Location of Repository

Fabrication of wafer-level thermocompression bonding

By C.H. Tsau, S.M. Spearing and M A. Schmidt


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)

Topics: T1
Year: 2002
OAI identifier: oai:eprints.soton.ac.uk:23016
Provided by: e-Prints Soton

Suggested articles



  1. A graphite crucible for spitting-free high rate e-gun evaporation of
  2. (1989). A test specimen for determining the fracture resistance of bimaterial interfaces,”
  3. (1976). Aging properties of gold layers with different adhesion layers,”
  4. (1992). An eutectic bonding technology at a temperaturebelowtheeutecticpoint,”inProc.42ndElectronicComponents and Technology Conference,
  5. (1988). Bonding of silicon wafers for silicon-on-insulator,”
  6. (1992). bonding of very large arrays,” in
  7. (1999). Challenges in the packaging of MEMS,” in
  8. (1975). Effectofsurfacecontamination onthe thermcompression bondability of gold,”
  9. (1993). Effects of temperature, thickness and atmosphere on mixing in Au–Ti bilayer thin films,”
  10. (2001). H.ReichlandV.Grosser,“Overviewanddevelopmenttrendsinthefield of MEMS packaging,” in
  11. (1991). I.E.Reimanis,B.J.Dalgleish,andA.G.Evans,“Thefractureresistance of a model metal/ceramic interface,”
  12. (1975). Low temperature diffusion of Au into Si
  13. (1995). Packaging of microfabricated devices and systems,”
  14. (2000). Plasticity contributions to interface adhesion in thin-film interconnect structures,”
  15. (1993). Silicon pressure sensor using wafer bonding technology,”
  16. (1998). Simultaneous fabrication of dielectric and electrical joints by wafer bonding,”
  17. (1975). The high temperature deformation properties of gold and thermocompression bonding,”
  18. (2000). The indent reflow sealing (IRS)technique—Amethodforthefabricationofsealedcavities for
  19. (1968). The Solid Phase Welding of Metals.
  20. (1995). Thermocompression bonding effects on bump-pad adhesion,”
  21. (1968). Thin Film Technology:D .V a n Nostrand,
  22. (1999). Wafer direct bonding: Tailoring adhesion between brittle materials,”
  23. (2001). Wafer-to-wafer bonding of nonplanarized MEMS surfaces using solder,”

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.