Fabrication of a seamless roll mold by direct writing with an electron beam on a rotating cylindrical substrate

Abstract

The fabrication of a seamless roll mold is difficult because of its cylindrical shape. However, seamless nanoscale patterns are in great demand for optical film applications. The authors have therefore developed a method for producing a seamless roll mold by direct writing with an electron beam (EB) onto a layer of resist material coated on a cylindrical substrate as the substrate is rotated in a vacuum. The resist layer is applied to the roll mold substrate by dipping the substrate in poly(methyl methacrylate) (PMMA) solution and then slowly withdrawing it; this coating method gives a uniform layer of resist. The resulting sample is mounted on rotating equipment and installed in an EB writing machine. The developed patterns produced in this case were seamless submicron striped patterns. The mold was used for ultraviolet nanoimprint lithography to give replica pattern that showed that the height of the striped pattern in the PMMA resist almost corresponded to the thickness of the resist. Furthermore, increasing the angle of incidence of the EB increased the sensitivity of the resist because of the resulting increase in the yield of secondary electrons.