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Role of Phosphoric Acid in Copper Electrochemical Mechanical Planarization Slurries

Published online by Cambridge University Press:  31 January 2011

Serdar Aksu
Serdar Aksu*
Affiliation:
[email protected]@solopower.com, SoloPower, Inc., R&D, 5981 Optical Court, San Jose, California, 95138, United States, 408-966 5459, 408-934 1500
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Abstract

In this paper, the electrochemical behavior of copper in aqueous solutions containing phosphoric acid (H3PO4) is investigated to elucidate the role of H3PO4 in the Cu ECMP slurries. Aqueous solubility and potential-pH diagrams were constructed for copper-phosphate-water system. Good correlations were found between the diagrams and the experimental polarization data. It was found that H3PO4 might not able to sufficiently increase the solubility of copper alone. A complexing agent is needed to ensure the high solubility of copper, especially as the slurry pH and dissolved copper concentration increase. Specific conductance measurements revealed that phosphoric acid was the key constituent responsible for increasing the conductivity of the ECMP electrolyte. In situ electrochemical polarization experiments showed that the planarization mechanism during the ECMP process was similar to that observed in conventional copper CMP.

Keywords

CuCMPslurry
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1157: Symposium E – Science and Technology of Chemical Mechanical Planarization (CMP) , 2009 , 1157-E12-03
Copyright
Copyright © Materials Research Society 2009

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