Effect of contact angle between retaining ring and polishing pad on material removal uniformity in CMP process

  • Yeongbong Park
  • Hyunseop Lee
  • Youngkyun Lee
  • Sunjoon Park
  • Haedo JeongEmail author


This paper presents the effect of the contact angle between the retaining ring and the polishing pad in chemical mechanical polishing (CMP) on the profile of the material removal rate (MRR) around the wafer edge and on the within-wafer nonuniformity (WIWNU). This study demonstrates that the mechanical interaction among the polishing pad, wafer, and retaining ring influences the ability to achieve planarization from the CMP process. In particular, the purpose of this study is to understand the effect of the contact conditions between the retaining ring and the pad on the CMP process. In order to verify the mechanical aspects of the MRR near the wafer edge, retaining rings with different contact angles were prepared. Finite element analysis (FEA) verified the effect of the contact angle between the retaining ring and the polishing pad on the stress distribution around the edge of the wafer. The results of the analysis were corroborated by conducting CMP experiments with 200-mm blanket oxide wafers. As expected, the FEA results were in good agreement with the MRR profile around the edge area. Through simulations and experiments, we concluded that the contact angle is an important factor to achieve a flatter edge profile and the material removal profile around the edge of the wafer was optimum at a 0o contact angle. In particular the WIWNU was below 4% when a flat retaining ring was used. The results of this study make it possible to improve the yield of chip production by ensuring the retaining ring maintains perfect flatness without making any special design changes to the CMP equipment.


CMP Edge exclusion Edge effect Retaining ring Contact angle Finite element analysis 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Thy, T., William, R., Jason, T., Igor, J., Nicholas, C., Paul, J., Reuben, F., Dan, M., Cort, D., Mark, R., Christian, W., Michael, B., Aaron, B., and Thomas, T., “Extreme Edge Engineering — 2 mm Edge Exclusion Challenges and Cost-Effective Solutions for Yield Enhancement in High Volume Manufacturing for 200 mm and 300 mm Wafer Fabs,” IEEE/SEMI Advanced Semiconductor Manufacturing Conference, pp. 453–460, 2004.Google Scholar
  2. 2.
    Yavas, O., Richter, E., Kluthe, C., and Sickmoeller, M., “Wafer-edge yield engineering in leading-edge DRAM manufacturing,” Semiconductor Fabtech., Vol. 39, pp. 1–5, 2009.Google Scholar
  3. 3.
    International Technology Roadmap for Semiconductors, “ITRS Reports 2011 edition,”
  4. 4.
    Baker, A. R., “The origin of the edge effect in chemical mechanical planarization,” Proc. of Electrochem. Soc. Fall Meeting, USA, Vol. 96–22, pp. 228–238, 1996.Google Scholar
  5. 5.
    Nishi, Y. and Doering, R., “Handbook of semiconductor manufacturing technology,” Taylor & Francis, pp. 17–1, 2007.Google Scholar
  6. 6.
    Park, B., Lee, H., Kim, Y., Kim, H., and Jeong, H., “Effect of process parameters on friction force and material removal in oxide chemical mechanical polishing,” Japanese Journal of Applied Physics, Vol. 47, No. 12, pp. 8771–8778, 2008.CrossRefGoogle Scholar
  7. 7.
    Moussa, R. and Quartapella, C., “Next-Generation Materials for CMP Retaining Rings,” VMIC Conference, pp. 501–505, 2003.Google Scholar
  8. 8.
    Touzov, M. M., Fujita, T., and Doy, T. K., “Novel retaining ring to reduce CMP edge exclusion,” IEEE international Semiconductor Manufacturing Symposium, pp. 337–340, 2001.Google Scholar
  9. 9.
    Lee, H., Park, B., Seo, H., Jung, J., Jeong, S., and Jeong, H., “A Study on Frictional Characteristics and Polishing Results of SiO2 Slurry in CMP,” Transactions of the Korean Society of Mechanical Engineers — A, Vol. 29, No. 7, pp. 983–989, 2005.CrossRefGoogle Scholar
  10. 10.
    Lee, H. and Jeong, H., “A Wafer-scale material removal rate profile model for copper chemical mechanical planarization,” International Journal of Machine Tools and Manufacture, Vol. 51, No. 5, pp. 395–403, 2001.CrossRefGoogle Scholar
  11. 11.
    Lin, Y. Y. and Lo, S. P., “A Study on the stress and nonuniformity of the wafer surface for the chemical-mechanical polishing process,” International Journal of Advanced Manufacturing Technology, Vol. 22, No. 5–6, pp. 401–409, 2003.CrossRefGoogle Scholar
  12. 12.
    Kim, H. J., Kim. H. Y., Jeong, H. D., Lee, E. S., and Shin, Y. J., “Friction and thermal phenomena in chemical mechanical polishing,” Journal of Materials Processing Technology, Vol. 130–131, No. 0, pp. 334–338, 2002.CrossRefGoogle Scholar
  13. 13.
    Kwon, D., Kim, H., and Jeong, H., “Heat and its effects to chemical mechanical polishing,” Journal of Materials Processing Technology, Vol. 178, No. 1–3, pp. 82–87, 2006.CrossRefGoogle Scholar
  14. 14.
    Park, B., Jeong, S., Lee, H., Kim, H., Jeong, H., and Dornfelt, D. A., “Experimental investigation of material removal characteristics in silicon chemical mechanical polishing,” Japanese Journal of Applied Physics, Vol. 48, No. 11, pp. 116505, 2009.CrossRefGoogle Scholar
  15. 15.
    Park, J., Jeong, H., Yoshida, K., and Kinoshita, M., “Pad surface treatment to control performance of chemical mechanical planarization,” Japanese Journal of Applied Physics, Vol. 47, No. 2, pp. 1028–1033, 2008.CrossRefGoogle Scholar

Copyright information

© Korean Society for Precision Engineering and Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Yeongbong Park
    • 1
  • Hyunseop Lee
    • 1
  • Youngkyun Lee
    • 1
  • Sunjoon Park
    • 1
  • Haedo Jeong
    • 1
    Email author
  1. 1.Graduate School of Mechanical EngineeringPusan National UniversityBusanSouth Korea

Personalised recommendations