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Effects of bonding pressure on quality of SLID interconnects

 
: Panchenko, I.; Grafe, J.; Mueller, M.; Wolter, K.-J.

:

Beyne, Eric (General Chair) ; IEEE Components, Packaging, and Manufacturing Technology Society; Institute of Electrical and Electronics Engineers -IEEE-:
4th Electronic System-Integration Technology Conference, ESTC 2012 : Amsterdam, Netherlands, 17 - 20 September 2012
New York, NY: IEEE, 2012
ISBN: 978-1-4673-4645-0
7 pp.
Electronics System Integration Technology Conference (ESTC) <4, 2012, Amsterdam>
English
Conference Paper
Fraunhofer IZM ()

Abstract
The investigation of the bonding pressure change on the different quality aspects of the solid-liquid interdiffusion (SLID) interconnects is presented. The stacks were produced by a flux-assisted bonding of two Si dies with an area array of square Cu/SnAg bumps on the bottom die and Cu bumps on the top die at approx. 250 °C. The bonding pressure was varied between 0 MPa, 0.35 MPa, 0.69 MPa, 1.04 MPa, 1.38 MPa, 1.73 MPa, 2.08 MPa, 2.42 MPa. Cross-sections of the stacks were analyzed by optical microscopy and scanning electron microscopy (SEM). Tilt, standoff height (SOH) variation, void fraction, interlayer thickness and Cu3Sn thickness were measured. It will be shown that increase of the bonding pressure can reduce the void fraction from 35.1 % (0 MPa) to 10.7 % (2.42 MPa) and decrease the interlayer thickness at the same time. Decrease of the interlayer thickness is accompanied by solder squeeze and increase of Cu3Sn thickness. Shear tests revealed an average shear str ength of (81.3 ± 21.5) MPa for the produced samples. The analysis of the fracture surfaces with SEM revealed that the weakest interface is located between Cu6Sn5 and Cu3Sn intermetallic compounds (IMCs) close to the initial Cu bump.

: http://publica.fraunhofer.de/documents/N-350316.html