Study of structural and electrical properties of ferroelectric HZO films obtained by single-target sputtering

Abstract

In this work, we study the structural and electrical properties of Hafnium Zirconium Oxide (HZO) thin films deposited by Hf0.5Zr0.5O2 single-target sputtering to fabricate a TiN/(14-/22 nm-thick) HZO/TiN stack. The structural analysis of the HZO thin films performed by in situ x-ray diffraction upon thermal annealing shows the formation of the HZO orthorhombic phase at annealing temperatures as low as 370 °C. X-ray photoelectron spectroscopy interestingly reveals an identical chemical composition of the deposited HZO thin films and the sputtered target, i.e., an Hf:Zr ratio of 1:1. The current–voltage characteristic of the TiN/HZO/TiN stack shows a current density of 10−5 A/cm2 at an applied electric field of 1 MV/cm, which, being rather low, gives a strong indication of the good electrical quality of the HZO layer. Finally, a butterfly-like capacitance–voltage loop is obtained on the TiN/HZO/TiN stack, indicating a ferroelectric behavior of the HZO layer.