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Formation of AlxOyNz Barriers for Advanced Silver Metallization

Published online by Cambridge University Press:  17 March 2011

Y. Wang  and
T.L. Alford
Y. Wang
Affiliation:
Department of Chemical, Bio, and Materials Engineering NSF Center for Low Power Electronics Arizona State University, Tempe, AZ 85287-6006, USA
T.L. Alford
Affiliation:
Department of Chemical, Bio, and Materials Engineering NSF Center for Low Power Electronics Arizona State University, Tempe, AZ 85287-6006, USA
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Abstract

Silver has been explored as a potential candidate for future advanced interconnects due to its lowest electrical resistivity, when compared with Al and Cu. As in the case of Cu metallization, an additional layer between the Ag film and underneath dielectric is necessary in order to improve adhesion and to block the diffusion of Ag atoms. In this study, thin aluminum oxynitride (AlxOyNz) diffusion barriers have been formed in the temperature range of 400-725 °C by annealing Ag/Al bilayers on oxidized Si substrates in ammonia ambient. Rutherford backscattering spectrometry showed that the out-diffused Al reacted with both the ammonia and oxygen in the ambient and encapsulated the Ag films. Higher process temperatures and thinner original Al layers showed to improve the resistivity of the encapsulated Ag layers. The resulting Ag resistivity values are ∼1.75 ± 0.35 µΩ-cm. The thermal stability test of these diffusion barriers showed that these barriers sustained the interdiffusion between Cu and Ag up to 620 °C at least for 30 min in either vacuum or flowing He-0.5% H2. This temperature is a 200°C improvement over previously reported values for the self-encapsulated Cu and Ag films. X-ray diffraction spectra showed no formation of any high resistive intermetallic compounds, i.e., Ag3Al, Ag2Al, and AlAg3.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 612: Symposium D – Materials, Technology & Reliability for Advanced Interconnects.. , 2000 , D9.6.1
Copyright
Copyright © Materials Research Society 2000

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