Nanotransfer printing (nTP) has attracted considerable attention due to its good pattern resolution, process simplicity, and cost-effectiveness. However, the development of a large-area nTP process has been hampered by critical reliability issues related to the uniform replication and regular transfer printing of functional nanomaterials. Here, we present a very practical thermally assisted nanotransfer printing (T-nTP) process that can easily produce well-ordered nanostructures on an 8-inch wafer via the use of a heat-rolling press system that provides both uniform pressure and heat. We also demonstrate various complex pattern geometries, such as wave, square, nut, zigzag, and elliptical nanostructures, on diverse substrates via T-nTP. Furthermore, we demonstrate how to obtain a high-density crossbar metal-insulator-metal memristive array using a combined method of T-nTP and directed self-assembly. We expect that the state-of-the-art T-nTP process presented here combined with other emerging patterning techniques will be especially useful for the large-area nanofabrication of various devices.
The
self-assembly of block copolymers (BCPs) has attracted considerable
attention because it can effectively generate highly ordered nanostructures
through a simple and cost-effective process. However, in BCP annealing
systems, there remain several challenges and issues that must be resolved
to achieve more rapid and tunable pattern formation of BCPs with a
high Flory–Huggins parameter (χ) for next-generation
lithography applications. Here, we introduce a useful annealing technique
to induce a rapid morphological transition of sphere-forming poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) BCPs by
employing multistep solvent vapor annealing (MSVA) and a combined
annealing process of solvent vapor annealing (SVA) and immersion annealing
(IA). We successfully obtained well-ordered sub-20 nm line, dot, core–shell
dot, and core–shell line structures with a short annealing
time (<25 min) based on the synergetic effects of the combined
annealing method which provides both the fast self-assembly kinetics
and a wide range of pattern geometries. Furthermore, we demonstrate
how the repeated process of SVA and IA affects the morphological stability
of self-assembled BCPs, showing highly ordered solid and core–shell
BCP nanostructures even after ten cycles of the repeated annealing
process. We expect that these results will provide a new guideline
to manipulate diverse BCP nanostructures effectively for nanodevice
fabrication by combining various annealing methods.
Unusual pattern generation of various 2D and 3D nanostructures can be achieved by the multiple self-assembly of block copolymers (BCPs) such as big-dot, double-dot, line-on-dot, pondering, dot-in-honeycomb, dot-in-pondering, and line-on-pondering patterns.
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