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Polyurethane Pad Degradation and Wear Due to Tungsten and Oxide CMP

Published online by Cambridge University Press:  18 March 2011

Amy L. Moy
Affiliation:
University of New Mexico, Department of Chemical and Nuclear Engineering, 209 Farris Engineering Center, Albuquerque, NM 87131, U.S.A.
Joseph L. Cecchi
Affiliation:
University of New Mexico, Department of Chemical and Nuclear Engineering, 209 Farris Engineering Center, Albuquerque, NM 87131, U.S.A.
Dale L. Hetherington
Affiliation:
Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87123, U.S.A.
David J. Stein
Affiliation:
Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87123, U.S.A.
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Abstract

Polyurethane polishing pads are commonly used for chemical-mechanical polishing (CMP) of semiconductor wafers. Structural, chemical, and mechanical property changes of the polishing pads due to CMP are examined. Tungsten and oxide film layers are polished from the wafer surface using the polishing pad and abrasive slurry system. The polishing pad surface is flattened with polishing, and hence, reducing the effective area for slurry transport. The abrasive is used for abrading off the film from the surface. W, Al, I, and K accumulate in the polishing pad after tungsten CMP and Si accumulates after oxide CMP. Material accumulates in the pad pores and grooves. Electron Microprobe X-ray Analysis and Wavelength Dispersive Spectrometry (WDS) were used to examine the changes across the thickness of the pad. Fourier Transform Infrared Spectroscopy (FTIR) was used to determine the changes to the polyurethane isocyanate group. The reduction in the isocyanate group and increase in the hydroxyl group after tungsten CMP indicates that a hydrolysis reaction of the isocyanate to form carboxylic acid occurs.

Type
Research Article
Copyright
Copyright © Materials Research Society 2001

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References

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