Tribology and Lubricants

Korean Tribology Society (한국트라이볼로지학회)
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Effect of Pressure on Edge Delamination in Chemical Mechanical Polishing of SU-8 Film on Silicon Wafer

  • Received : 2017.10.28
  • Accepted : 2017.11.18
  • Published : 2017.12.31
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Abstract

SU-8 is an epoxy-type photoresist widely used for the fabrication of high-aspect-ratio (HAR) micro-structures in micro-electro-mechanical systems (MEMS). To fabricate highly integrated structures, chemical mechanical polishing (CMP) has emerged as the preferred manufacturing process for planarizing the MEMS structure. In SU-8 CMP, an oxidizer decomposes organic impurities and particles in the CMP slurry remove the chemically reacted surface of SU-8. To fabricate HAR microstructures using the CMP process, the adhesion between SU-8 and substrate material is important to avoid the delamination of the SU-8 film caused by the mechanical-dominant material removal characteristic. In this study, the friction force during the CMP process is measured with a CMP monitoring system to detect the delamination phenomenon and investigate the delamination of the SU-8 film from the silicon substrate under various pressure conditions. The increase in applied pressure causes an increase in the frictional force and wafer-edge stress concentration. The frictional force measurement shows that the friction force changes according to the delamination phenomenon of the SU-8 film, and that it is possible to monitor the delamination phenomenon during the SU-8 CMP process. The delamination at a high applied pressure is explained by the effect of stress distribution and pad deformation. Consequently, it is necessary to control the pressure of polishing, which can avoid the delamination in SU-8 CMP.

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References

  1. Campo, A.D., Greiner, C., "SU-8: a photoresist for high-aspect-ratio and 3D submicron lithography", J. Micromech. Microeng, Vol. 17, pp. R81-R95, 2007. https://doi.org/10.1088/0960-1317/17/6/R01
  2. Dellmann, L., Roth, S., Beuret, C., Racine, G.-A., Lorenz, H., Despont, M., Renaud, P., Vettiger, P., de Rooij, N. F., "Fabrication process of high aspect ratio elastic and SU-8 structures for piezoelectric motor applications", Sens. Actuators A phys., Vol. 70, pp. 42-47, 1998. https://doi.org/10.1016/S0924-4247(98)00110-1
  3. Madou, M. J., Lu, Y., Lai, S., Koh, C. G., Lee, L. J., Wenner, B. R., "A novel design on a CD disc for 2- point calibration measurement", Sens. Actuators A phys., Vol. 91, pp. 301-306, 2001.
  4. Khoo, H. S., Liu, K.-K., Tseng, F.-G., "Mechanical strength and interfacial failure analysis of cantilevered SU-8 microposts", J. Micromech. Microeng., Vol. 13, pp. 822-831, 2003. https://doi.org/10.1088/0960-1317/13/6/305
  5. Lee, H., Joo, S., Kim, H., Jeong, H., "Chemical Mechanical Planarization Method for Thick Copper Films of Micro-Electro-Mechanical Systems and Integrated Circuits", Jpn. J. Appl. Phys., Vol. 47, No. 7, pp. 5708-5711, 2008. https://doi.org/10.1143/JJAP.47.5708
  6. Zhong, Z. W., Wang, Z. F., Tan, Y. H., "Chemical mechanical polishing of polymeric materials for MEMS applications", Microelectron. J., Vol. 37, pp. 295-301, 2006. https://doi.org/10.1016/j.mejo.2005.05.016
  7. Kourouklis, C., Kohlmeier, T., Gatzen, H. H., "The application of chemical-mechanical polishing for planarizing a SU-8/permalloy combination used in MEMS devices", Sens. Actuators A Phys., Vol. 106, pp. 263-266, 2003. https://doi.org/10.1016/S0924-4247(03)00180-8
  8. Lee, H. S., Jeong, H. D., "Chemical and mechanical balance in polishing of electronic materials for defect-free surfaces", CIRP Ann. Manuf. Technol., Vol. 58, pp. 485-490, 2009. https://doi.org/10.1016/j.cirp.2009.03.115
  9. Yu, H. H., He, M. Y., Hutchinson, J. W., "Edge effects in thin film delamination", Acta Mater., Vol. 49, pp. 93-107, 2001. https://doi.org/10.1016/S1359-6454(00)00293-7
  10. Leduca, P., Savoye, M., Maitrejeana, S., Scevolab, D., Jousseaume, V., Passemard, G., "Understanding CMP-induced delamination in Ultra Low-k/Cu integration", Proc. IEEE Int. Intercon. Technol. Conf., pp. 209-211, 2005.

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