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Copper CMP for Dual Damascene Technology: Some Considerations on the Mechanism of Cu Removal

Published online by Cambridge University Press:  18 March 2011

David Wei ,
Yehiel Gotkis ,
Hugh Li ,
Stephen Jew ,
Joseph Li ,
Sri Srivatsan ,
Joseph Simon ,
John M. Boyd ,
KY Ramanujam  and
Rodney Kistler
David Wei
Affiliation:
Lam Research Corporation CMP/Clean Technology 47131 Bayside Parkway Fremont, CA 94538-6517, U.S.A.
Yehiel Gotkis
Affiliation:
Lam Research Corporation CMP/Clean Technology 47131 Bayside Parkway Fremont, CA 94538-6517, U.S.A.
Hugh Li
Affiliation:
Lam Research Corporation CMP/Clean Technology 47131 Bayside Parkway Fremont, CA 94538-6517, U.S.A.
Stephen Jew
Affiliation:
Lam Research Corporation CMP/Clean Technology 47131 Bayside Parkway Fremont, CA 94538-6517, U.S.A.
Joseph Li
Affiliation:
Lam Research Corporation CMP/Clean Technology 47131 Bayside Parkway Fremont, CA 94538-6517, U.S.A.
Sri Srivatsan
Affiliation:
Lam Research Corporation CMP/Clean Technology 47131 Bayside Parkway Fremont, CA 94538-6517, U.S.A.
Joseph Simon
Affiliation:
Lam Research Corporation CMP/Clean Technology 47131 Bayside Parkway Fremont, CA 94538-6517, U.S.A.
John M. Boyd
Affiliation:
Lam Research Corporation CMP/Clean Technology 47131 Bayside Parkway Fremont, CA 94538-6517, U.S.A.
KY Ramanujam
Affiliation:
Lam Research Corporation CMP/Clean Technology 47131 Bayside Parkway Fremont, CA 94538-6517, U.S.A.
Rodney Kistler
Affiliation:
Lam Research Corporation CMP/Clean Technology 47131 Bayside Parkway Fremont, CA 94538-6517, U.S.A.
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Abstract

It was found in a Cu-CMP process using EP-C 5001 slurry and IC 1000 pad that Cu removal rate, being extremely low without H2O2 in the slurry, increases up to a maximum with the addition of H2O2, and then decreases again. Analysis of polarization curves and Eh-pH diagrams shows that without H2O2 Cu has the lowest electric potential, as a result, the highest thermodynamic stability in the Cu/slurry system. Addition of H2O2 shifts the potential up and induces the formation of Cu2O, resulting in a high removal rate. At high H2O2 concentration, a CuO passivation film is formed. In this case, only mechanical removal of the passivating oxide film allows the process to proceed. It is speculated that the moving pad surface adheres the oxidized species via the formation of hydrogen bonds with oxygen atoms of copper oxide molecules, thus detaching them from the wafer surface. Each oxygen atom is capable of pulling out two Cu atoms if Cu2O is formed on the surface and only one Cu atom if CuO is formed. This would explain why the removal rate is high at low H2O2 concentration and low at high H2O2 concentration.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 671: Symposium M – Chemical-Mechanical Polishing 2001–Advances and Future Challenges , 2001 , M3.3
Copyright
Copyright © Materials Research Society 2001

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References

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