Experiments in Fluids

, Volume 51, Issue 1, pp 281–293 | Cite as

Modeling of dual emission laser induced fluorescence for slurry thickness measurements in chemical mechanical polishing

  • Caprice Gray
  • Chris B. Rogers
  • Vincent P. Manno
  • Robert D. White
Research Article

Abstract

Dual emission laser induced fluorescence (DELIF) is a technique for measuring the instantaneous thin fluid film thickness in dynamic systems. Two fluorophores within the system produce laser induced emissions that are filtered and captured by two cameras. The ratio of the images from these cameras is used to cancel the effect of the laser beam profile on the image intensity. The resultant intensity ratio can be calibrated to a fluid film thickness. The utilization of a 2-dye system when applied to Chemical Mechanical Polishing (CMP) is complicated by the fluorescence of the polymeric polishing pad and the light scattering particles in the polishing slurry. We have developed a model of DELIF for CMP with 1-dye employing the polishing pad as the second fluorophore. While scattering particles in the slurry decrease the overall intensity of the individual images, the contrast in the image ratio increases. Using the 1-dye DELIF system to measure thin slurry films, our model results indicate that a cubic calibration may be needed. However, experimental results suggest a linear calibration is achieved for slurry films between 0 and 133 μm thick with scattering coefficients as high as 8.66 mm−1 at a wavelength equal to 410 nm.

Notes

Acknowledgments

This project would not have been possible without the support of our funders: Intel Corporation, Cabot Microelectronics, and the NSF/SRC ERC with the University of Arizona. Many technical representatives from these organizations have provided input for this research. These representatives include Sriram Anjur from Cabot Microelectrons; Chris Barns formerly of Intel Corporation and presently from Cabot Microelectronics; Mansour Moinpour and Don Hooper from Intel Corporation; Professor Ara Philipossian from the University of Arizona; and Dr. Len Borucki, from Araca Corporation.

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Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Caprice Gray
    • 1
  • Chris B. Rogers
    • 1
  • Vincent P. Manno
    • 1
  • Robert D. White
    • 1
  1. 1.Tufts UniversityMedfordUSA

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