Low-temperature direct copper-to-copper bonding enabled by creep on highly (1 1 1)-oriented Cu surfaces

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

*Corresponding author for this work

Research output: Contribution to journalArticle

45 Scopus citations

Abstract

We achieve low-temperature Cu-to-Cu direct bonding using highly (1 1 1)-orientated Cu films. The bonding temperature can be lowered to 200 C at a stress of 114 psi for 30 min at 10-3 torr. The temperature is lower than the reflow temperature of 250 C for Pb-free solders. Our breakthrough is based on the finding that the Cu (1 1 1) surface diffusivity is the fastest among all the planes of Cu and the bonding process can occur through surface diffusion creep on the (1 1 1) surfaces.

Original languageEnglish
Pages (from-to)65-68
Number of pages4
JournalScripta Materialia
Volume78-79
DOIs
StatePublished - 1 May 2014

Keywords

  • Creep
  • Cu-to-Cu direct bonding
  • Diffusion
  • Preferred orientation

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