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Spatial control of the orientation of block copolymers (BCPs) in thin films offers enormous opportunities for practical nanolithography applications. In this study, we demonstrate the use of a substrate comprised of poly(4-acetoxystyrene) to spatially control interfacial interactions and block copolymer orientation over different length scales. Upon UV irradiation poly(4-acetoxystyrene) undergoes a photo-Fries rearrangement yielding phenolic groups available for further functionalization. The wetting behaviour of PS-b-PMMA deposited on the poly(4-acetoxystyrene) films could be precisely controlled through controlling the UV irradiation dose. After exposure, and a mild post-exposure treatment, the substrate switches from asymmetric, to neutral and then to symmetric wetting. Upon exposure through photomasks, a range of high fidelity micro-patterns consisting of perpendicularly oriented lamellar microdomains were generated. Furthermore, the resolution of chemically patterned poly(4-acetoxystyrene) substrate could be further narrowed to submicrometer scale using electron beam lithography. When the BCP was annealed on an e-beam modified poly(4-acetoxystyrene) surface, the interface between domains of parallel and perpendicular orientation of the BCPs was well defined, especially when compared with the substrates patterned using the photomask.

Genetic tags allow rapid localization of tagged proteins in cells and tissues. APEX, an ascorbate peroxidase, has proven to be one of the most versatile and robust genetic tags for ultrastructural localization by electron microscopy (EM). Here, we describe a simple method, APEX-Gold, which converts the diffuse oxidized diaminobenzidine reaction product of APEX into a silver/gold particle akin to that used for immunogold labelling. The method increases the signal-to-noise ratio for EM detection, providing unambiguous detection of the tagged protein, and creates a readily quantifiable particulate signal. We demonstrate the wide applicability of this method for detection of membrane proteins, cytoplasmic proteins, and cytoskeletal proteins. The method can be combined with different EM techniques including fast freezing and freeze substitution, focussed ion beam scanning EM, and electron tomography. Quantitation of expressed APEX-fusion proteins is achievable using membrane vesicles generated by a cell-free expression system. These membrane vesicles possess a defined quantum of signal, which can act as an internal standard for determination of the absolute density of expressed APEX-fusion proteins. Detection of fusion proteins expressed at low levels in cells from CRISPR-edited mice demonstrates the high sensitivity of the APEX-Gold method.

The introduction of immune checkpoint inhibitors has demonstrated significant improvements in survival for subsets of cancer patients. However, they carry significant and sometimes life-threatening toxicities. Prompt prediction and monitoring of immune toxicities have the potential to maximise the benefits of immune checkpoint therapy. Herein, we develop a digital nanopillar SERS platform that achieves real-time single cytokine counting and enables dynamic tracking of immune toxicities in cancer patients receiving immune checkpoint inhibitor treatment - broader applications are anticipated in other disease indications. By analysing four prospective cytokine biomarkers that initiate inflammatory responses, the digital nanopillar SERS assay achieves both highly specific and highly sensitive cytokine detection down to attomolar level. Significantly, we report the capability of the assay to longitudinally monitor 10 melanoma patients during immune inhibitor blockade treatment. Here, we show that elevated cytokine concentrations predict for higher risk of developing severe immune toxicities in our pilot cohort of patients., There is a clinical need to monitor immune-related toxicities of immune checkpoint blockade therapy. Here, the authors develop a digital SERS platform for multiplexed single cytokine counting to track immune-toxicities and demonstrate the ability to use pre-screening to identify patients at higher risk.

Genetic tags allow rapid localization of tagged proteins in cells and tissues. APEX, an ascorbate peroxidase, has proven to be one of the most versatile and robust genetic tags for ultrastructural localization by electron microscopy. Here we describe a simple method, APEX-Gold, which converts the diffuse oxidized diaminobenzidine reaction product of APEX into a silver/gold particle akin to that used for immunogold labelling. The method increases the signal to noise ratio for EM detection, providing unambiguous detection of the tagged protein, and creates a readily quantifiable particulate signal. We demonstrate the wide applicability of this method for detection of membrane proteins, cytoplasmic proteins and cytoskeletal proteins. The method can be combined with different electron microscopic techniques including fast freezing and freeze substitution, focussed ion beam scanning electron microscopy, and electron tomography. The method allows detection of endogenously expressed proteins in genome-edited cells. We make use of a cell-free expression system to generate membrane particles with a defined quantum of an APEX-fusion protein. These particles can be added to cells to provide an internal standard for estimating absolute density of expressed APEX-fusion proteins.

There is a growing interest and demand to develop sensors that operate at high temperatures. In this work, we investigate the temperature sensing properties of unintentionally doped n-type single crystalline cubic silicon carbide (SiC) for high temperatures up to 800 K. A highly sensitive temperature sensor was demonstrated with a temperature coefficient of conductivity (TCC) ranging from ${1.96}\times {10}^{4}$ to ${5.18}\times {10}^{4}$ ppm/K. The application of this material was successfully demonstrated as a hot film flow sensor with its high signal-to-noise response to air flow at elevated temperatures. The high TCC of the single crystalline SiC film at and above 800 K strongly revealed its potential for highly sensitive thermal sensors working at high temperatures.

