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Post-CMP Cleaning of W and SiO2: A Model Study

Published online by Cambridge University Press:  15 February 2011

Igor J. Malik ,
Jackie Zhang ,
Alan J. Jensen ,
Jeffrey J. Farber ,
Wilbur C. Krusell ,
Srini Raghavan  and
Chilkunda Rajhunath
Igor J. Malik
Affiliation:
OnTrak Systems, Inc., 1753 S. Main St., Milpitas, CA 95035
Jackie Zhang
Affiliation:
OnTrak Systems, Inc., 1753 S. Main St., Milpitas, CA 95035
Alan J. Jensen
Affiliation:
OnTrak Systems, Inc., 1753 S. Main St., Milpitas, CA 95035
Jeffrey J. Farber
Affiliation:
OnTrak Systems, Inc., 1753 S. Main St., Milpitas, CA 95035
Wilbur C. Krusell
Affiliation:
OnTrak Systems, Inc., 1753 S. Main St., Milpitas, CA 95035
Srini Raghavan
Affiliation:
University of Arizona, Dept. of Materials Science and Engineering, Tucson, AZ 85721
Chilkunda Rajhunath
Affiliation:
University of Arizona, Dept. of Materials Science and Engineering, Tucson, AZ 85721
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Abstract

Chemical-Mechanical Planarization (CMP) of SiO2 is performed using alkaline silica slurries while CMP of tungsten (W) utilizes acidic slurries with alumina as the abrasive. Proposed mechanisms for the two CMP processes, with more emphasis on SiO2-CMP, have been discussed in literature. However, much less is known about the removal mechanism of residual slurry particles from the planarized surfaces - a crucial step for subsequent device processing. We discuss the chemical and physical basis of post-CMP cleaning by double-side scrubbing using polyvinyl alcohol (PVA) brushes and show how the interactions between the wafer surface, slurry, and the brush material affect the overall cleaning efficiency. Using the zeta potential concept the common features for cleaning surfaces after SiO2-CMP and W-CMP are established and the differences between these two systems are highlighted. We present surface particle levels for two model systems as a function of cleaning chemistries and discuss their influence on post-CMP surface metal levels.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 386: Symposium O – Ultraclean Semiconductor Processing Technology and Surface , 1995 , 109
Copyright
Copyright © Materials Research Society 1995

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References

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