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Stress gradients observed in Cu thin films induced by capping layers

Published online by Cambridge University Press:  31 January 2011

Conal E. Murray ,
Paul R. Besser ,
Christian Witt  and
Jean L. Jordan-Sweet
Conal E. Murray*
Affiliation:
IBM T.J. Watson Research Center, Yorktown Heights, New York 10598
Paul R. Besser*
Affiliation:
Advanced Micro Devices, Sunnyvale, California 94088
Christian Witt
Affiliation:
GlobalFoundries, T.J. Watson Research Center, Yorktown Heights, New York 10598
Jean L. Jordan-Sweet
Affiliation:
IBM T.J. Watson Research Center, Yorktown Heights, New York 10598
*
a)Address all correspondence to this author. e-mail: conal@us.ibm.com
b)Present address: Unity Semiconductor, Sunnyvale, CA.
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Abstract

Glancing-incidence x-ray diffraction (GIXRD) has been applied to the investigation of depth-dependent stress distributions within electroplated Cu films due to overlying capping layers. Cu films, 0.65 μm thick, plated on conventional barrier and seed layers received a chemical vapor deposited (CVD) SiCxNyHz cap, an electrolessly deposited CoWP layer, or a CoWP layer followed by a SiCxNyHz cap. GIXRD and conventional x-ray diffraction measurements revealed that strain gradients were created in Cu films possessing a SiCxNyHz cap, where a greater in-plane tensile stress of approximately 180 MPa was generated near the film/cap interface as a result of constraint imposed by the SiCxNyHz layer during cooling from the cap deposition temperature. Although Cu films possessing a CoWP cap without a SiCxNyHz layer did not exhibit depth-dependent stress distributions, subsequent annealing introduced stress gradients and increased the bulk Cu stress. However, a thermal excursion to liquid-nitrogen temperatures significantly reduced tensile stresses in the Cu films.

Keywords

Thermal stressesX-ray diffraction (XRD)Cu
Type
Outstanding Symposium Papers
Information
Journal of Materials Research , Volume 25 , Issue 4 , April 2010 , pp. 622 - 628
Copyright
Copyright © Materials Research Society 2010

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