Fabrication of Graphoepitaxial Gate-All-Around Si Circuitry Patterned Nanowire Arrays Using Block Copolymer Assisted Hard Mask Approach.

We demonstrate the fabrication of sub-20 nm gate-all-around silicon (Si) nanowire field effect transistor structures using self-assembly. To create nanopatterned Si feature arrays, a block-copolymer-assisted hard mask approach was utilized using a topographically patterned substrate with well-defined SiN features for graphoepitaxially alignment of the self-assembled patterns. Microphase-separated long-range ordered polystyrene--poly(ethylene oxide) (PS--PEO) block-copolymer-derived dot and line nanopatterns were achieved by a thermo-solvent approach within the substrate topographically defined channels of various widths and lengths.

Area Selective Polymer Brush Deposition.

Polymer brush films with chemical functionality to attach to site specific substrate areas are introduced for area selective deposition (ASD) application. It is demonstrated that polymer brushes with chemically defined end sites can be selectively bound to copper-specific regions of patterned copper/silica (Cu/SiO ) substrates. The process described overcomes various limitations of currently used technology including cost, complexity, and throughput, with potential implications for future electronic devices and nanomanufacturing.

Morphological evolution of lamellar forming polystyrene-block-poly(4-vinylpyridine) copolymers under solvent annealing.

In this work, we are reporting a very simple and efficient method to form lamellar structures of symmetric polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) copolymer thin films with vertically (to the surface plane) orientated lamellae using a solvent annealing approach. The methodology does not require any brush chemistry to engineer a neutral surface and it is the block neutral nature of the film-solvent vapour interface that defines the orientation of the lamellae. The microphase separated structure of two different molecular weight lamellar forming PS-block-P4VP copolymers formed under solvent vapour annealing was monitored using atomic force microscopy (AFM) so as to understand the morphological changes of the films upon different solvent exposure.

Fabrication of ultra-dense sub-10 nm in-plane Si nanowire arrays by using a novel block copolymer method: optical properties.

The use of a low-χ, symmetric block copolymer as an alternative to the high-χ systems currently being translated towards industrial silicon chip manufacture has been demonstrated. Here, the methodology for generating on-chip, etch resistant masks and subsequent pattern transfer to the substrate using ultra-small dimension, lamellar, microphase separated polystyrene-b-poly(ethylene oxide) (PS-b-PEO) block copolymer (BCP) is described. Well-controlled films of a perpendicularly oriented lamellar pattern with a domain size of ∼8 nm were achieved through amplification of an effective interaction parameter (χeff) of the BCP system.

Reduction and control of domain spacing by additive inclusion: morphology and orientation effects of glycols on microphase separated PS-b-PEO.

Cylindrical phase polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer (BCP) was combined with lower molecular weight poly/ethylene glycols at different concentrations and their effect on the microphase separation of BCP thin films were studied. Well-ordered microphase separated, periodic nanostructures were realized using a solvent annealing approach for solution cast thin films. By optimizing solvent exposure time, the nature and concentration of the additives etc.

Fabrication of ordered, large scale, horizontally-aligned si nanowire arrays based on an in situ hard mask block copolymer approach.

A simple technique is demonstrated to fabricate horizontal, uniform, and hexagonally arranged Sinanowire arrays with controlled orientation and density at spatially well defined locations on a substrate based on an in situ hard-mask pattern-formation approach by microphase-separated block-copolymer thin films. The technique may have significant application in the manufacture of transistor circuitry.

Size and space controlled hexagonal arrays of superparamagnetic iron oxide nanodots: magnetic studies and application.

Highly dense hexagonally arranged iron oxide nanodots array were fabricated using PS-b-PEO self-assembled patterns. The copolymer molecular weight, composition and choice of annealing solvent/s allows dimensional and structural control of the nanopatterns at large scale. A mechanism is proposed to create scaffolds through degradation and/or modification of cylindrical domains.

Sub-10 nm feature size PS-b-PDMS block copolymer structures fabricated by a microwave-assisted solvothermal process.

Block copolymer (BCP) microphase separation at surfaces might enable the generation of substrate features in a scalable, manufacturable, bottom-up fashion provided that pattern structure, orientation, alignment can be strictly controlled. A further requirement is that self-assembly takes place within periods of the order of minutes so that continuous manufacturingprocesses do not require lengthy pretreatments and sample storageleading to contamination and large facility costs. We report here microwave-assisted solvothermal (in toluene environments) self-assembly and directed self-assembly of a very low molecular weight cylinder-forming polystyrene-block-polydimethylsiloxane (PS-b-PDMS) BCP on planar and patterned silicon nitride (Si3N4) substrates.

Molecularly functionalized silicon substrates for orientation control of the microphase separation of PS-b-PMMA and PS-b-PDMS block copolymer systems.

