of variability across the technologies. The implications of gate first and gate last processes to the OV concentration/distribution are studied. Simulations show that with channel length and gate dielectric thickness scaling, the OV-induced variability becomes a significant concern.