Investigation of bonding mechanism for low-temperature Cu–Cu bonding with passivation layer

Zhong Jie Hong, Demin Liu, Han Wen Hu, Chih I. Cho, Ming Wei Weng, Jui Han Liu, Kuan Neng Chen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

The bonding mechanism of low-temperature Cu–Cu thermal compression bonding (TCB) with passivation layer has been investigated in this research. After the structures of Cu with Au passivation and Cu with Pd passivation were bonded at 180 °C, the analyses of transmission electron microscope (TEM) were performed for the bonded structures to explore the bonding behavior of passivated-Cu during different stages of the TCB process. The results indicate that grain boundary diffusion of Cu leads to formation of amorphous Cu at the bonding interface in the passivated-Cu structure. Furthermore, diffusion of Cu atoms and recrystallization of amorphous Cu into polycrystalline Cu can eliminate voids at the bonding interface during the TCB process. Comparing to conventional Cu direct bonding with high crystallinity Cu at the bonding interface, passivated-Cu bonding can be achieved by much lower energy, leading to high quality bonding results with low thermal budget.

Original languageEnglish
Article number153243
JournalApplied Surface Science
Volume592
DOIs
StatePublished - 1 Aug 2022

Keywords

  • 3DIC
  • Bonding mechanism
  • Cu bonding
  • Low temperature bonding
  • Metal bonding

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