Atomic Layer Deposition of La:Hf0.5Zr0.5O2 Thin Films with Abnormally High Dielectric Permittivity for Memory and Logic Devices

• Published in: Russian journal of applied chemistry 2023-05, Vol.96 (5), p.579-587
• Main Authors: Chernikova, A. G., Kozodaev, M. G., Markeev, A. M.
• Format: Article
• Language: English
• Subjects: Atomic layer epitaxy; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Industrial Chemistry/Chemical Engineering; Inorganic Synthesis and Industrial Inorganic Chemistry; Lanthanum; Leakage current; Memory devices; Orthorhombic phase; Permittivity; Random access memory; Thin films; Zirconium dioxide
• ISSN: 1070-4272; 1608-3296
• DOI: 10.1134/S1070427223050105

Ultrathin (~10 nm) functional layers of a high-k dielectric, Hf 0.5 Zr 0.5 O 2 (HZO), precision-doped with lanthanum, were prepared by molecular layering (atomic layer deposition), and capacitor structures based on them were formed. Such doping suppresses the formation of the equilibrium monoclinic phase in HZO and leads to the formation of metastable tetragonal/orthorhombic phases. Electrophysical measurements demonstrate signs of the formation of a morphotropic boundary between these phases and abnormally high, for dielectrics based on HfO 2 /ZrO 2 , relative dielectric permittivity ( k ~ 58). This quantity consists of the structure post-treatment conditions, namely, on the rapid thermal anneal (RTA) temperature. The maximal dielectric permittivity is reached at the RTA temperature of 550°С, with low leakage currents,