Interfacial reactions in Cu/Ga and Cu/Ga/Cu couples

Shih-kang Lin, Cheng Liang Cho, Hao Miao Chang

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Cu-to-Cu bonding to connect through-silicon vias in three-dimensional integrated-circuit packaging is the most important interconnection technology in the next-generation semiconductor industry. Soldering is an economic and fast process in comparison with diffusion bonding methods. Ga has high solubility of up to 20 at.% in the Cu-rich face-centered cubic (FCC) phase and high mobility at moderate temperatures. In this work, an attempt has been made to evaluate Ga-based Cu-to-Cu interconnection by transient liquid-phase (TLP) bonding. The Cu/Ga interfacial reactions at temperatures ranging from 160 C to 300 C were examined. For reactions at temperatures lower than 240 C, the reaction path is Cu/γ 3-Cu9Ga4/θ-CuGa 2/liquid, where the γ 3-Cu9Ga4 and θ-CuGa2 phases are thin planar and thick scalloped layers, respectively, while for the reactions at 280 C and 300 C, the scalloped γ 3-Cu9Ga4 phase is the only reaction product. The phase transformation kinetics, reaction mechanisms, and microstructural evolution in the Cu/Ga couples are elaborated. In addition, reactions of Cu/Ga/Cu sandwich couples at 160 C were investigated. The original Cu/liquid/Cu couples isothermally transformed to Cu/γ 3-Cu 9Ga4/ θ-CuGa23-Cu9Ga4/Cu couples as the reaction progressed. However, cracks were observed in the θ-CuGa2 phase regions after metallographic processing. The brittle θ-CuGa2 phase is undesirable for Ga-based TLP bonding.

Original languageEnglish
Pages (from-to)204-211
Number of pages8
JournalJournal of Electronic Materials
Volume43
Issue number1
DOIs
Publication statusPublished - 2014 Jan 1

Fingerprint

Surface chemistry
Liquids
Diffusion bonding
Addition reactions
Microstructural evolution
Soldering
liquid phases
Silicon
Reaction products
Temperature
diffusion welding
Packaging
soldering
Solubility
Phase transitions
Semiconductor materials
liquids
Cracks
packaging
reaction products

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry

Cite this

Lin, Shih-kang ; Cho, Cheng Liang ; Chang, Hao Miao. / Interfacial reactions in Cu/Ga and Cu/Ga/Cu couples. In: Journal of Electronic Materials. 2014 ; Vol. 43, No. 1. pp. 204-211.
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Interfacial reactions in Cu/Ga and Cu/Ga/Cu couples. / Lin, Shih-kang; Cho, Cheng Liang; Chang, Hao Miao.

In: Journal of Electronic Materials, Vol. 43, No. 1, 01.01.2014, p. 204-211.

Research output: Contribution to journalArticle

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