Investigation of Hf₀.₅Zr₀.₅O₂ Ferroelectric Films at Low Thermal Budget (300 °C)
Saifei Dai, Junshuai Chai, Jiahui Duan, Jinjuan Xiang, Kai Han, Yanrong Wang, Hao Xu, Jing Zhang, Xiaolei Wang, Wenwu Wang
Abstract
This study demonstrates annealing-free TiN/Hf0.5Zr0.5O2 (HZO)/TiN (MFM) ferroelectric (FE) capacitors using a low thermal budget process (300 ° C), without post deposition annealing (PDA) or post metal annealing (PMA). The remnant polarizations (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2{P}_{\text {r}}$ </tex-math></inline-formula>) are 17.6 and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$21.8~\mu $ </tex-math></inline-formula> C/cm2 at the atomic layer deposition (ALD) temperatures (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${T}_{\text {dep}}$ </tex-math></inline-formula>) of 280 ° C and 300 ° C, respectively. The in-plane stress induced by the distorted TiN electrode could be the origin contributing to the emergence of low-thermal-budget ferroelectricity. In addition, as the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${T}_{\text {dep}}$ </tex-math></inline-formula> decreases, there is a reduction in crystallinity, orthorhombic phase (o-phase) composition, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{\text {r}}$ </tex-math></inline-formula>, dielectric permittivity (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\kappa $ </tex-math></inline-formula>), and leakage current (J), leading to an enhancement in reliability. The demonstration of annealing-free ferroelectricity at temperatures as low as 300 ° C is helpful for the back-end-of-line (BEOL) process and the reliability of FE nonvolatile memory.