Effect of copper seed aging on electroplating-induced defects in copper interconnects

Daniele Contestable-Gilkes, Deepak Ramappa, Minseok Oh, Sailesh M. Merchant

Research output: Contribution to journalArticlepeer-review

Abstract

Voids in copper thin films, observed after electroplating, have been linked to seed aging that occurs when a wafer is exposed, over time, to clean-room ambient. Oxidation of the copper seed surface prevents wetting during subsequent copper electroplating, leading to voids. Several surface treatments were employed to counteract the seed aging effect, including reduction of the copper oxide film by hydrogen, reverse plating of the copper surface, and rinsing the wafer surface with electrolyte. Each treatment was applied to wafers increasingly aged from 2 to 14 days, just prior to electroplating. Results showed a significant decrease in postelectroplating defects with all three treatments. The reduction of copper oxide by hydrogen exhibited the most marked results. An increase in surface wetting is shown by a decrease in contact angle measurements and an increase in film reflectivity for treated versus untreated copper wafers. This study shows that, although the copper surface exhibits strong aging effects over a short period of time, using proper surface treatments can eliminate such effects and voids.

Original languageEnglish (US)
Article number41
Pages (from-to)1047-1051
Number of pages5
JournalJournal of Electronic Materials
Volume31
DOIs
StatePublished - Jan 1 2002
Externally publishedYes

Keywords

  • Copper thin films
  • Defects
  • Electroplating
  • Interconnects
  • Seed aging
  • Surface treatment
  • Wetting behavior

ASJC Scopus subject areas

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

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