Enhanced Ferroelectric Properties in Hf_0.5Zr_0.5O₂ Films Using a HfO_0.61N_0.72 Interfacial Layer

Abstract

Fluorite structured ferroelectrics, such as (Hf, Zr)O2, attract much interest due to their scalability and compatibility with complementary metal‐oxide semiconductors, which make them superior to the conventional ferroelectrics. However, their reliability issues, including their limited endurance, are yet to be resolved. Such issues have been reported to be strongly correlated to the formation and drift of oxygen vacancies concentrated in the interfacial region adjacent to TiN electrodes. In this study, the effect of inserting a sacrificial HfO0.61N0.72 interfacial layer between a TiN bottom electrode and a ferroelectric Hf0.5Zr0.5O2 thin film is investigated. The insertion of the 2 nm‐thick HfO0.61N0.72 interfacial layer decreases the inclusion of the undesirable non‐ferroelectric phase by ≈60% and increases the remanent polarization by more than 30%. The reaction barrier property of the sacrificial HfO0.61N0.72 layer significantly enhances the reliability of the Hf0.5Zr0.5O2 film, and thus, improves the endurance of the film beyond 1.5 × 1011 switching cycles. This is the highest endurance among the reported values for fluorite‐structured ferroelectrics with the remanent polarization kept higher than 10 µC cm‐2.

Highly efficient voltage-controlled magnetism in HfZrO/CoFeB hybrid film and Hall device

“…The recognizable polycrystalline of HfZrO layer is a characteristic of HfO 2 -based ferroelectric materials. 15,16) To further analyze the phase structure of the HfZrO layer, a Nano Beam Diffraction (NBD) is carried out. From the diffraction pattern, we calculate the interplanar distance which is about 2.92 Å by the Gatan Digital Micrograph and the result is in accord with (111) orthorhombic phase of HfO 2 -based ferroelectric materials.…”

Atomic layer deposition of HfNx films and improving the film performance by annealing under NH3 atmosphere

“…These layers adversely interfere with FE performance, resulting in polarization degradation and reliability issues. 7–10…”

“…Kim et al reported that a thin (1–2 nm) HfO x N y ( x = ∼0.61, y = ∼0.72) interfacial layer, grown by reactive sputtering, could efficiently suppress such adverse impacts by TiN oxidation. 9 The thin interfacial layers were in situ or ex situ oxidized during their growth and subsequent atomic layer deposition (ALD) of the Hf 0.5 Zr 0.5 O 2 (HZO) FE film. This oxidized interfacial layer protected the TiN film from oxidation-induced degradation.…”

“…Owing to the favorable impact of the HfO x N y interfacial layer, the remanent polarization ( P r ) of the 10 nm-thick HZO film was improved from ∼15 to ∼20 μC cm −2 . 9…”

Gateway toward efficient and miniaturized A2B2O7-type fluorite structure-based energy storage devices

“…5 However, with the discovery of ferroelectricity in fluorite structure in 2011, modern researchers put their attention to using these materials for advanced applications because of their low dielectric constant, simple structure, low leakage current, and small unit cell volume compared to perovskite and pyrochlore materials. 6,7 Ongoing development in smart electronic devices makes fluorite structure more imperative than others to be utilized for micromechanical and fast-switching applications. 8…”