Effects of plasma power on ferroelectric properties of HfO2-ZrO2 nanolaminates produced by plasma enhanced atomic layer deposition

This study introduces the use of plasma-enhanced atomic layer deposition (PEALD) for growing ultrathin Zr-doped hafnium oxide (HfO2-ZrO2 or HZO) nanolaminates and the effect of radio frequency (RF) plasma power on the electrical properties of these fluorite-structure oxide films, which were employed in ferroelectric devices. The effect of the PEALD plasma power in a range of 50 similar to 200 W on the degree of the orthorhombic phase and the number of oxygen vacancies in the crystallized films can be found more clearly after the additional heat treat-ment by rapid thermal annealing (RTA). Our measurement results reveal the notable effect of plasma power in using PEALD on the growth and properties of ferroelectric oxide films. Particularly, the increased plasma power can decrease the crystallized films' remnant polarization (Pr) from 12.68 to 4.29 mu C/cm2. Besides, a relationship between the leakage current and the electronic structure causing the films' polarization is revealed. The spec-troscopically resolved band-edge electronic revealed the conversion of orthorhombic HfO2 in the laminar stacking with ZrO2 to the homogeneous HfZrxOy compounds as increasing RF power. In general, these findings show the opportunity to utilize our developed HZO nanolaminates grown by PEALD for many trending appli-cations, particularly polarization-driven memory and ferroelectric-based advanced transistors.

Automated summary

This study introduces the use of plasma-enhanced atomic layer deposition (PEALD) for growing ultrathin Zr-doped hafnium oxide (HfO2-ZrO2 or HZO) nanolaminates and explores the effect of radio frequency (RF) plasma power on the electrical properties of these oxide films. The results show the notable influence of plasma power on the growth and properties of ferroelectric oxide films, with increased power leading to a decrease in film polarization. Additionally, a relationship between leakage current and the electronic structure causing film polarization is revealed.