One of the useful applications using NIL is the fabrication of antireflection structure (ARS) which has a sub-wavelength
nanostructure similar to moth-eye below wavelength of visible light because the ARS can be used in anti-glare monitor,
dashboards, and solar cells. The material selection of mold and resin in the NIL process for ARS is very important for
the purpose of real application and mass production. Generally, the mold should have flexibility for continuous mass
production and final structure should have strong durability under outdoor environment. In this work, the effect of single
side and dual side patterning were investigated by change of pitch from moth-eye to photonic crystal on the flexible
polymer substrate by using NIL. Then, the effect of fluorine resin with low refractive index was tested. Finally, a
fabrication method of ARS of pitch of 250nm with high fidelity and accuracy using the high-resolution PDMS mold by
aid of solvent mixing of low viscosity was presented. Generally, it is difficult for Sylgard PDMS to make nanopattern
below 300nm pitch without special treatment.
An etch-less ultraviolet nanoimprint lithography (UV-NIL) process is proposed for patterning a photonic crystal (PC)
structure onto an organic light-emitting diode (OLED) substrate. In a conventional UV-NIL, anisotropic etching is used
to remove the residual layers and to transfer the patterns onto the substrate. The proposed process does not require an
etching process. In the process, a stamp with nano-scale PC patterns is pressed on the dispensed resin and UV light is
then exposed to cure the resin. After tens of seconds, the stamp is separated from the patterned polymer layer on the
substrate. Finally, high-refractive index material is coated onto the layer. The refractive index of the polymer should be
very similar to that of glass. The enhancement of the light extraction was assessed by the three-dimensional (3D) finite
difference time domain (FDTD) method. The OLED was integrated on a nanoimprinted substrate and the electro-luminance
intensity was found to have increased by as much as 50% compared to a conventional device.
We propose a very large-area (> diagonal 20 inch) ultraviolet nanoimprint lithography (UV-NIL) process as a
breakthrough strategy for the thin-film transistor liquid-crystal display (TFT-LCD) industry. The large-area UV-NIL
process is a promising alternative to expensive conventional optical lithography for the production of TFT-LCD panels.
In this study a UV-NIL process using a large area hard stamp in a low vacuum environment is presented. The hard stamp
made from quartz is used for achieving a high overlay accuracy and the vacuum environment is employed to ensure that
air bubble defects are not formed during imprinting. It is demonstrated that the quartz stamp can be used for imprinting
diagonal 20-in. substrates via single-step UV-NIL in a low vacuum environment. Experimental results demonstrate the
potential of the proposed approach as a low-cost lithographic process applicable to flat panel displays.
Two-dimensional (2-D) and three-dimensional (3-D) diamond-like carbon (DLC) stamps for ultraviolet nanoimprint lithography (UV-NIL) were fabricated with two methods: namely, two-photon polymerization (TPP) patterning, followed by nanoscale-thick DLC coating; and a fluorine-doped (F-DLC) coating process, followed by O<sub>2</sub> plasma etching. The DLC layer on top of polymer pattern or flat quartz substrate was formed using radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) process or Direct current (DC) and radio frequency (RF) magnetron sputtering process. It was also demonstrated that the DLC stamp with no anti-adhesion layer could be used for imprinting wafers on UV-NIL and the dimensions of the stamp's features correlated well with the corresponding imprinted features.