Low-temperature direct copper-to-copper bonding enabled by creep on (111) surfaces of nanotwinned Cu

Direct Cu-to-Cu bonding was achieved at temperatures of 150–250 °C using a compressive stress of 100 psi (0.69 MPa) held for 10–60 min at 10 −3  torr. The key controlling parameter for direct bonding is rapid surface diffusion on (111) surface of Cu. Instead of using (111) oriented single crystal of...

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Published inScientific reports Vol. 5; no. 1; p. 9734
Main Authors Liu, Chien-Min, Lin, Han-Wen, Huang, Yi-Sa, Chu, Yi-Cheng, Chen, Chih, Lyu, Dian-Rong, Chen, Kuan-Neng, Tu, King-Ning
Format Journal Article
LanguageEnglish
Published London Nature Publishing Group UK 12.05.2015
Nature Publishing Group
Subjects
121/143
639/301/1005/1007
639/301/357/995
Copper
Electron microscopy
Grain boundaries
Humanities and Social Sciences
Low temperature
multidisciplinary
Science
Temperature effects
Transmission electron microscopy
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Summary:Direct Cu-to-Cu bonding was achieved at temperatures of 150–250 °C using a compressive stress of 100 psi (0.69 MPa) held for 10–60 min at 10 −3  torr. The key controlling parameter for direct bonding is rapid surface diffusion on (111) surface of Cu. Instead of using (111) oriented single crystal of Cu, oriented (111) texture of extremely high degree, exceeding 90%, was fabricated using the oriented nano-twin Cu. The bonded interface between two (111) surfaces forms a twist-type grain boundary. If the grain boundary has a low angle, it has a hexagonal network of screw dislocations. Such network image was obtained by plan-view transmission electron microscopy. A simple kinetic model of surface creep is presented; and the calculated and measured time of bonding is in reasonable agreement.
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ISSN:2045-2322
2045-2322
DOI:10.1038/srep09734