Hostname: page-component-78c5997874-m6dg7 Total loading time: 0 Render date: 2024-11-06T05:12:05.430Z Has data issue: false hasContentIssue false

Negative Contrast Curves for Two-photon Free Radical Polymerization Systems and Their Potential Applications in Sub-diffraction Limited Two-photon Photolithography

Published online by Cambridge University Press:  10 April 2013

Robert J. DeVoe
Affiliation:
3M Corporate Research Materials Labs, St. Paul, MN 55144
Tzu-Chen Lee
Affiliation:
3M Corporate Research Materials Labs, St. Paul, MN 55144
Brian J. Gates
Affiliation:
3M Corporate Research Materials Labs, St. Paul, MN 55144
Get access

Abstract:

Two-photon fabrication is a powerful method of fabricating complex microstructures. Superresolution by methods analogous to stimulated emission depletion (STED) has been described previously, enabling sub-100 nm imaging with 800 nm light. STED-related methods of enhancing imaging resolution require photoresists with exposure conditions for which the photoresist exhibits negative contrast, i.e., image density decreases with increasing exposure from the depletion beam. We have observed decreasing voxel size with increasing exposure during two-photon initiated polymerization of acrylate- and methacrylate-based photoresists, that is, negative imaging contrast, γ < 0, independent of the type of photoinitiator. Negative contrast is not observed in epoxy-type photoresists containing photoacid generators. An investigation of the exposure conditions has led us to conclude that radical-radical recombination at high exposure is responsible for negative contrast. Results of the investigation, discussion of the proposed mechanism for negative contrast and implications for two-photon superresolution will be presented.

Type
Articles
Copyright
Copyright © Materials Research Society 2013

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

DeVoe, Robert J., Lee, Tzu-Chen, Larsen, Jeremy K., Ender, David A., Sahlin, Jennifer J., Sykora, Craig R., Patnaude, Cheryl A., Atkinson, Matthew R., Griffin, Michael E., Gates, Brian J., and Redinger, David H., MRS 2011 Spring Symposium Proceeding, Symposium TT, TT09–14, R1. Google Scholar
Li, Linjie, Gattass, Rafael R., Gershgoren, Erez, Hwang, Hana, Fourkas, John T., Science, Vol. 324, 910, (2009). Timothy F. Scott, Benjamin A. Kowalski, Amy C. Sullivan, Christopher N. Bowman, Robert R. McLeod, Science, Vol. 324, 913, (2009). Joachim Fischer, Georg von Freymann, and Martin Wegener, Advanced Materials, Vol. 22, 3578, (2010). Michael P. Stocker, Linjie Li, Rafael Gattass, and John T. Fourkas, Nature Chemistry, Vol. 3, pp. 223–227, March 2011.CrossRefGoogle Scholar
Leatherdale, C. A., Schardt, C. R., Thompson, D. S., Thompson, W. L., U.S. Patent No. 7,265,161 (4 September 2007). Google Scholar
Leatherdale, C.A. and DeVoe, R.J., SPIE, Vol. 5211, pp. 112123, (2003).Google Scholar