A Low-Cost Passivation for Low Temperature Cu-Cu Bonding Using PVD-Deposited Cu3N

Tzu Heng Hung, Ping Jung Liu, Chiao Yen Wang, Tsai Fu Chung, Kuan Neng Chen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

PVD-deposited Cu3N has been demonstrated for Cu-Cu bonding as a low-cost passivation material. Cu3N exhibits stability at room temperature but undergoes decomposition upon heating, making it an attractive candidate for Cu bonding passivation. XRD analysis reveals that the decomposition of PVD-deposited Cu3N primarily occurs within the temperature range of 200 ° C∼250° C. Cu3N-Cu3N bonding, relying on the decomposition reaction, is successfully demonstrated, and TEM analysis confirms the presence of Cu grains at the bonding interface. Moreover, Cu bonding using Cu3N passivation has been demonstrated as well. The bonding capability at low temperatures is found to be influenced by the thin film properties of Cu3N. For wafer level bonding, the N_2 flow rate during Cu3N deposition requires careful adjustment to balance the anti-oxidation capability and the N_2 outgassing phenomenon. For chip level bonding, the N_2 outgassing phenomenon poses no significant issue. By demonstrating the potential of Cu3N as a passivation material, this study suggests a promising method for achieving lower temperature requirements in Cu bonding through the adjustment of Cu3N thin film properties.

Original languageEnglish
Pages (from-to)473-479
Number of pages7
JournalIEEE Journal of the Electron Devices Society
Volume11
DOIs
StatePublished - 2023

Keywords

  • Copper nitride
  • Cu bonding
  • PVD-deposited CuN
  • passivation technology

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