Nanosphere Lithography-Based Fabrication of Spherical Nanostructures and Verification of Their Hexagonal Symmetries by Image Analysis

Abstract

Nanosphere lithography (NSL) is a cost- and time-effective technique for the fabrication of well-ordered large-area arrays of nanostructures. This paper reviews technological challenges in NSL mask preparation, its modification, and quality control. Spin coating with various process parameters (substrate wettability, solution properties, spin coating operating parameters) are discussed to create a uniform monolayer from monodisperse polystyrene (PS) nanospheres with a diameter of 0.2–1.5 μm. Scanning electron microscopy images show that the PS nanospheres are ordered into a hexagonal close-packed monolayer. Verification of sphere ordering and symmetry is obtained using our open-source software HEXI, which can recognize and detect circles, and distinguish between hexagonal ordering and defect configurations. The created template is used to obtain a wide variety of tailor-made periodic structures by applying additional treatments, such as plasma etching (isotropic and anisotropic), deposition, evaporation, and lift-off. The prepared highly ordered nanopatterned arrays (from circular, triangular, pillar-shaped structures) are applicable in many different fields (plasmonics, photonics, sensorics, biomimetic surfaces, life science, etc.).

Fabricating an Ordered Array of Silver Nanoparticles $via$ the Nanosphere Lithography Technique

“…These nanospheres have been assembled on both glass and silicon substrates. It is evident from the picture that the convective self-assembly process [24] can be employed to fabricate nanospheres on a substrate of significant size.…”

“…This confinement is due to a combination of electrostatic and capillary forces, as well as the hydrophobic properties of the nanospheres' surfaces [22]. Various techniques such as doctor blade [23], spin coating [24], Langmuir-Blodgett [25], drop casting [26], and dip-coating [27] can be used to create selfassembled monolayers. The spherical nanoparticles are arranged in hexagonal close-packed (h.c.p.)…”

Low-Cost Preparation of Diamond Nanopillar Arrays Based on Polystyrene Spheres

“…However, controlling the diameter of these masks proves challenging, resulting in the fabrication of diamond nanowires with diameters typically in the range of a few tens of nanometers. Domonkos and Kromka, 27 on the other hand, have demonstrated the formation of well-ordered array films through the self-assembly of polystyrene (PS) spheres. Unfortunately, the low etch resistance of PS spheres makes them unsuitable as etching masks for diamond.…”

Selective Patterned Growth of ZnO Nanoneedle Arrays

“…There is a large number of physical and chemical methods for obtaining nanostructures, including physical dispersion [18], condensation from liquid [19], [20] and gas phases [21], combustion methods [22], plasma-chemical methods [23], synthesis of nanoparticles from solution [24], [25], solgel synthesis [26]- [28], and lithographic [29], [30] and probe methods [31].…”