Electromigration Reliability of Cu3Sn Microbumps for 3D Heterogeneous Integration

Nikhilendu Tiwary, Christian Grosse, Michael Kögel, Thilo Windemuth, Glenn Ross, Vesa Vuorinen, Sebastian Brand, Mervi Paulasto-Kröckel

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

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Abstract

3D heterogeneous integration (HI) and advanced packaging (AP) technologies require small volume, high-density interconnects for stacking discrete chips for which the reliability of interconnects becomes crucial. Intermetallic compounds (IMCs) based μbumps have been shown to outperform solder-based μbumps concerning their resistance to electromigration (EM) related failures, which is a key index to assess the interconnect reliability. Cu-Sn solid-liquid interdiffusion (SLID) bonding is an attractive low-cost wafer-level bonding technology for rapid manufacturing of full Cu3Sn IMC μbumps, However, SLID requires melting of Sn during the bonding process which poses risks and design challenges in manufacturing. Due to Sn squeeze-out during the bonding process, Sn melt could react with redistribution layers (RDLs) or metallization layers and form IMCs at undesired locations resulting in early failures thereby compromising the reliability. The Sn-squeeze out issue during bonding is addressed in this work by designing test structures with equal and unequal lateral dimensions of μbumps in the top and bottom wafers. The effects of Sn-squeeze out on the EM resistance and reliability are compared in both designs. Significant improvement in the Sn-squeeze out and corresponding EM resistance was observed in the test structures manufactured with unequal lateral dimensions of μbumps in the top and bottom wafers. FE element simulations were carried out to gain insights and assess the impact of Sn squeeze-out on the reliability and functionality of the Cu3Sn μbumps.

Original languageEnglish
Title of host publication2024 IEEE 10th Electronics System-Integration Technology Conference, ESTC 2024 - Proceedings
PublisherIEEE
Number of pages7
ISBN (Electronic)979-8-3503-9036-0
DOIs
Publication statusPublished - 2024
MoE publication typeA4 Conference publication
EventElectronics System-Integration Technology Conference - Berlin, Germany
Duration: 11 Sept 202413 Sept 2024

Publication series

Name Electronics System-Integration Technology Conference
ISSN (Electronic)2687-9727

Conference

ConferenceElectronics System-Integration Technology Conference
Abbreviated titleESTC
Country/TerritoryGermany
CityBerlin
Period11/09/202413/09/2024

Keywords

  • Cu-Sn SLID bonding
  • electromigration
  • failure analysis
  • FE simulations
  • heterogeneous integration

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