Progress Towards High-Throughput Continuous Nanoimprinting
|Progress towards scaled, large-area NIL for high-throughput roll-to-roll and roll-to-plate processes has been demonstrated, representing a significant step towards integration of emerging nanomanufacturing techniques with high throughput production infrastructure.|
Reviewed by Jeff Morse, Ph.D, National Nanomanufacturing Network
- Ahn SH and G LJ. 2009. Large-Area Roll-to-Roll and Roll-to-Plate Nanoimprint Lithography: A Step toward High-Throughput Application of Continuous Nanoimprinting. ACS Nano AOP. DOI:10.1021/nn9003633.
Nanoimprint lithography (NIL) has emerged as a leading candidate for high throughput, high resolution nanoscale patterning due to the ability to achieve feature resolutions beyond the limits encountered by other techniques, such as optical diffraction or beam scattering . Current issues for NIL include control and removal of the residual layer, which may be critical for some applications and require subsequent process steps, and throughput, which still remains at approximately a few minutes per wafer—insufficient for the production of flat panel displays, photonics, or organic optoelectronics. Growing interest in integrated nanomanufacturing on flexible substrates for these and related applications underscores the need to develop rapid throughput NIL techniques conducive with continuous roll-to-roll processes.
The authors use a flexible fluoropolymer mold material, ethylene tetrafluoroethylene (ETFE), for its exceptional antistick properties—thereby making it relatively easy to demold after imprinting without the need for surface treatment. For fast roll-to-roll process development, the authors use a UV-curable, low-viscosity epoxysilicone as the imprint resist material. The epoxysilicone has the advantage of curing via a cationic mechanism, free from the oxygen inhibition effects and vacuum environment of UV-curing for acrylate-based resists. Additionally, the epoxysilicone exhibits very low shrinkage after curing, enabling high fidelity pattern replication. The authors demonstrate printing of 300nm linewidth gratings with 600nm heights reproducibly patterned on both types of substrates. The rapid curing of the epoxysilicone allowed for a web speed of 1 m/min, which is a significant leap over previously reported performance. Note that the epoxysilicone resist still exhibits insufficient adhesion to the glass substrate and delaminates during the demolding step, therefore requiring that adhesion promoter be applied to the substrate.
Finally, the authors describe an analytical model used to predict RLT dependence on process parameters including web speed and applied force. Incorporating an accurate description of the dynamic force applied during contact between the mold and substrate, the authors improve the accuracy of the model, exhibiting excellent agreement with experiment.
Thus, progress towards scaled, large-area NIL for high-throughput roll-to-roll and roll-to-plate processes has been demonstrated, representing a significant step towards integration of emerging nanomanufacturing techniques with high throughput production infrastructure.
Image reproduced with permission from Ahn SH and G LJ. 2009. Large-Area Roll-to-Roll and Roll-to-Plate Nanoimprint Lithography: A Step toward High-Throughput Application of Continuous Nanoimprinting. ACS Nano AOP. DOI:10.1021/nn9003633. Copyright 2009 American Chemical Society.
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported.