Analysis of flow between a wafer and pad during CMP processes

C. Rogers, J. Coppeta, L. Racz, A. Philipossian, F. B. Kaufman, D. Bramono

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

In this paper, we summarize the development of a numerical model for the chemical mechanical planarization (CMP) process and experimentally investigate the effects of pad conditioning on slurry transport and mixing. A simplified two-dimensional numerical model of slurry flow beneath a stationary wafer was developed to determine the pressure and shear stress beneath a wafer. The initial results indicate that in the hydrodynamic regime a positive upward pressure is exerted on the wafer. We also examined three cases to study pad effects on slurry transport; polishing with an Embossed Politex pad, an unconditioned IC1000 pad, and a conditioned IC1000 pad. Cab-O-Sperse SC1 slurry was used in a 1:1.5 dilution with water. Mixing data show that conditioning has a negligible effect on the rate of slurry entrainment and mixing; however, conditioning has a large effect on the thickness of the slurry layer between the wafer and pad. Conditioning was found to increase the slurry thickness by a factor of two. In addition the gradients in slurry age beneath the wafer were compared among the three cases. The IC1000 pads supported a gradient in the inner third of the wafer only, while the Embossed Politex pad showed a linear gradient across the wafer implying it retains pockets of unmixed slurry in the embossed topography.

Original languageEnglish (US)
Pages (from-to)1082-1087
Number of pages6
JournalJournal of Electronic Materials
Volume27
Issue number10
DOIs
StatePublished - Oct 1998
Externally publishedYes

Keywords

  • CMP numerical simulation
  • Chemical mechanical planarization (CMP)
  • Chemical mechanical polishing
  • Dual emission laser induced fluorescence

ASJC Scopus subject areas

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

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