Achieving low-temperature wafer level bonding with Cu-Sn-In ternary at 150 °C

Obert Golim, Vesa Vuorinen, Glenn Ross, Tobias Wernicke, Marta Pawlak, Nikhilendu Tiwary, Mervi Paulasto-Kröckel

Research output: Contribution to journalLetterScientificpeer-review

7 Citations (Scopus)
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Abstract

In this work, a low-temperature wafer-level bonding process at 150 °C was carried out on Si wafers containing 10 µm-sized microbumps based on the Cu-Sn-In ternary system. Thermodynamic study shows that addition of In enables low-melting temperature metals to reach liquid phase below In melting point (157 °C) and promotes rapid solidification of the intermetallic layer, which are beneficial for achieving low-temperature bonding. Microstructural observation shows high bonding quality with low amount of defect. SEM and TEM characterization concludes that a single-phase intermetallic formed in the bond and identified as Cu6(Sn,In)5 with a hexagonal lattice. Mechanical tensile test indicates that the bond has a mechanical tensile strength of 30 MPa, which are adequate for 3D heterogeneous integration.
Original languageEnglish
Article number114998
Number of pages3
JournalScripta Materialia
Volume222
Early online date1 Sept 2022
DOIs
Publication statusPublished - 1 Jan 2023
MoE publication typeB1 Non-refereed journal articles

Keywords

  • SLID bonding
  • Micro-bump
  • Solder joint technology
  • Intermetallics
  • Interdiffusion

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