Morphology and crystallization kinetics in HfO2 thin films grown by atomic layer deposition

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Date
2003-02Author
Ho, M.-Y.
Gong, H.
Wilk, G. D.
Busch, B. W.
Green, M. L.
Voyles, P. M.
Muller, D. A.
Bude, M.
Lin, W. H.
See, A.
Loomans, M. E.
Lahiri, S. K.
Raisanen, Petri I.
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Show full item recordAbstract
We report the effects of annealing on the morphology and crystallization kinetics for the high-k gate dielectric replacement candidate hafnium oxide (HfO2). HfO2 films were grown by atomic layer deposition (ALD) on thermal and chemical SiO2 underlayers. High-sensitivity x-ray diffractometry shows that the as-deposited ALD HfO2 films on thermal oxide are polycrystalline, containing both monoclinic and either tetragonal or orthorhombic phases with an average grain size of ~8.0 nm. Transmission electron microscopy shows a columnar grain structure. The monoclinic phase predominates as the annealing temperature and time increase, with the grain size reaching ~11.0 nm after annealing at 900 �C for 24 h. The crystallized fraction of the film has a strong dependence on annealing temperature but not annealing time, indicating thermally activated grain growth. As-deposited ALD HfO2 films on chemical oxide underlayers are amorphous, but show strong signatures of ordering at a subnanometer level in Z-contrast scanning transmission electron
microscopy and fluctuation electron microscopy. These films show the same crystallization kinetics
as the films on thermal oxide upon annealing.
Subject
fluctuation electron microscopy
gate dielectric
HfO2
Permanent Link
http://digital.library.wisc.edu/1793/63502Type
Article
Citation
Journal of Applied Physics 93, 1477 (2003)