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Electrical Properties of Tantalum Based Composite Oxide Films

Published online by Cambridge University Press:  22 February 2011

Hannu Kattelus
Affiliation:
VTT Semiconductor Laboratory, Otakaari 7 B, SF-02150 Espoo, Finland
Markku Ylilammi
Affiliation:
VTT Semiconductor Laboratory, Otakaari 7 B, SF-02150 Espoo, Finland
Jorma Salmi
Affiliation:
VTT Semiconductor Laboratory, Otakaari 7 B, SF-02150 Espoo, Finland
Timo Ranta-Aho
Affiliation:
VTT Semiconductor Laboratory, Otakaari 7 B, SF-02150 Espoo, Finland
Erjany Kanen
Affiliation:
VTT Semiconductor Laboratory, Otakaari 7 B, SF-02150 Espoo, Finland
Andilkka Suni
Affiliation:
VTT Semiconductor Laboratory, Otakaari 7 B, SF-02150 Espoo, Finland
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Abstract

Tantalum oxide is a widely used insulator in electronic applications requiring high permittivity. When deposited at low temperature, tantalum oxide films, however, often exhibit large leakage current. A common way to reduce leakage is to anneal the films in an ambient containing extremely reactive oxygen species, or at high temperature in dry oxygen. A different approach is to use composite oxide materials. We have studied layered tantalum based oxide films deposited by Atomic Layer Epitaxy, and observed that the leakage current is decreased by several orders of magnitude when a fraction of tantalum oxide is replaced by another oxide, such as aluminum or hafnium oxide. Leakage current density of 40 nA/cm2 in the electric field of 1 MV/cm is attained for unannealed Ta-Hf-O film deposited at 300°C. Layered composite insulators are an interesting new class of materials, and ALE proves to be a useful method for depositing them.

Type
Research Article
Copyright
Copyright © Materials Research Society 1993

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References

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