The use of block copolymer (BCP) thin films to generate nanostructured surfaces for device and other applications requires precise control of interfacial energies to achieve the desired domain orientation. Usually, the surface chemistry is engineered through the use of homo- or random copolymer brushes grown or attached to the surface. Herein, we demonstrate a facile, rapid, and tunable approach to surface functionalization using a molecular approach based on ethylene glycol attachment to the surface.

Fabrication of a sub-10 nm silicon nanowire based ethanol sensor using block copolymer lithography.

This paper details the fabrication of ultrathin silicon nanowires (SiNWs) on a silicon-on-insulator (SOI) substrate as an electrode for the electro-oxidation and sensing of ethanol. The nanowire surfaces were prepared by a block copolymer (BCP) nanolithographic technique using low molecular weight symmetric poly(styrene)-block-poly(methyl methacrylate) (PS-b-PMMA) to create a nanopattern which was transferred to the substrate using plasma etching. The BCP orientation was controlled using a hydroxyl-terminated random polymer brush of poly(styrene)-random-poly(methyl methacrylate) (HO-PS-r-PMMA).

Orientation and alignment control of microphase-separated PS-b-PDMS substrate patterns via polymer brush chemistry.

Block copolymer (BCP) microphase separation at substrate surfaces might enable the generation of substrate features in a scalable, bottom-up fashion, provided that the pattern structure, orientation, and alignment can be strictly controlled. The PS-b-PDMS (polystyrene-b-polydimethylsiloxane) system is attractive because it can form small features and the two blocks can be readily differentiated during pattern transfer. However, PS-b-PDMS offers a considerable challenge, because of the chemical differences in the blocks, which leads to poor surface wetting, poor pattern orientation control, and structural instabilities.

The sensitivity of random polymer brush-lamellar polystyrene-b-polymethylmethacrylate block copolymer systems to process conditions.

The use of random copolymer brushes (polystyrene-r-polymethylmethacrylate--PS-r-PMMA) to 'neutralise' substrate surfaces and ordain perpendicular orientation of the microphase separated lamellae in symmetric polystyrene-b-polymethylmethacrylate (PS-b-PMMA) block copolymers (BCPs) is well known. However, less well known is how the brushes interact with both the substrate and the BCP, and how this might change during thermal processing. A detailed study of changes in these films for different brush and diblock PS-b-PMMA molecular weights is reported here.

"In situ" hard mask materials: a new methodology for creation of vertical silicon nanopillar and nanowire arrays.

A novel, simple and in situ hard mask technology that can be used to develop high aspect ratio silicon nanopillar and nanowire features on a substrate surface is demonstrated. The technique combines a block copolymer inclusion method that generates nanodot arrays on substrate and an inductively coupled plasma (ICP) etch processing step to fabricate Si nanopillar and nanowire arrays. Iron oxide was found to be an excellent resistant mask over silicon under the selected etching conditions.

Large-scale parallel arrays of silicon nanowires via block copolymer directed self-assembly.

Extending the resolution and spatial proximity of lithographic patterning below critical dimensions of 20 nm remains a key challenge with very-large-scale integration, especially if the persistent scaling of silicon electronic devices is sustained. One approach, which relies upon the directed self-assembly of block copolymers by chemical-epitaxy, is capable of achieving high density 1 : 1 patterning with critical dimensions approaching 5 nm. Herein, we outline an integration-favourable strategy for fabricating high areal density arrays of aligned silicon nanowires by directed self-assembly of a PS-b-PMMA block copolymer nanopatterns with a L(0) (pitch) of 42 nm, on chemically pre-patterned surfaces.

Surface-directed dewetting of a block copolymer for fabricating highly uniform nanostructured microdroplets and concentric nanorings.

Through a combination of nanoimprint lithography and block copolymer self-assembly, a highly regular dewetting process of a symmetric diblock copolymer occurs whereby the hierarchal formation of microdroplets and concentric nanorings emerges. The process is driven by the unique chemical properties and geometrical layout of the underlying patterned silsesquioxane micrometer-sized templates. Given the presence of nonpreferential substrate-polymer interactions, directed dewetting was utilized to produce uniform arrays of microsized droplets of microphase separated polystyrene-block-poly(methyl methylacrylate) (PS-b-PMMA), following thermal annealing at 180 °C.

Study on the combined effects of solvent evaporation and polymer flow upon block copolymer self-assembly and alignment on topographic patterns.

Microphase separation of a polystyrene-block-polyisoprene-block-polystyrene triblock copolymer thin film under confined conditions (i.e., graphoepitaxy) results in ordered periodic arrays of polystyrene cylinders aligned parallel to the channel side-wall and base in a polyisoprene matrix.

Synthesis and characterization of highly ordered cobalt-magnetite nanocable arrays.

Magnetically tunable, high-density arrays of coaxial nanocables within anodic aluminum oxide (AAO) membranes have been synthesized. The nanocables consist of magnetite nanowires surrounded by cobalt nanotube sheaths and cobalt nanowires surrounded by magnetite nanotube sheaths. These materials are a combination of separate hard (Co) and soft (Fe3O4) magnetic materials in a single nanocable structure.