Multiphoton photoresists giving nanoscale resolution that is inversely dependent on exposure time

Abstract

Recent advances in materials science have made it possible to perform photolithography at the nanoscale using visible light. One approach to visible-light nanolithography (resolution augmentation through photo-induced deactivation) uses a negative-tone photoresist incorporating a radical photoinitiator that can be excited by two-photon absorption. With subsequent absorption of light, the photoinitiator can also be deactivated before polymerization occurs. This deactivation step can therefore be used for spatial limitation of photopatterning. In previous work, continuous-wave light was used for the deactivation step in such photoresists. Here we identify three broad classes of photoinitiators for which deactivation is efficient enough to be accomplished by the ultrafast excitation pulses themselves. The remarkable properties of these initiators result in the inverse scaling of lithographic feature size with exposure time. By combining different photoinitiators it is further possible to create a photoresist for which the resolution is independent of exposure over a broad range of fabrication speeds. A broad new class of commercially available multiphoton photoinitiators is identified, the properties of which result in the inverse scaling of photolithographic feature size with exposure time, rather than the usual proportional scaling. On combination with a conventional initiator, photoresists can be created for which the feature size is independent of exposure.

Cite this article

Stocker, M., Li, L., Gattass, R. et al. Multiphoton photoresists giving nanoscale resolution that is inversely dependent on exposure time. Nature Chem 3, 223–227 (2011). https://doi.org/10.1038/nchem.965

View full text

>> Full Text:   Multiphoton photoresists giving nanoscale resolution that is inversely dependent on exposure time