Correlation between the microstructures of bonding interfaces and the shear strength of Cu-to-Cu joints using (111)-oriented and nanotwinned Cu

Jing Ye Juang, Chia Ling Lu, Yu Jin Li, King-Ning Tu, Chih Chen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Highly (111)-oriented Cu pillar-bumps were bonded to highly (111)-oriented Cu films at temperatures ranging from 200 °C/100 °C to 350 °C/100 °C in N2 ambient conditions. The microstructures of the bonded interfaces affected the shear strength performance of the bonded Cu joints. The bonded interfaces at 300 °C/100 °C and 350 °C/100 °C had far fewer voids than interfaces bonded at 200 °C/100 °C and 250 °C/100 °C. In addition, grain growth took place across the bonding interfaces at temperatures above 300 °C/100 °C. The corresponding orientation map (OIM) showed the preferred orientation of large grown grains to be < 100 >. Shear tests revealed that the fracture mode was brittle for joints bonded at 200 °C/100 °C, but became ductile after bonded above 300 °C/100 °C. Based on the results, we found that voids and grain growth behavior play import roles in the shear strength performance of bonded Cu joints.

Original languageEnglish
Article number2368
Number of pages7
JournalMaterials
Volume11
Issue number12
DOIs
StatePublished - Dec 2018

Keywords

  • Cu-to-Cu direct bonding
  • Grain growth
  • Nanotwinned Cu
  • Shear strength
  • Surface diffusion

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