Atomic layer-deposited (HfZrO4)1 − x(SiO2)x thin films for gate stack applications

Abstract

Hafnium‑zirconium silicate (HfZr-silicate, (HfZrO4)1−x(SiO2)x) thin films were developed for advanced gate stack applications by incorporating Si atoms into virgin hafnium‑zirconium oxide (HfZrO4) via atomic-layer deposition, yielding films with varying Si content (x=0.10, 0.15, and 0.20). Electron conduction behavior was responsible for a reduction in the gate leakage current of HfZr-silicate compared to pure HfZrO4 films and was clearly explained by a conduction-electron generation model. Furthermore, HfZr-silicate-based structures exhibited less charge trapping and featured improved interfacial stability when in contact with Si substrate compared to virgin HfZrO4, although they both experienced bias and thermal stress. These phenomena were associated with the formation of an interfacial layer (IL) between virgin HfZrO4 and the Si substrate, while there was no IL for the HfZr-silicate. With regard to the electrical properties of the films with varying Si incorporation, film with 15% SiO2 was recommended as a high dielectric constant candidate due to its superior electrical properties and outstanding durability.