A comparative study of gate stack material properties and reliability characterization in MOS transistors with optimal ALD Zirconia addition for hafina gate dielectric

摘要

In this work, we investigate the influence of incorporation Zirconia (ZrO2) in gate dielectric HfO2 on electrical properties and the reliability of nMOSFET for the 28nm technology node. Detailed film physical, chemical and optical properties of Hf1−xZrxO2 as a function of Zr content were studied using HRTEM, AR-XPS, spectroscopic ellipsometer. Compared to HfO2, Hf1−xZrxO2 provides lower C-V hysteresis, Vt shift (ΔVt) and higher Time to Failure (TTF) lifetimes are achieved with Zr incorporation in an ALD Hf1−xZrxO2/SiO2 gate stack. 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 Zr incorporation.