Effects of oxidant gas for atomic layer deposition on crystal structure and fatigue of ferroelectric HfxZr1−xO2 thin films

Abstract

TiN/HfxZr1−xO2 (HZO)/TiN capacitors were prepared using two types of HZO films fabricated by atomic layer deposition using H2O or O2 plasma as an oxidant gas, and post-deposition annealing at 400 °C was performed before the TiN top-electrode fabrication. The ferroelectric orthorhombic phase was dominantly formed for the O2 plasma-based capacitor due to the strongly oxidizing source of O2 plasma, resulted in higher remanent polarization (2Pr = 20 µC/cm2) than that (13 µC/cm2) of the H2O-based capacitor. The fatigue properties for the O2 plasma-based capacitor were improved by 14 % after 106 cycles compared to the H2O-based capacitor. This could be attributed to an oxygen-rich interface reaction layer (IRL) including TiOx between the HZO film and TiN bottom-electrode for the O2 plasma-based capacitor. Based on these results, superior 2Pr and fatigue properties can be obtained using O2 plasma-based HZO films.