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Fabrication of wafer-level thermocompression bonding

Fabrication of wafer-level thermocompression bonding
Fabrication of wafer-level thermocompression bonding
Thermocompression bonding of gold is a promising technique for achieving low temperature, wafer-level bonding. The fabrication process for wafer bonding at 300/spl deg/C via compressing gold under 7 MPa of pressure is described in detail. One of the issues encountered in the process development was e-beam source spitting, which resulted in micrometer diameter sized Au on the surfaces, and made bonding difficult. The problem was solved by inserting a tungsten liner to the graphite crucible. Surface segregation of Si on the Au surface at the bonding temperature was observed. Using Auger spectroscopy, a 1500 /spl Aring/ SiO/sub 2/ barrier layer was shown to be sufficient in preventing Si from reaching the surface. Lastly, a four-point bend delamination technique was used to quantify the bond toughness. The associated process steps that were required to prepare the test specimens are described. The critical strain energy release rate for the bonds ranged between 22 to 67 J/m/sup 2/ and was not shown to be strongly associated with the gold bond layer thickness in the thickness range studied (0.23 to 1.4 /spl mu/m).
1057-7157
641-647
Tsau, C.H.
fedc90fd-54f5-417a-8b6e-2447a63b6e87
Spearing, S.M.
9e56a7b3-e0e8-47b1-a6b4-db676ed3c17a
Schmidt, M A.
96737d64-1e2c-44a3-b629-a9134c56eefa
Tsau, C.H.
fedc90fd-54f5-417a-8b6e-2447a63b6e87
Spearing, S.M.
9e56a7b3-e0e8-47b1-a6b4-db676ed3c17a
Schmidt, M A.
96737d64-1e2c-44a3-b629-a9134c56eefa

Tsau, C.H., Spearing, S.M. and Schmidt, M A. (2002) Fabrication of wafer-level thermocompression bonding. Journal of Microelectromechanical Systems, 11 (6), 641-647. (doi:10.1109/JMEMS.2002.805214).

Record type: Article

Abstract

Thermocompression bonding of gold is a promising technique for achieving low temperature, wafer-level bonding. The fabrication process for wafer bonding at 300/spl deg/C via compressing gold under 7 MPa of pressure is described in detail. One of the issues encountered in the process development was e-beam source spitting, which resulted in micrometer diameter sized Au on the surfaces, and made bonding difficult. The problem was solved by inserting a tungsten liner to the graphite crucible. Surface segregation of Si on the Au surface at the bonding temperature was observed. Using Auger spectroscopy, a 1500 /spl Aring/ SiO/sub 2/ barrier layer was shown to be sufficient in preventing Si from reaching the surface. Lastly, a four-point bend delamination technique was used to quantify the bond toughness. The associated process steps that were required to prepare the test specimens are described. The critical strain energy release rate for the bonds ranged between 22 to 67 J/m/sup 2/ and was not shown to be strongly associated with the gold bond layer thickness in the thickness range studied (0.23 to 1.4 /spl mu/m).

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Published date: 2002

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Local EPrints ID: 23016
URI: http://eprints.soton.ac.uk/id/eprint/23016
ISSN: 1057-7157
PURE UUID: 49082c3b-a04c-45b5-af9b-5e1cfd3a1bf0
ORCID for S.M. Spearing: ORCID iD orcid.org/0000-0002-3059-2014

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Date deposited: 10 Mar 2006
Last modified: 17 Dec 2019 01:48

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Contributors

Author: C.H. Tsau
Author: S.M. Spearing ORCID iD
Author: M A. Schmidt

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