Microstructure control of unidirectional growth of η-Cu 6Sn5 in microbumps on 〈1 1 1〉 oriented and nanotwinned Cu

Han Wen Lin, Chia Ling Lu, Chien Min Liu, Chih Chen*, Delphic Chen, Jui Chao Kuo, King-Ning Tu

*Corresponding author for this work

Research output: Contribution to journalArticle

26 Scopus citations

Abstract

Anisotropic microstructure is becoming a critical issue in microbumps used in 3-D integrated circuit packaging. We report here an experimental approach for controlling the microstructure of η-Cu6Sn5 intermetallic compound in microbumps by using 〈1 1 1〉 oriented and nanotwinned Cu pads as the under-bump-metallization. By electroplating arrays of large numbers of 〈1 1 1〉 oriented and nanotwinned Cu pads and by electroplating the Sn2.3Ag solder on the pads, we form η-Cu 6Sn5 in the reflow at 260 C for 1 min. The η-Cu 6Sn5 showed a highly preferential growth along the 〈0 0 0 1〉 direction. As reflow time is extended, the preferred texture of η-Cu6Sn5 changed to {21̄1̄3}. The results indicate that we can control the uniform microstructure of η-Cu 6Sn5 intermetallic by controlling the microstructure of the Cu under-bump-metallization.

Original languageEnglish
Pages (from-to)4910-4919
Number of pages10
JournalActa Materialia
Volume61
Issue number13
DOIs
StatePublished - 1 Aug 2013

Keywords

  • Copper
  • Intermetallic compounds
  • Soldering

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