Combining Nanoimprint Lithography with Dynamic Templating for the Fabrication of Dense, Large-Area Nanoparticle Arrays

Abstract

The study of nanomaterials is a developing science with potentially large benefits in the development of catalysts, optical and chemical sensors, and solid state memory devices. As several of these devices require large arrays of nanoparticles, one of the greatest obstacles in material characterization and device development is the reliable manufacture of nanopatterns over a large surface area. In addition, various applications require different nanoparticle size and density. High density arrays with small nanoparticle sizes are difficult to achieve over a large surface area using current manufacturing processes. Herein, Nanoimprint Lithography (NIL) and Dynamic Templating are combined to create a new manufacturing process capable of developing high density arrays with small nanoparticle sizes. The NIL process involves the stamping of a polymer coated substrate by a silicon stamp with patterned nanofeatures. The stamp is then removed, leaving the pattern in the polymer, which is first etched and then coated with a thin layer of metal, filling the recessed regions of the pattern. The excess polymer is dissolved, leaving a pattern of nanoparticles on the substrate matching the pattern on the stamp. When Dynamic Templating is applied, a very thin layer of metal can be coated, which forms small nanoparticle sizes when dewetted. A custom NIL system has been developed to combine these two processes together, which has now proven to yield consistent large-area, dense arrays with a small nanoparticle size. An array spacing of 700 nm has been achieved, along with a nanoparticle size of 90 nm. Arrays have been created in gold and palladium, where there is now the potential to combine them with other solution-based syntheses which should lead to complex nanoparticle geometries suitable for sensor applications.