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Amorphous Ta-N as a Diffusion Barrier for Cu Metallization

Published online by Cambridge University Press:  27 July 2011

Neda Dalili ,
Qi Liu  and
Douglas G. Ivey
Neda Dalili
Affiliation:
Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2V4
Qi Liu
Affiliation:
Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2V4
Douglas G. Ivey
Affiliation:
Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2V4
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Abstract

Amorphous Ta-N thin films (14 and 62 nm thick) are deposited on Si substrates by reactive magnetron sputtering followed by Cu film deposition. The interlayer reaction and failure mechanism of the annealed metallization stacks are investigated by resistance measurements, xray diffraction (XRD) and detailed electron microscopy analysis accompanied with electron energy-loss spectroscopy (EELS). Amorphous Ta-N crystallizes at 600°C by a polymorphous transformation to Ta2N. The crystallized Ta2N barrier prevents Cu-Si interaction and intermixing up to 700-800°C, depending on the barrier thickness. Copper appears to be the main diffusing species and reacts with Si at the Ta-N/Si interface to form η˝-Cu3Si. Local Cu-Si reaction enhances the formation of TaSi2 precipitates. Silicon also diffuses, though at a much slower rate, to the surface and reacts with Cu. Local oxidation of Cu3Si occurs upon exposure to air, accompanied by SiO2 formation.

Keywords

amorphousbarrier layerthin film
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1335: Symposium O – Materials, Processes, and Reliability for Advanced Interconnects for Micro- and Nanoelectronics , 2011 , mrss11-1335-o06-03
Copyright
Copyright © Materials Research Society 2011

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