Characterization of nanoscopic Cu/diamond interfaces prepared by surface-activated bonding: Implications for thermal management

Jianbo Liang, Yutaka Ohno, Yuichiro Yamashita, Yasuo Shimizu, Shinji Kanda, Naoto Kamiuchi, Seongwoo Kim, Koyama Koji, Yasuyoshi Nagai, Makoto Kasu, Naoteru Shigekawa

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

The microstructures of Cu/diamond interfaces prepared by surface-activated bonding at room temperature are examined by cross-sectional scanning transmission electron microscopy (STEM). A crystalline defect layer composed of Cu and diamond with a thickness of approximately 4.5 nm is formed at the as-bonded interface, which is introduced by irradiation with an Ar beam during the bonding process. No crystalline defect layer is observed at the 700 °C annealed interface, which is attributed to the recrystallization of the defect layer due to the high-temperature annealing process. Instead of the defect layer, a mating interface layer and a copper oxide layer are formed at the interface. The mating interface layer and the copper oxide layer play a role in relieving the residual stress caused by the difference between the thermal expansion coefficients of diamond and Cu. The thermal boundary resistance (TBR) of the as-bonded interface is measured to be 1.7 ± 0.2 × 10−8 m2·K/W by the time domain pulsed-light-heating thermoreflectance technique. These results indicate that the direct bonding of diamond and Cu is a very effective technique for improving the heat-dissipation performance of power devices.

Original languageEnglish
Pages (from-to)2455-2462
Number of pages8
JournalACS Applied Nano Materials
Volume3
Issue number3
DOIs
Publication statusPublished - 2020

Keywords

  • Cu/diamond direct bonding
  • Interfacial microstructure
  • Thermal boundary resistance
  • Thermal conductivity

ASJC Scopus subject areas

  • Materials Science(all)

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