Comparison of monomer and polymer resists in thermal nanoimprint lithography

Abstract

In this article, the authors compare a polymer resist to a thermally curable monomer resist in a full 8in. wafer thermal nanoimprint lithography process. Using exactly the same imprinting conditions, the authors compare the printing quality and investigate the resist distribution through large area gratings (6×6mm2) with various densities. It is shown that a liquid monomer solution greatly enhance the printing uniformity because of a much wider resist redistribution and flow during the process. Redistribution of the monomer resist is observed over an entire grating, while it is observed only over a few periods of a grating for the polymer in the same conditions. Furthermore, a low molecular weight resist allows reducing the imprinting force as well as the total cycle time.

High flowability monomer resists for thermal nanoimprint lithography

“…In the monomer-based resists, 2% in weight of lauroylperoxide (Sigma Aldrich) is added to allow thermally activated radical polymerization. The best curing temperature (130 °C), to ensure a maximal conversion ratio of the monomers, was determined using modulated differential scanning calorimetry (Q200 model from TA Instruments) [7]. The extent of the polymerization upon heat exposure is evaluated by means of Fourier-transform infrared spectroscopy [8].…”

Flexible fabrication and applications of polymer nanochannels and nanoslits

“…64,65 After the pioneering work on nanoimprint lithography (NIL) by Chou et al demonstrating patterns of 25 nm diameter holes in a PMMA film and the subsequent fabrication of metal pillars by metal deposition and lift-off, 64,65 considerable efforts have been devoted to overcome many challenges associated with NIL. Such efforts include understanding fundamentals related to the process, such as polymer flow behavior during molding and stress and deformation of molded polymers during demolding, 66–83 developing optimal materials applicable to the NIL process, 84–95 overcoming the overlay issue, 96–104 fabricating reliable stamps with sub-100 nm features, 105–122 and improving anti-stick coatings. 123–129 NIL has become very successful in patterning structures to sub-10 nm scales, 64,130–132 with the ultimate resolution seemingly determined by the minimum feature size associated with the molding tool.…”

“…64,65 After the pioneering work on nanoimprint lithography (NIL) by Chou et al demonstrating patterns of 25 nm diameter holes in a PMMA film and the subsequent fabrication of metal pillars by metal deposition and lift-off, 64,65 considerable efforts have been devoted to overcome many challenges associated with NIL. Such efforts include understanding fundamentals related to the process, such as polymer flow behavior during molding and stress and deformation of molded polymers during demolding, [66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83] developing optimal materials applicable to the NIL process, [84][85][86][87][88][89][90][91][92][93][94][95] overcoming the overlay issue, [96][97][98][99][100][101][102][103][104] fabricating reliable stamps with sub-100 nm features, [105][106]…”

Direct nanoimprinting of metal oxides by in situ thermal co-polymerization of their methacrylates

“…In spite of these advantages of liquid resists, there is hardly any work in using them to pattern materials using thermal nanoimprint lithography. 29,30 To fill this gap, in this work we propose to combine alkoxide-based chemistry with methacrylate chemistry to form liquid metal methacrylate resins capable of undergoing in situ thermal free radical co-polymerization to directly pattern oxides using silicon molds. Our preliminary work on imprinting of TiO 2 via this route has shown considerable amount of promise.…”