Characterization of Hf _1-xZr _xO ₂ gate dielectrics with 0 ≤ x ≤ 1 prepared by atomic layer deposition for metal oxide semiconductor field effect transistor applications

In this work, we investigated the influence of incorporating zirconia (ZrO ₂) in HfO ₂ 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 Hf _1-xZr _xO ₂ 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 HfO ₂, Hf _1-xZr _xO ₂ provides not only higher k values for further equivalent oxide thickness (EOT) scaling but also lower capacitance-voltage (C-V) hysteresis, lower threshold voltage (V _t) shift (δ V _t), 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 Hf _1-xZr _xO ₂ gate stack with x = 0:8. The improved reliability of the Hf _1-xZr _xO ₂ gate dielectric is attributed to the reduced charge trapping in the Hf _1-xZr _xO ₂ gate dielectric caused by the ZrO ₂ incorporation.