Microstructures of HfOx Films Prepared via Atomic Layer Deposition Using La(NO3)3·6H2O Oxidants

Hafnium oxide (HfOx) films have a wide range of applications in solid-state devices, including metal–oxide–semiconductor field-effect transistors (MOSFETs). The growth of HfOx films from the metal precursor tetrakis(ethylmethylamino) hafnium with La(NO3)3·6H2O solution (LNS) as an oxidant was invest...

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Published inMaterials Vol. 14; no. 23; p. 7478
Main Authors Kim, Seon Yong, Jung, Yong Chan, Seong, Sejong, Lee, Taehoon, Park, In-Sung, Ahn, Jinho
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 06.12.2021
MDPI
Subjects
atomic layer deposition
Atomic layer epitaxy
Crystal defects
Crystallites
Dielectric properties
Field effect transistors
Film growth
Grain boundaries
Hafnium oxide
hafnium oxide film
Metal oxide semiconductors
Metal oxides
Microscopy
Microstructure
Morphology
MOSFET
MOSFETs
Oxidizing agents
Semiconductor devices
Solid state devices
Surface energy
Thin films
United States > US
Japan
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Summary:Hafnium oxide (HfOx) films have a wide range of applications in solid-state devices, including metal–oxide–semiconductor field-effect transistors (MOSFETs). The growth of HfOx films from the metal precursor tetrakis(ethylmethylamino) hafnium with La(NO3)3·6H2O solution (LNS) as an oxidant was investigated. The atomic layer deposition (ALD) conditions were optimized, and the chemical state, surface morphology, and microstructure of the prepared films were characterized. Furthermore, to better understand the effects of LNS on the deposition process, HfOx films deposited using a conventional oxidant (H2O) were also prepared. The ALD process using LNS was observed to be self-limiting, with an ALD temperature window of 200–350 °C and a growth rate of 1.6 Å per cycle, two times faster than that with H2O. HfOx films deposited using the LNS oxidant had smaller crystallites than those deposited using H2O, as well as more suboxides or defects because of the higher number of grain boundaries. In addition, there was a difference in the preferred orientations of the HfOx films deposited using LNS and H2O, and consequently, a difference in surface energy. Finally, a film growth model based on the surface energy difference was proposed to explain the observed growth rate and crystallite size trends.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma14237478