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


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.



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.


  1. Apone D, Gray C, Rogers C, Manno VP, Barns C, Moinpour M, Anjur S, Philipossian A (2005) Viewing asperity behavior under the wafer during CMP. Mater Res Soc Proc 867:W2.3.1–W2.3.7Google Scholar
  2. Arcoumanis C, McGuirk JJ, Palma JMLM (1990) On the use of fluorescent dyes for concentration measurements in water flows. Exp Fluids 10:177–180CrossRefGoogle Scholar
  3. Bassnett S, Reinisch L, Beebe DC (1990) Intracellular pH measurement using single excitation-dual emission fluorescence ratios. Am J Physiol Cell Physiol 268(1):171–178Google Scholar
  4. Bohren CF, Huffman DR (1998) Absorption and scattering of light by small particles. Wiley, New YorkGoogle Scholar
  5. Chan EY (2003) Instantaneous mapping in chemical mechanical planarization. Master’s thesis, Tufts UniversityGoogle Scholar
  6. Chandrasekhar S (1960) Radiative transfer. Dover Publications, New YorkGoogle Scholar
  7. Cook LM (1990) Chemical processes in glass polishing. J Non-Cryst Solids 120:152–171CrossRefGoogle Scholar
  8. Coppeta J, Rogers C (1998) Dual emission laser induced fluorescence for direct planar scalar behavior measurements. Exp Fluids 26:1–15CrossRefGoogle Scholar
  9. Coppeta J, Rogers C, Philipossian A, Kaufman FB (1996) A technique for measuring slurry-flow dynamics during chemical-mechanical polishing. In: Materials research society proceedings, symposium L, fallGoogle Scholar
  10. Coppeta J, Rogers C, Racz L, Philipossian A, Kaufman FB (2000) Investigating slurry transport beneath a wafer during chemical mechanical polishing process. J Electrochem Soc 147(5):1903–1909CrossRefGoogle Scholar
  11. Cox AJ, DeWeerd AJ, Linden J (2002) An experiment to measure Mie and Rayleigh total scattering cross sections. Am J Phys 70(6):620–625CrossRefGoogle Scholar
  12. Gaigalas AJ, Wang L (2008) Measurement of fluorescent quantum yield using a spectrometer with an integrating sphere detector. J Res Natl Inst Stand Technol 113(1):17–28Google Scholar
  13. Garofalakis A, Zacharakis G, Filippidis G, Sanidas E, Tsiftsis D, Ntziachristos V, Papazoglou T, Ripoll J (2004) Characterization of the reduced scattering coefficient for optically thin samples: theory and experiments. J Opt A Pure Appl Opt 6:726–735CrossRefGoogle Scholar
  14. Gray C (2005) Measurement of pad compression during chemical mechanical polishing. Master’s thesis, Tufts UniversityGoogle Scholar
  15. Gray C (2008) Detecting pad-wafer contact in CMP using dual emission laser induced fluorescence. Ph. D. Thesis, Tufts UniversityGoogle Scholar
  16. Gray C, Apone D, Rogers C, Manno VP, Barns C, Moinpour M, Anjur S, Philipossian A (2005) Viewing asperity behavior under the wafer during CMP. Electrochem Solid State Lett 8:G109–G111CrossRefGoogle Scholar
  17. Harris DC (1989) Symmetry and spectroscopy: an introduction to vibrational and electronic spectroscopy. Dover Publications, MineolaGoogle Scholar
  18. Hecht E (2002) Optics 4th edn. Pearson Addison Wesley, San FranciscoGoogle Scholar
  19. Hidrovo CH, Hart DP (2001) Emission reabsorption laser induced fluorescence (ERLIF) film thickness measurement. Meas Sci Technol 12:467–477CrossRefGoogle Scholar
  20. Hidrovo CH, Brau RR, Hart DP (2004) Excitation nonlinearities in emission reabsorption laser-induced fluorescence. App Opt 43(4):894–913CrossRefGoogle Scholar
  21. Li Z, Lee H, Borucki L, Rogers C, Kikuma R, Rikita N, Nagasawa K, Philipossian A (2006) Effects of disk design and kinematics of conditioners on process hydrodynamics during copper CMP. J Electrochem Soc 153(5):G399–G404CrossRefGoogle Scholar
  22. Lu J, Coppeta J, Rogers C, Racz L, Philipossian A, Kaufman FB (2000) The effect of wafer shape on slurry film thickness and friction correlation in chemical mechanical planarization. Mater Res Soc Proc 613:E1.2Google Scholar
  23. McQuarrie DA, Simon JD (1997) Physical chemistry: a molecular approach, chap. 15. University Science Books, p 626Google Scholar
  24. Muldowney GP (2007) Advances in understanding and control of CMP performance: contact-hydrodynamics at wafer, groove and asperity scale. Mater Res Soc Symp Proc 991:153–164Google Scholar
  25. Nishioka T, Sekine K, Tateyama Y (1999) Modeling on hydrodynamic effects of pad surface roughness in CMP process, interconnect technology 1999. In: IEEE international conference, pp 89–91, May 1999Google Scholar
  26. Rogers C, Coppeta J, Racz L, Philipossian A, Kaufman FB, Bramono D (1998) Analysis of flow between a wafer and pad during CMP processes. J Electron Mater 27(10):1082–1087CrossRefGoogle Scholar
  27. Sakakibara J, Adrian RJ (1999) Whole field measurement of temperature in water using two-color laser induced fluorescence. Exp Fluids 26:7–15CrossRefGoogle Scholar
  28. Sakakibara J, Adrian RJ (2004) Measurement of temperature field of a rayleigh-benard convection using two-color laser-induced fluorescence. Exp Fluids 37:331–340CrossRefGoogle Scholar
  29. Shlien DJ (1998) Instantaneous concentration field measurement technique from flow visualization photographs. Exp Fluids 6:541–546Google Scholar
  30. Strömberg N, Hulth S (2005) Assessing an imaging ammonium sensor using time correlated pixel-by-pixel calibration. Analytical Chemica Acta 550:61–68CrossRefGoogle Scholar

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

Personalised recommendations