Model for large-area monolayer coverage of polystyrene nanospheres by spin coating

Abstract

Nanosphere lithography, an inexpensive and high throughput technique capable of producing nanostructure (below 100 nm feature size) arrays, relies on the formation of a monolayer of self-assembled nanospheres, followed by custom-etching to produce nanometre size features on large-area substrates. A theoretical model underpinning the self-ordering process by centrifugation is proposed to describe the interplay between the spin speed and solution concentration. The model describes the deposition of a dense and uniform monolayer by the implicit contribution of gravity, centrifugal force and surface tension, which can be accounted for using only the spin speed and the solid/liquid volume ratio. We demonstrate that the spin recipe for the monolayer formation can be represented as a pathway on a 2D phase plane. The model accounts for the ratio of polystyrene nanospheres (300 nm), water, methanol and surfactant in the solution, crucial for large area uniform and periodic monolayer deposition. The monolayer is exploited to create arrays of nanoscale features using ‘short’ or ‘extended’ reactive ion etching to produce 30–60 nm (diameter) nanodots or 100–200 nm (diameter) nanoholes over the entire substrate, respectively. The nanostructures were subsequently utilized to create master stamps for nanoimprint lithography.

Palladium‐Decorated Silicon Nanomesh Fabricated by Nanosphere Lithography for High Performance, Room Temperature Hydrogen Sensing

“…A thin Cr protection layer (thickness: 10 nm) was deposited on top of the source and drain regions (Figure S1‐ii, Supporting Information) by electron beam (e‐beam) evaporation to protect the Si layer from being etched in the later PS‐NSL process. A compact PS nanosphere (diameter: 500 nm) monolayer was formed on the substrate via a multistep spin coating process (Figure S1‐iii, Supporting Information) . The PS beads shrunk during exposure to the O 2 plasma using reactive‐ion‐etching (RIE) process, which generated nanometer‐size gaps between individual beads (Figure S1‐iv, Supporting Information).…”

“…PS beads with a diameter of 500 nm (from Polysciences, Inc.) were used in the nanosphere lithography. The compact monolayer of PS beads was formed on substrate via multistep spin coating process . Oxygen (O 2 ) plasma was used to control the size of the beads, creating nanogaps between individual beads.…”

Large‐Area Fabrication of Highly Tunable Hybrid Plasmonic–Photonic Structures Based on Colloidal Lithography and a Photoreconfigurable Polymer

“…Meanwhile, the self‐assembled spheres (or after a particular modification) can also be used as templates to produce various nanostructures in conjugation with different etching or deposition steps. This method, known as CL, has been well established in recent years, and is now recognized as a low‐cost, high‐throughput, scalable, and repeatable nanofabrication technique. In this work, a strategy based on CL has been developed to produce periodic nanohole arrays of a photoreconfigurable polymer deposited on a gold surface.…”

Uniform two-dimensional crystals of polystyrene nanospheres fabricated by a surfactant-assisted spin-coating method with polyoxyethylene tridecyl ether

“…Recently, to improve the solution wettability and to delay the evaporation rates of colloidal suspensions, additional surfactant mixtures were introduced for use in the suspensions 1,4,22,25 . For example, polyethylene glycol tert-octylphenyl ether (Polyoxyethylene octyl phenyl ether, Triton X-100) is a conventional surfactant used to improve the interparticle interaction and delayed evaporation rate of methanol-based suspensions containing colloidal particles of polystyrene nanosphere (PS NS) 4 . However, this approach using the Triton X-100 surfactant is still limited to a few suspensions given their high viscosity levels at high concentrations 26 , making it more difficult to produce a uniform monolayer of nanospheres even with the delayed solvent evaporation rate.…”