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Effect of Al-content and Post Deposition Annealing on the Electrical Properties of Ultra-thin HfAlxOy Layers

Published online by Cambridge University Press:  11 February 2011

R. J. Carter
Affiliation:
IMEC vzw, 75 Kapeldreef, B-3001 Leuven, Belgium
W. Tsai
Affiliation:
International Sematech Assignee c/o IMEC
E. Young
Affiliation:
International Sematech Assignee c/o IMEC
M. Caymax
Affiliation:
IMEC vzw, 75 Kapeldreef, B-3001 Leuven, Belgium
J. W. Maes
Affiliation:
ASM Belgium, 75 Kapeldreef, B-3001 Leuven, Belgium
P. J. Chen
Affiliation:
International Sematech Assignee c/o IMEC
A. Delabie
Affiliation:
IMEC vzw, 75 Kapeldreef, B-3001 Leuven, Belgium
C. Zhao
Affiliation:
IMEC vzw, 75 Kapeldreef, B-3001 Leuven, Belgium
S. DeGendt
Affiliation:
IMEC vzw, 75 Kapeldreef, B-3001 Leuven, Belgium
M. Heyns
Affiliation:
IMEC vzw, 75 Kapeldreef, B-3001 Leuven, Belgium
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Abstract

Scaled HfAlxOy/SiO2 stacks down to 1.5 nm EOT have been achieved. Although the addition of Al to the HfO2 matrix can be beneficial, it is observed that the benefit of using a Hf-aluminate is compromised if the film has a high Al-content. This is observed in terms of a dielectric constant close to that of pure Al2O3 (∼ 9) and a large amount of negative fixed charge in the film (∼ 1012 cm-2). Using oxygen post deposition anneals we have been able to reduce flatband voltage shifts associated with fixed charge as well as CV hysteresis. In terms of scaling, the benefit of using a high-k material is compromised if a SiO2 layer is also present in the gate stack. Therefore, it is necessary to perform an O2 PDA at moderate temperatures or in low O2 partial pressures in order to control the thickness of the interfacial oxide layer.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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References

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