High-resolution, high-aspect-ratio iridium–nickel composite nanoimprint molds

Abstract

Nanoimprint molds are traditionally made from silicon. Silicon molds suffer from distinct disadvantages as they are brittle, prone to damage, scratch easily, and can only be used in a planar format. This has limited their use in higher throughput systems where flexible molds are required such as in roll-to-roll and roll-to-plate systems. Nickel (Ni) molds, which are now de-rigueur in both batch and roller nanoimprint processes, can be used to address these problems, but fabrication and durability issues limit their availability and effectiveness in production. In this report, the authors introduce a fabrication route that has the potential to overcome the fabrication, quality, and wear problems of Ni molds. The new process relies on atomic layer deposition to form a smooth and highaspect ratio patterned layer of iridium (Ir) on a Ni substrate. A large area nanohole array mold was fabricated using displacement Talbot lithography to demonstrate this process. The authors show the use of such composite molds via a batch thermal imprinting process to fabricate 70 nm hole arrays onto polycarbonate templates with a 610% tolerance in diameter between the polycarbonate and the composite mold, and less than 1% of defects. V

A Rapid Thermal Nanoimprint Apparatus through Induction Heating of Nickel Mold

“…The glass transition temperature of the PMMA we used was 120 °C. The nickel mold with a thickness of 0.5 mm and diameter of 10 cm was replicated from a silicon master mold by electroforming [58,59,60]. Nanostructure on the nickel mold was a 600-nm pitch hexagonal array of nanodots with a diameter of 300 nm and height of 250 nm.…”

Understanding resolution limit of displacement Talbot lithography

“…Applications of this new patterning approach include metamaterials [3], III-V semiconductor photonic materials in the form of core-shell structures [14] and nanotube cavities [15]; neuronal network formation [16] and nanoimprint master creation [17]. The minimum feature size that can be achieved is dependent on the source wavelength, with 125-300 nm features having been achieved for a near-UV laser source [18] and 75 nm features for a deep-UV source [19].…”