Scanning probe block copolymer lithography

Abstract

Integration of individual nanoparticles into desired spatial arrangements over large areas is a prerequisite for exploiting their unique electrical, optical, and chemical properties. However, positioning single sub-10-nm nanoparticles in a specific location individually on a substrate remains challenging. Herein we have developed a unique approach, termed scanning probe block copolymer lithography, which enables one to control the growth and position of individual nanoparticles in situ. This technique relies on either dip-pen nanolithography (DPN) or polymer pen lithography (PPL) to transfer phase-separating block copolymer inks in the form of 100 or more nanometer features on an underlying substrate. Reduction of the metal ions via plasma results in the high-yield formation of single crystal nanoparticles per block copolymer feature. Because the size of each feature controls the number of metal atoms within it, the DPN or PPL step can be used to control precisely the size of each nanocrystal down to 4.8 AE 0.2 nm.scanning probe lithography | block copolymer micelles | single particle synthesis | nanopatterning N anoparticles exhibit size-dependent photonic, electronic, and chemical properties that could lead to a new generation of catalysts and nanodevices, including single electron transistors, photonics, and biomedical sensors (1-3). In order to realize many of these targeted applications, researchers need ways of synthesizing monodisperse particles while controlling individual particle position on technologically relevant surfaces. The challenge of positioning or synthesizing single sub-10-nm nanoparticles in desired locations is difficult, if not impossible, via current techniques including conventional photolithography (4-7). Scanning probe-based methods such as dip-pen nanolithography (DPN) (8) and polymer pen lithography (PPL) (9) are particularly attractive because inked nanoscale tips can deliver material directly to desired locations on various substrates with high registration and sub-50-nm feature resolution (10). Here we report a unique approach, termed scanning probe block copolymer lithography (SPBCL), which enables one to control individual nanoparticle growth and position in situ by using DPN or PPL to pattern attoliter volumes of metal ions associated with block copolymers in a massively parallel manner over large areas. Reduction of the metal ions via plasma results in the high-yield formation of single crystal nanoparticles per block copolymer feature. Specifically, we demonstrate that pattern dimensions and metal ion concentration dictate the size of each nanoparticle, whose diameter can be controlled with remarkable precision down to 4.8 AE 0.2 nm.To begin, we identified a polymer with two essential properties. The material must transfer from a scanning probe tip to a surface of interest in a controllable way, and it must sequester metal ions which can be used subsequently to make nanoparticles. We evaluated the properties of poly(ethylene oxide)-b-poly(2-vinylpyridine) (PEO-b-P2VP) in thi...

Nanoscale platinum printing on insulating substrates

“…The N 2 plasma treated film has not undergone complete reduction, however, and small peaks associated with non-reduced precursor crystals are evident at 34°, 66° and 78°. The reduction of metal precursor loaded block-copolymer micelles using oxygen plasma has been attributed to a mechanism of hydrocarbon oxidation, however no precise reduction mechanism was elaborated [28,34]. In our case, reduction only takes place using nitrogen or air plasma, and not pure oxygen.…”

“…An electroless deposition methodology for nanoscale platinum printing was described in a US patent, though a potentially destructive high temperature reduction step was required [27]. More recently, the Mirkin group adapted 'block copolymer lithography' for the DPN technique [28]. Their ink was based on block-copolymer micelles loaded with metal ions (AuCl 4 -or HPtCl 6 -).…”

Synthesis and optimization of PEDOT:PSS based ink for printing nanoarrays using Dip-Pen Nanolithography

“…2F of single dot of the customized PEDOT:PSS ink on silicon. Given an expected deviation (over-estimation) due to tip broadening effects, these latter dimensions are comparable with DPN printing 60 of poly (ethylene glycol) based block copolymer on silicon 39 and mixtures of agarose and tricine on glass substrates. 28 The standard deviation of the dot dimensions indicates the degree of uniformity and reproducibility of the patterning, which is also similar to that reported during DPN printing of thiols and acid 65 monolayers deposited on gold.…”

Selectable Nanopattern Arrays for Nanolithographic Imprint and Etch‐Mask Applications

“…The development of rapid and precise nanopatterning methods that are time‐ and cost‐effective is a key to fundamental nanotechnology research, as well as a number of industrial processes. For high‐resolution nanopatterns a number of techniques are well developed, including electron‐/ion‐beam‐based litho­graphy1, 2, 3 and tip‐based lithography,4, 5, 6, 7, 8, 9 but they are often too slow for wafer‐scale processes that demand fast processing times. On the other hand, for large‐area nanopatterning, optical/plasmonic lithography,10, 11, 12, 13, 14, 15 contact printing‐based lithography,16, 17, 18, 19 and template‐assisted lithography20, 21, 22, 23 are promising candidates; however, they require additional expensive and time‐consuming pre‐fabrication processes, such as the preparation of a master template.…”