Interdiffusion and crystallization in HfO2/Al2O3 superlattices

The interplay of interdiffusion and crystallization in HfO2/Al2O3 superlattices during spike annealing at 1050 °C was studied using x-ray reflectivity and x-ray diffraction. A transition in thermal stability was found as a function of HfO2 thickness between 2.3 and 3.2 nm. This transition is due to...

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Bibliographic Details
Published in:Applied physics letters 2009-08, Vol.95 (9)
Main Authors: Adelmann, C., Kesters, J., Opsomer, K., Detavernier, C., Kittl, J. A., Van Elshocht, S.
Format: Article
Language:English
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Summary:The interplay of interdiffusion and crystallization in HfO2/Al2O3 superlattices during spike annealing at 1050 °C was studied using x-ray reflectivity and x-ray diffraction. A transition in thermal stability was found as a function of HfO2 thickness between 2.3 and 3.2 nm. This transition is due to a crossover of HfO2 crystallization and amorphous HfO2/Al2O3 interdiffusion kinetics. For thin HfO2, amorphous HfO2 and Al2O3 interdiffuse and subsequently crystallize as HfAlOx into a cubic-HfO2-like phase. For thicker HfO2, HfO2 layers crystallize individually into the monoclinic phase. As a consequence, interdiffusion between HfO2 and Al2O3 is suppressed because of the immiscibility of Al2O3 in monoclinic HfO2.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.3223616