Characterization of Hf1-xZrxO2 Gate Dielectrics with 0≤x≤1 Prepared by Atomic Layer Deposition for Metal Oxide Semiconductor Field Effect Transistor Applications

Abstract

In this work, we investigated the influence of incorporating zirconia (ZrO2) in HfO2 gate dielectric on the electrical properties and reliability of n-channel metal oxide semiconductor field effect transistors (nMOSFETs). Detailed film physical, chemical and optical properties of Hf1-xZrxO2 as a function of Zr content were studied using high resolution transmission electron microscopy (HR-TEM), angle resolved X-ray photoelectron spectroscopy (AR-XPS), and spectroscopic ellipsometer (SE). Compared to HfO2, Hf1-xZrxO2 provides not only higher k values for further equivalent oxide thickness (EOT) scaling but also lower capacitance–voltage (C–V) hysteresis, lower threshold voltage (Vt) shift (ΔVt), and higher time-to-failure (TTF) lifetimes. Improved TTF lifetime of as high as three orders of magnitude and 35% lower Vt shift were achieved from the Hf1-xZrxO2 gate stack with x=0.8. The improved reliability of the Hf1-xZrxO2 gate dielectric is attributed to the reduced charge trapping in the Hf1-xZrxO2 gate dielectric caused by the ZrO2 incorporation.