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Selectivity Studies On Tantalum Barrier Layer In Copper CMP

Published online by Cambridge University Press:  01 February 2011

Arun Vijayakumar ,
Tianbao Du ,
Kalpathy B. Sundaram  and
Vimal Desai
Arun Vijayakumar
Affiliation:
Advanced Materials Processing and Analysis CenterUniversity of Central FloridaOrlando, FL 32816, U. S. A
Tianbao Du
Affiliation:
Advanced Materials Processing and Analysis CenterUniversity of Central FloridaOrlando, FL 32816, U. S. A
Kalpathy B. Sundaram
Affiliation:
Advanced Materials Processing and Analysis CenterUniversity of Central FloridaOrlando, FL 32816, U. S. A
Vimal Desai
Affiliation:
Advanced Materials Processing and Analysis CenterUniversity of Central FloridaOrlando, FL 32816, U. S. A
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Abstract

Copper metallization in sub-0.18 μm semiconductor devices is achieved by combining the dual damascence techniques followed by chemical mechanical planarization (CMP). Tantalum and its nitride have been identified as the diffusion barrier layer for copper metallization. However, the wide differences in properties between copper and tantalum layers result in selectivity problems during CMP process. The aim of this work is to obtain a better understanding on the slurry selectivity for copper and tantalum and to develop slurries with best selectivity performance. In this work, the effect of several chemical parameters (abrasive type, oxidizer type, concentration, pH etc.) was studied through static and dynamic tests using advanced electrochemical techniques and surface analysis techniques. The surface layers of the statically etched copper and tantalum discs were investigated using X-ray photoelectron spectroscopy (XPS) and surface planarity was studied using atomic force microscopy (AFM). Polishing rates results show that alumina-based slurry polished copper very well whereas tantalum removal rate was low. However, for the silica-based slurry the tantalum shows much higher removal rate than copper and better surface planarity was obtained.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 767: Symposium F – Chemical-Mechanical Planarization , 2003 , F6.3
Copyright
Copyright © Materials Research Society 2003

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