High-Throughput, Continuous Nanopatterning Technologies for Display and Energy Applications.

Abstract

The motivation of this work is to enable continuous patterning of nanostructures on flexible substrates to push nanoscale lithography to an entirely new level with drastically increased throughput. The Roll-to-Roll Nanoimprint Lithography (R2RNIL) technology presented in this work retains the high-resolution feature capabilities of traditional NIL, but with an increase in throughput by at least one or two orders of magnitude. We demonstrated large-area (4” wide) continuous imprinting of nanogratings by using a newly developed apparatus capable of roll-to-roll imprinting on flexible substrates (R2RNIL) and roll-to-plate imprinting on rigid substrates (R2PNIL). In addition, analytical models were developed to predict the residual layer thickness in dynamic R2RNIL. As a potential application, high-performance metal wire-grid polarizers have also been fabricated utilizing R2RNIL. Another research focus involved Direct Metal Imprinting (DMI) to create discrete nano-scale metal gratings. DMI uses a polymer cushion layer between a thin metal layer and a hard substrate, which enables room-temperature nanoimprinting of the metal by overcoming troublesome hard-to-hard surface contact issues while preserving the Si mold. We also introduced a novel nanofabrication technique, Dynamic Nano-Inscribing (DNI) for creating truly continuous nanograting patterns by using the sharp edge of a tilted Si mold on a variety of metals or polymer materials, creating linewidths down to 50 nm at extremely high speeds (~100 mm/sec) under ambient conditions. Additionally, a new nanograting fabrication method, Localized Dynamic Wrinkling (LDW) has been developed. LDW enables the continuous formation of micro/nano-scale gratings by simply sliding a flat edge of a cleaved Si wafer over the metal film. LDW shares the same basic principle as the buckling (wrinkling) phenomenon but the moving edge of the tilted Si wafer exerts stress on a metal coated polymer and sequentially generates localized winkles in the metal film in a dynamic fashion. The period in LDW can be controlled by several processing parameters and shows good agreement with a theoretical model. Finally, we developed a Dynamic Nano-Cutting (DNC) process using high-frequency indentations on a moving substrate to sequentially create nanograting patterns. DNC provides perfectly straight lines with real-time period modulation, which is difficult to achieve by other nanomanufacturing techniques.