Writing self-assembled monolayers with Cs: Optimization of atomic nanolithography imaging using self-assembled monolayers on gold substrates

Abstract

We report the results of a study into the factors controlling the quality of nanolithographic imaging. Self-assembled monolayer (SAM) coverage, subsequent postetch pattern definition, and minimum feature size all depend on the quality of the Au substrate used in material mask atomic nanolithographic experiments. We find that sputtered Au substrates yield much smoother surfaces and a higher density of {111}-oriented grains than evaporated Au surfaces. Phase imaging with an atomic force microscope shows that the quality and percentage coverage of SAM adsorption are much greater for sputtered Au surfaces. Exposure of the self-assembled monolayer to an optically cooled atomic Cs beam traversing a two-dimensional array of submicron material masks mounted a few microns above the self-assembled monolayer surface allowed determination of the minimum average Cs dose (2 Cs atoms per self-assembled monolayer molecule) to write the monolayer. Suitable wet etching, with etch rates of 2.2 nm min-1, results in optimized pattern definition. Utilizing these optimizations, material mask features as small as 230 nm in diameter with a fractional depth gradient of 0.820 nm were realized

Formation of Ordered Two‐Dimensional Polymer Latticeworks With Polygonal Meshes by Self‐Organized Anisotropic Mass Transfer

“…[32] Other etching solutions can also be used according to previous work. [33,34] The porous polymer films always float on the top of the water surface, making it easy to separate them from the underlying substrate. Figure 7A is a photograph of the PS film with a square latticework structure floating on the water surface after etching.…”

Advancing atomic nanolithography: cold atomic Cs beam exposure of alkanethiol self-assembled monolayers

“…Further detailed descriptions of process parameters, etching techniques, laser cooling, material and optical masks and substrate preparation can be found elsehwere [6,7]. Schematically, the exposure and development of the SAM is shown in Fig.…”

In-situ examination of the selective etching of an alkanethiol monolayer covered Au{111} surface

“…Details on the substrate preparation, growth of the SAM and conditions of AFM and STM imaging can be found elsewhere [4,5]. In-situ etching took place in an in-house-fabricated cell amenable to normal AFM operation using a water-based etching solution composed of …”