Unidirectional growth of microbumps on (111)-oriented and nanotwinned copper

Hsiang Yao Hsiao, Chien Min Liu, Han Wen Lin, Tao Chi Liu, Chia Ling Lu, Yi Sa Huang, Chih Chen*, King-Ning Tu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

250 Scopus citations


Highly oriented [111] Cu grains with densely packed nanotwins have been fabricated by direct-current electroplating with a high stirring rate. The [111]-oriented and nanotwinned Cu (nt-Cu) allow for the unidirectional growth of Cu6Sn5 intermetallics in the microbumps of three-dimensional integrated-circuit packaging; a uniform microstructure in a large number of microbumps of controlled orientation can be obtained. The high-density twin boundaries in the nt-Cu serve as vacancy sinks during the solid-state reaction between Pb-free solder and Cu and greatly reduce the formation of Kirkendall (or Frenkel) voids.

Original languageEnglish
Pages (from-to)1007-1010
Number of pages4
Issue number6084
StatePublished - 25 May 2012


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