Demonstration of Robust Breakdown Reliability and Enhanced Endurance in Gallium Doped HfO<sub>2</sub> Ferroelectric Thin Films
Teng Huang, Yuchun Li, C. Chen, Xiaoxi Li, Ze-Yu Gu, David Wei Zhang, Xiaona Zhu, Hong-Liang Lü
Abstract
In this letter, gallium doped HfO2(Ga:HfO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{2}}{)}$ </tex-math></inline-formula> ferroelectric capacitors were fabricated and characterized. It is demonstrated that the W/Ga:HfO2/W capacitors under 650 °C rapid thermal annealing achieved a comprehensively good ferroelectricity, including a large remnant polarization ( <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> of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$32.0~\mu \text{C}$ </tex-math></inline-formula> /cm2 and a small coercive electric field ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{\text {c}}{)}$ </tex-math></inline-formula> of 0.9 MV/cm. Moreover, the devices exhibit robust breakdown reliability including high breakdown electric field ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{\text {BD}}{)}$ </tex-math></inline-formula> (>4.5 MV/cm), and large breakdown voltage (>2.7 V) for 10-year time-dependent dielectric breakdown (TDDB) lifetime. Moreover, the robust endurance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{10}}{)}$ </tex-math></inline-formula> was achieved in W/Ga:HfO2/W capacitors under 1 MHz loading. Such improvements were mainly attributed to the decreased <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{\text {c}}/{E}_{\text {BD}}$ </tex-math></inline-formula> ratio from Ga effectively doping, which lowered the probability of breakdown during cycling. This work provides the perspective to optimize the reliability HfO2-based ferroelectric devices through doping engineering.