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

Chien Min Liu, Han Wen Lin, Yi Sa Huang, Yi Cheng Chu, Chih Chen*, Dian Rong Lyu, Kuan-Neng Chen, King-Ning Tu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

61 Scopus citations

Abstract

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.

Original languageEnglish
Article number9734
JournalScientific reports
Volume5
DOIs
StatePublished - 12 May 2015

Fingerprint Dive into the research topics of 'Low-temperature direct copper-to-copper bonding enabled by creep on (111) surfaces of nanotwinned Cu'. Together they form a unique fingerprint.

Cite this