Inhibition of alumina deposition during tungsten chemical mechanical planarization through the use of citric acid

L. Zhang, S. Raghavan, S. Meikle, G. Hudson

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

The beneficial effects of citric acid in inhibiting alumina particle deposition onto silica areas during tungsten chemical mechanical planarization were investigated. The electrokinetics of alumina in the presence of citric acid and the uptake of citric acid by alumina were studied experimentally. At a pH of 4, as the citric acid concentration was increased, the zeta potential of alumina became less positive and reversed sign. Slurry dip tests and small-scale polishing experiments were carried out and the surface cleanliness of contaminated oxide surfaces was characterized with a field emission scanning electron microscope and image analysis. It has been demonstrated that citric acid is very effective in controlling alumina contamination on oxide surfaces when added into the slurry. Electrochemical tests showed that citric acid does not significantly attack tungsten films. A mechanism for the interaction between citric acid and alumina particles has been proposed.

Original languageEnglish (US)
Pages (from-to)1442-1447
Number of pages6
JournalJournal of the Electrochemical Society
Volume146
Issue number4
DOIs
StatePublished - Apr 1 1999

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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