Thermal stability of lanthanum in hafnium-based gate stacks

The controlled addition of La to Hf x Si 1 − x O 2 / SiO 2 / Si dielectric stacks has been shown to enable the engineering of the work function to appropriate levels when TaN or TiN is employed as the capping metal gate. Work function tuning has been suggested to be controlled by La diffusion into t...

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Bibliographic Details
Published in:Journal of applied physics 2009-09, Vol.106 (5), p.053506-053506-5
Main Authors: Medina-Montes, M. I., Selvidge, M. V., Herrera-Gomez, A., Aguirre-Tostado, F. S., Quevedo-Lopez, M. A., Wallace, R. M.
Format: Article
Language:English
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Summary:The controlled addition of La to Hf x Si 1 − x O 2 / SiO 2 / Si dielectric stacks has been shown to enable the engineering of the work function to appropriate levels when TaN or TiN is employed as the capping metal gate. Work function tuning has been suggested to be controlled by La diffusion into the Hf-based dielectric as a result of further thermal treatments. In this paper, we performed high resolution angle resolved x-ray photoelectron spectroscopy (ARXPS) studies to investigate the chemical depth profile distribution of TaN / La 2 O 3 / HfO 2 / SiO 2 / Si dielectric stacks exposed to a nitridation treatment by NH 3 at 700 ° C . The stoichiometry and distribution of the HfO 2 and SiO 2 layers was examined using a self-consistent ARXPS analysis. This study shows that La diffuses to the SiO 2 / HfO 2 interface, and that subsequent rapid thermal annealing at 1000 ° C for 5 s does not significantly change the La distribution.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.3190505