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Measurement of Electroplated Copper Overburden for Advanced Process Development and Control

Published online by Cambridge University Press:  15 March 2011

Joshua Tower ,
Alexei Maznev ,
Michael Gostein  and
Koichi Otsubo
Joshua Tower
Affiliation:
Philips Advanced Metrology Systems, Inc., 12 Michigan Drive, Natick, MA 01760, USA
Alexei Maznev
Affiliation:
Philips Advanced Metrology Systems, Inc., 12 Michigan Drive, Natick, MA 01760, USA
Michael Gostein
Affiliation:
Philips Advanced Metrology Systems, Inc., 12 Michigan Drive, Natick, MA 01760, USA
Koichi Otsubo
Affiliation:
Philips Advanced Metrology Systems, Inc., Kohnan, Minato-ku, Tokyo 108-8507, Japan
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Abstract

We used a non-contact metrology system based on laser-induced surface acoustic waves to evaluate the thickness uniformity of electroplated copper. Several wafers were prepared using different plating conditions that affect the copper overburden thickness and uniformity. Measurements of overburden were made on a variety of pattern features including trench arrays of several pattern densities, solid bond pads, and the surrounding field area. In general, the overburden was found to be thicker above the arrays of narrow linewidth, as compared to the surrounding field. However, the magnitude of this “mounding” effect is dependent on the plating process, pattern density, and position on the wafer. For example, as the accelerator in the plating solution increases, the mounding on a 50% density line array varies from zero to 5000 Angstroms. Under all plating conditions used, the mounding was found to be progressively higher as the pattern density of the array increases (in the range of 20% to 50% copper). The solid pads were found to have conformal filling, in all cases. It was also found that the overburden in the field area is reduced as the adjacent mounding increases, presumably because the reactant in the plating bath becomes depleted in the vicinity of the high overburden regions above the arrays.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 816: Symposium K – Advances in Chemical-Mechanical Polishing , 2004 , K4.10
Copyright
Copyright © Materials Research Society 2004

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References

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