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The Influence of Ozone: Superstoichiometric Oxygen in Atomic Layer Deposition of Fe 2 O 3 Using tert ‐Butylferrocene and O 3
Author(s) -
Schneider Joel R.,
Baker Jon G.,
Bent Stacey F.
Publication year - 2020
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.202000318
Subject(s) - ozone , atomic layer deposition , hematite , oxide , iron oxide , materials science , oxygen , maghemite , chemical engineering , monolayer , inorganic chemistry , chemistry , nanotechnology , layer (electronics) , metallurgy , organic chemistry , engineering
Understanding the chemical mechanisms at play in atomic layer deposition (ALD) is critical for effective process development and expansion of ALD into more complex classes of materials. In this work, a mechanistic study of iron oxide deposited by ALD using tert ‐butylferrocene and ozone as reactants is performed. Iron oxide ALD using ozone is a useful model system for mechanistic studies due to the prevalence of ozone‐based ALD processes and the uses of iron oxide in ternary and quaternary metal oxides. Results show that saturation conditions require significantly greater exposures of both reactants than is typically reported in the literature, and growths per cycle of greater than one monolayer of Fe 2 O 3 per cycle are observed and explained. A growth mechanism is proposed whereby increased ozone exposure results in uptake of superstoichiometric oxygen into the film. X‐ray characterizations reveal the presence of excess oxygen stored near the surface of films deposited with larger ozone exposures and show that increased ozone exposures cause crystalline domain rearrangement and conversion of the film from the γ‐maghemite phase to the α‐hematite phase. The mechanism described here has implications for the wider class of ozone‐based ALD processes, and potential applications of this growth phenomenon are discussed.