Al-doped and Deposition Temperature-engineered HfO₂ Near Morphotropic Phase Boundary with Record Dielectric Permittivity (~68)

Abstract

We report the realization of a HfO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> -based dielectric with the highest permittivity (~68) among all the reported works, approaching their theoretical limit of 70 [Fig. 1]. This is enabled by the use of Al incorporation in HfO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> films and the careful temperature engineering from 300 to 260 °C during the atomic layer deposition to realize morphotropic phase boundary (MPB), which provides a giant enhancement in dielectric response. With this ultra-high permittivity, our Al-doped HfO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> near MPB films deposited at 270 °C with a physical thickness of 9.4 nm exhibit an ultra-low leakage current density of 1.5×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−5</sup> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 1 V with an extremely small equivalent oxide thickness of 0.53 nm. These films are also able to endure a high operation voltage of 2.4 V for more than 5×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> cycles and 10 years at 0.01% failure rate and 0.1 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> dielectric area, holding great promise to be one of the key enablers for future ultra-low power transistors and ultra-high density memories (i.e. DRAM).