(The) size and shape control of nanopatterns by combined nanoimprint and soft lithography and the novel nanotransfer printing method

Abstract

Nanometer-scale patterning by lithography is required to fabricate electronic and optical devices. Critical issues, such as resolution, reliability, speed, and overlay accuracy, all need to be addressed in order to develop new lithography methodologies for such demanding, industrially relevant processes. Several approaches towards nanostructure fabrication have been exploited without resorting to expensive tools such as those used in deep-UV projection lithography and electron-beam lithography. In this thesis, nanopatterning with high fidelity and excellent uniformity was achieved using combined nanoimprint and soft lithography referred to as capillary force lithography (CFL) and nanotransfer printing of nanopatterns onto flexible and transparent substrate. As the patterning strategy, CFL could generate many different complex structures from a single pre-pattern that is either prepared from a master mold or stamped onto a solid substrate by patterning with a PDMS replica mold. Various sizes of gold line-shaped patterns were successfully generated from single line-shaped master by controlling the CFL conditions such as annealing time, initial polymer layer thickness, and RIE time. The pattern size is decreased by decreasing annealing time, decreasing initial polymer layer layer thickness, and increasing RIE time. Various shapes of gold dot-shaped patterns were also successfully generated by rotating second PDMS mold with different direction of patterned substrate. After fabrication of micro or nano sized line-shaped patterns as a first cycle, the patterned substrate is used again as a substrate for the second cycle of CFL. When the other stamp is placed on the pattern formed with this second stamp rotated by a certain angle with respect to the first stamp, only overlapped parts are remained that the pattern is like dot shaped such as rhomboidal, rectangle and square shapes after etching process. It also enable the practical generation of nano-sized patterns f...