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Microlens array fabrication by backside exposure using Fraunhofer diffraction

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Abstract

In UV-lithography, a gap between photoresist and UV-mask results in diffraction. Fresnel or near-field diffraction in thick positive and negative resists for microstructures resulting from a small gap in contact or proximity printing has been previously investigated. In this work, Fraunhofer or far-field diffraction is utilized to form microlens arrays. Backside-exposure of SU-8 resist through Pyrex 7740 transparent glass substrate is conducted. The exposure intensity profile on the interface between Pyrex 7740 glass wafer and negative SU-8 resist is modeled taking into account Fraunhofer diffraction for a circular aperture opening. The effects of varying applied UV-doses and aperture diameters on the formation of microlens arrays are described. The simulated surface profile shows a good agreement with the experimentally observed surface profiles of the microstructures. The paper demonstrates the ease with which a microlens array can be fabricated by backside exposure technique using Fraunhofer diffraction.

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References

  • Cheng Y, Lin CY, Wei DH, Loechel B, Gruetzner G (1999) Wall profile of thick photoresist generated via contact printing. IEEE J Microelectromech Syst 8:18–26

    Article  Google Scholar 

  • Chuang YJ, Tseng FG, Lin WK (2002) Reduction of diffraction effect of UV exposure on SU-8 negative thick photoresist by air gap elimination. Microsyst Technol 8:308–313

    Article  Google Scholar 

  • Hacht E (2002a) Optics, chap 10, 4th edn. Addison-Wesley, San Francisco

    Google Scholar 

  • Hacht E (2002b) Optics, chap 4, 4th edn. Addison-Wesley, San Francisco

    Google Scholar 

  • Kim K, Park DS, Lu HM, Che W, Kim K, Lee JB, Ahn CH (2004) A tapered hollow metallic microneedle array using backside exposure of SU-8. J Micromech Microeng 14:597–603

    Article  Google Scholar 

  • Peterman MC, Huie P, Bloom DM, Fishman HA (2003) Building thick photoresist structures from the bottom up. J Micromech Microeng 13:380–382

    Article  Google Scholar 

  • Song IH, Jin Y, Ajmera PK (2007) Fabrication of a polymeric tapered HARMs array utilizing a low-cost nickel electroplated mold insert. Microsyst Technol 13:297–291

    Article  Google Scholar 

  • Zhang J, Chan-Park MB, Conner SR (2004) Effect of exposure dose on the replication fidelity and profile of very high aspect ratio microchannels in SU-8. Lab Chip 4:646–653

    Article  Google Scholar 

Download references

Acknowledgments

The authors would like to thank the Center for Advanced Microstructures and Devices (CAMD) for the use of the microfabrication facilities. Any opinions, findings, and conclusions or recommendations expressed here are solely those of the authors.

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Authors and Affiliations

  1. Department of Physics Engineering, École Polytechnique de Montréal, H3C 3A7, Montréal, QC, Canada

    In-Hyouk Song

  2. Department of Electrical and Computer Engineering, Louisiana State University, Baton Rouge, LA, 70803, USA

    Kyung-Nam Kang & Pratul K. Ajmera

  3. Center for Advanced Microstructures and Devices, Louisiana State University, Baton Rouge, LA, 70806, USA

    Yoonyoung Jin

  4. Center for BioModular Multi-scale Systems, Louisiana State University, Baton Rouge, LA, 70803, USA

    Daniel S.-W. Park

Authors
  1. In-Hyouk Song
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  2. Kyung-Nam Kang
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  3. Yoonyoung Jin
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  4. Daniel S.-W. Park
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  5. Pratul K. Ajmera
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Correspondence to In-Hyouk Song.

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Song, IH., Kang, KN., Jin, Y. et al. Microlens array fabrication by backside exposure using Fraunhofer diffraction. Microsyst Technol 14, 1285–1290 (2008). https://doi.org/10.1007/s00542-007-0510-2

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  • DOI: https://doi.org/10.1007/s00542-007-0510-2

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