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Buckling instabilities of thin cap layers deposited onto low-k dielectric films

Published online by Cambridge University Press:  11 February 2011

F. Iacopi
Affiliation:
IMEC, Kapeldreef 75, B-3001 Leuven, Belgium E.E. Dept., Katholieke Universiteit Leuven, Belgium
S.H. Brongersma
Affiliation:
IMEC, Kapeldreef 75, B-3001 Leuven, Belgium
T.J. Abell
Affiliation:
affiliated researcher at IMEC from Intel Corp., Santa Clara, CA.
K. Maex
Affiliation:
IMEC, Kapeldreef 75, B-3001 Leuven, Belgium E.E. Dept., Katholieke Universiteit Leuven, Belgium
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Abstract

Compressive stresses in thin capping films deposited onto low-k dielectric substrates are particularly prone to relaxation through buckling. This is due to insufficient cap/low-k film adhesion energy and to the compliance of low dielectric constant films. Low-k dielectric films, especially when porous, have low elastic modulus and demonstrate poor adhesion to other layers.

When adhesion is poor the cap film can locally buckle as if unconstrained. The buckle front can propagate like a crack and lead to complete delamination of the cap layer. If the cap/low-k film adhesive energy is high, wrinkling instabilities can take place under specific conditions determined by the geometry and the mechanical properties of the stack. In this case the dielectric also deforms due to stress relaxation. A theoretical and experimental evaluation of the parameters influencing the occurrence of these instabilities is presented. This study was carried out to explore the application and reliability of low-k materials as dielectrics for advanced interconnects.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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References

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