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Effects of Bonding Process Parameters on Wafer-to-Wafer Alignment Accuracy in Benzocyclobutene (BCB) Dielectric Wafer Bonding

Published online by Cambridge University Press:  01 February 2011

F. Niklaus
Affiliation:
Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, NY, USA.
R.J. Kumar
Affiliation:
Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, NY, USA.
J.J. McMahon
Affiliation:
Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, NY, USA.
J. Yu
Affiliation:
Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, NY, USA.
T. Matthias
Affiliation:
Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, NY, USA.
M. Wimplinger
Affiliation:
Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, NY, USA.
P. Lindner
Affiliation:
Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, NY, USA.
J.Q. Lu
Affiliation:
Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, NY, USA.
T.S. Cale
Affiliation:
Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, NY, USA.
R.J. Gutmann
Affiliation:
Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, NY, USA.
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Abstract

Wafer-level three-dimensional (3D) integration is an emerging technology to increase the performance and functionality of integrated circuits (ICs). Aligned wafer-to-wafer bonding with dielectric polymer layers (e.g., benzocyclobutene (BCB)) is a promising approach for manufacturing of 3D ICs, with minimum bonding impact on the wafer-to-wafer alignment accuracy essential. In this paper we investigate the effects of thermal and mechanical bonding parameters on the achievable post-bonding wafer-to-wafer alignment accuracy for polymer wafer bonding with 200 mm diameter wafers. Our baseline wafer bonding process with softbaked BCB (∼35% cross-linked) has been modified to use partially cured (∼ 43% crosslinked) BCB. The partially cured BCB layer does not reflow during bonding, minimizing the impact of inhomogeneities in BCB reflow under compression and/or slight shear forces at the bonding interface. As a result, the non-uniformity of the BCB layer thickness after wafer bonding is less than 0.5% of the nominal layer thickness and the wafer shift relative to each other during the wafer bonding process is less than 1 μm (average) for 200 mm diameter wafers. The critical adhesion energy of a bonded wafer pair with the partially cured BCB wafer bonding process is similar to that with soft-baked BCB.

Type
Research Article
Copyright
Copyright © Materials Research Society 2005

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References

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