Lab talk
Nov 27, 2012
Roll-to-roll nanoimprinting to change nanolithography landscape
Roll-to-roll or continuous roller nanoimprinting is an emerging manufacturing platform that could benefit a range of application areas including nanofluidics, biomedicine, data-storage media and optical elements. The technique is well suited to mass-producing inexpensive high-resolution resin moulds with nanoscale as well as mixed micro- and nanoscale features for downstream contact nanolithography. Resin moulds produced by this method can be fabricated at costs that would allow the mould to be used once and then discarded and recycled. This creates tremendous efficiency gains by eliminating mould-cleaning steps and inherent mould degradation associated with re-use and dramatically improves the cost-production profile for low unit-cost products, which require one or more nanoscale lithography steps.
Researchers at the Institute of Materials Research & Engineering (IMRE) and the National University of Singapore have used UV roll-to-roll nanoimprinting to fabricate high-fidelity resin moulds with nanoscale as well as mixed micro- and nanoscale features down to 50 nm feature diameter, at up to 120 cm2 in area and at a throughput of 10 m min–1.
In the study, the team also examined the effects of multiple iterative or descended copies from a nickel master out to the fourth generation, and through multiple material carrier types (nickel, UV cured acrylic resin, PMMA). Fabricated resin moulds were used in batch mode thermal nanoimprint lithography to demonstrate viability.
The scientists found that the combined feature shrinkage of a single UV curing replication cycle followed by thermal NIL was small enough to avoid substantially affecting replication fidelity and uniformity in terms of measured feature height.
The most significant uniformity bottleneck actually arises from the surface planarity of the resin mould itself, which depends specifically on the uniformity of curvature of the nickel shims and backing surfaces used in UV roll-to-roll nanoimprint fabrication. This highlights the need for engineered surfaces with near-perfect curvature, as well as further studies on defect accumulation after multiple iterative or descended copies with other roll-to-roll compatible mould materials such as fluoropolymers and polysiloxanes.
The researchers presented their results in the journal Nanotechnology.
About the author
This research effort was conducted by teams from the Patterning & Fabrication group at the Institute of Materials Research & Engineering (IMRE), Singapore, as well as the Mechanical Engineering Department of the National University of Singapore (NUS). Funding was provided by Exploit Technologies Pte Ltd (ETPL), and the Science and Engineering Research Council (SERC) of the Agency of Science, Technology and Research (A*STAR), Republic of Singapore. Jarrett Dumond is a staff scientist at IMRE and a mechanical engineering PhD student with NUS who helped design the UV roll-to-roll nanoimprinting apparatus installed at IMRE, fabricated resin mould test samples from it, and performed subsequent characterization and analysis. He was supported by Dr Kambiz Ansari Mahabadi, Yew Sok Yee, Christina Tan and staff researchers at IMRE who fabricated nickel shim moulds and were involved in sample characterization. Prof. Jerry Fuh and Prof. HP Lee are professors at the NUS Mechanical Engineering Department and Dr Low Hong Yee is a senior scientist at IMRE, all of whom played an advisory role and directed the research effort.
