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Significant Enhancement of the Dielectric Constant through the Doping of CeO 2 into HfO 2 by Atomic Layer Deposition
Author(s) -
Kim WooHee,
Kim MinKyu,
Oh IlKwon,
Maeng Wan Joo,
Cheon Taehoon,
Kim SooHyun,
Noori Atif,
Thompson David,
Chu Schubert,
Kim Hyungjun
Publication year - 2014
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.12762
Subject(s) - atomic layer deposition , dielectric , materials science , nanocrystalline material , analytical chemistry (journal) , tetragonal crystal system , doping , high κ dielectric , crystallite , annealing (glass) , stoichiometry , thin film , crystallography , nanotechnology , chemistry , crystal structure , metallurgy , optoelectronics , chromatography
Films of CeO 2 were deposited by atomic layer deposition ( ALD ) using a Ce (mmp) 4 [mmp = 1‐methoxy‐2‐methyl‐2‐propanolate] precursor and H 2 O reactant. The growth characteristics and film properties of ALD CeO 2 were investigated. The ALD CeO 2 process produced highly pure, stoichiometric films with polycrystalline cubic phases. Using the ALD CeO 2 process, the effects of Ce doping into an HfO 2 gate dielectric were systematically investigated. Regardless of Ce /( Ce + Hf ) composition, all ALD Ce x Hf 1− x O 2 films exhibited constant growth rates of approximately 1.3 Å/cycle, which is essentially identical to the ALD HfO 2 growth rates. After high‐temperature vacuum annealing at 900°C, it was verified, based on X ‐ray diffraction and high‐resolution cross‐sectional transmission electron microscopy results, that all samples with various Ce /( Ce + Hf ) compositions were transformed from nanocrystalline to stabilized cubic or tetragonal HfO 2 phases. In addition, the dielectric constant of the Ce x Hf 1− x O 2 films significantly increased, depending on the Ce doping content. The maximum dielectric constant value was found to be nearly 39 for the Ce /( Ce + Hf ) concentration of ~11%.