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Journal of Applied Electrochemistry

, Volume 39, Issue 10, pp 1719–1724 | Cite as

An investigation of phosphate based ECMP electrolyte performance on feature scale planarization

  • Kristin G. Shattuck
  • Alan C. West
Original Paper

Abstract

Conventional copper chemical mechanical planarization (CMP) techniques are being pushed to their limits by increasing industrial standards caused by device miniaturization and the use of new materials. There is a need to investigate alternative methods of polishing to maintain and/or improve planarization standards while operating at low downforce. In this study, electrochemical mechanical planarization (ECMP) is considered as an alternative and/or an extension to current CMP processes. ECMP is unique due to the combination of an applied voltage to oxidize Cu and an abrasion from a polishing pad, which potentially allows the system to achieve high levels of planarization through the use of an appropriately tailored electrolyte. An electrolyte containing 1.0 M potassium phosphate salt concentration with a pH value of 2 and a benzotriazole (BTA) concentration of 0.001 M was tested for its planarization capability on patterned Cu structures using a custom built ECMP tool. Feature sizes of the Cu structures were varied from 1 to 6 μm. Similar planarization results were achieved using three pad types. All experiments were performed at 0.5 V versus Ag/AgCl reference. The average step height reduction (SHR) was ~840 nm while the decrease in the average metal thickness removed (λavg) was on the order of ~430 nm. Because features were approximately 50% of the substrate area, the total average metal thickness removed was approximately half of the SHR for all three pad types.

Keywords

Copper ECMP BTA Planarization Potassium phosphate 

Notes

Acknowledgments

We would like to kindly thank Jeng-Yu Lin and Neha Solanki for their help in fabricating patterned structures. Additionally, we thank the Semiconductor Research Corporation, under task number 425.016, for financially supporting this research.

References

  1. 1.
    Zantye PB, Kumar A, Sikder AK (2004) Mater Sci Eng R Rep 45:89CrossRefGoogle Scholar
  2. 2.
    Ishikawa A, Shishida Y, Yamanishi T, Hata N, Nakayama T et al (2006) J Electrochem Soc 153:G692CrossRefGoogle Scholar
  3. 3.
    Aksu S, Emesh I, Uzoh C, Basol B (2006) ECS Trans 2Google Scholar
  4. 4.
    Goonetilleke PC, Roy D (2008) Appl Surf Sci 254:2696CrossRefGoogle Scholar
  5. 5.
    West AC, Deligianni H, Andricacos PC (2005) IBM J Res Dev 49:37CrossRefGoogle Scholar
  6. 6.
    Liu FQ, Du TB, Duboust A, Tsai S, Hsu WY (2006) J Electrochem Soc 153:C377CrossRefGoogle Scholar
  7. 7.
    Oh YJ, Park GS, Chung CH (2006) J Electrochem Soc 153:G617CrossRefGoogle Scholar
  8. 8.
    Jeong S, Lee S, Jeong H (2008) Microelectron Eng 85:2236CrossRefGoogle Scholar
  9. 9.
    Suni II, Du B (2005) IEEE Trans Semicond Manuf 18:341CrossRefGoogle Scholar
  10. 10.
    Truque D, Xie X, Boning D (2007) Mater Res Soc Symp Proc 991:315Google Scholar
  11. 11.
    Shattuck KG, Lin J-Y, Cojocaru P, West AC (2008) Electrochim Acta 53:8211CrossRefGoogle Scholar
  12. 12.
    Muthukumaran A, Lowalekar V, Raghavan S (2006) Mater Res Soc Symp Proc 914:231Google Scholar
  13. 13.
    West AC, Shao I, Deligianni H (2005) J Electrochem Soc 152:C652CrossRefGoogle Scholar
  14. 14.
    Tripathi A, Burkhard C, Suni II, Li Y, Doniat F et al (2008) J Electrochem Soc 155:H918CrossRefGoogle Scholar
  15. 15.
    Lin J-Y, West AC, Wan C-C (2008) J Electrochem Soc 155:H396CrossRefGoogle Scholar
  16. 16.
    Finsgar M, Lesar A, Kokalj A, Milosev I (2008) Electrochim Acta 53:8287CrossRefGoogle Scholar
  17. 17.
    Willey MJ, West AC (2007) J Electrochem Soc 154:D156CrossRefGoogle Scholar
  18. 18.
    Vidal R, West AC (1995) J Electrochem Soc 142:2689CrossRefGoogle Scholar
  19. 19.
    Vidal R, West AC (1995) J Electrochem Soc 142:2682CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  1. 1.Department of Chemical EngineeringColumbia UniversityNew YorkUSA

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