The surface roughness in patterned features, commonly termed line-edge roughness (LER), is of particular concern in the manufacture of advanced micro-electronics devices. To address this challenge, we describe an approach whereby the block copolymer poly(oligoethyleneglycol methyl ether methacrylate-stat-styrene)-b-P(N-[3-(dimethylamino)propyl]methacrylamide) (poly(OEGMA-stat-styrene)-b-PDMAPMA) is applied to the patterned photoresist, and after thermal annealing reduces significantly the nanoscale surface roughness. The incorporation of hydrophilic OEGMA units enabled the block polymer to be readily dispersed in water and to self-assemble into particles of less than 10 nm in diameter. Importantly, as a result of the incorporation of a relatively high content of the monomer styrene, excellent plasma etch durability was achieved. The relatively low glass transition temperature of the block copolymer allows thermal annealing at temperatures well below the Tg of the photoresist, enabling effective reduction in LER with minimal change to the profiles of the resist sidewalls and trenches. Partial healing of roughness in lithographic patterns with critical dimensions as low as 25 nm was demonstrated. Finally the relatively high aromatic content of the block copolymer allowed the smoothed patterns to be successfully transferred into the underlying silicon wafer.

Single-crystal cubic silicon carbide has attracted great attention for MEMS and electronic devices. However, current leakage at the SiC/Si junction at high temperatures and visible-light absorption of the Si substrate are main obstacles hindering the use of the platform in a broad range of applications. To solve these bottlenecks, we present a new platform of single crystal SiC on an electrically insulating and transparent substrate using an anodic bonding process. The SiC thin film was prepared on a 150 mm Si with a surface roughness of 7 nm using LPCVD. The SiC/Si wafer was bonded to a glass substrate and then the Si layer was completely removed through wafer polishing and wet etching. The bonded SiC/glass samples show a sharp bonding interface of less than 15 nm characterized using deep profile X-ray photoelectron spectroscopy, a strong bonding strength of approximately 20 MPa measured from the pulling test, and relatively high optical transparency in the visible range. The transferred SiC film also exhibited good conductivity and a relatively high temperature coefficient of resistance varying from -12 000 to -20 000 ppm/K, which is desirable for thermal sensors. The biocompatibility of SiC/glass was also confirmed through mouse 3T3 fibroblasts cell-culturing experiments. Taking advantage of the superior electrical properties and biocompatibility of SiC, the developed SiC-on-glass platform offers unprecedented potentials for high-temperature electronics as well as bioapplications.

We report free-spectral-range tuning in a high-quality on-chip microcavity requiring less than 15 V and 1 nW of power to maintain optical resonance with an arbitrary frequency: an important component for achieving reconfigurable photonic circuits.

An in-depth understanding of the formation of silicon dioxide (SiO2) on silicon carbide (SiC) in thermal oxidation is imperative for micro/nano fabrication processes, integration of electronic components, and evaluation of SiC device performance under extreme conditions. Herein, we report a comprehensive study on the effects of crystalline orientations, thicknesses, and growth temperatures of cubic SiC films on their wet oxidation properties. The oxidation rate and surface morphology were characterized using atomic force microscopy (AFM) and light reflectance measurement systems. Our experimental results revealed the role of defects in the SiC crystal on the oxidation that relates to SiC thickness, deposition conditions, crystal orientation and temperature of wet oxidation. Critically, the electrical properties of SiC films oxidized at 900 °C remained the same as the unoxidized film as confirmed by room-temperature current-voltage measurements, indicating a long-term service temperature of SiC. These findings are expected to provide crucial information on the effects of defects on the formation of SiO2 on SiC films at different oxidation temperatures, which is highly essential for establishing a basic platform for the fabrication of high-performance SiC-based electronic devices.

© 2016 Bentham Science Publishers. Background: The performance of plasmonic nanostructures is based on optical properties and the intensity of the electric field. The nature of the nearfields around coinage metal nanoparticles has been well-studied. However, how to project the enhanced electric field to several hundred nanometers distance might be more convenient for the real applications. Methods: In this paper, we examine whether an array of gold nano-stars may be used as enhancement of the electric field to the several hundred nanometers distance. Electron beam lithography was used to fabricate gold nano-star arrays. Near-field optical properties of these arrays were then obtained using near-field scanning optical microscopy (NSOM). The near-field optical properties were also explored with finite-difference time-domain (FDTD) simulations. Results: In the model, a scanning electron microscope image of actual nano-stars was used to build the FDTD targets of 40 nm thickness. The incident wavelength was 532 nm in both simulation and experiment. In the simulations the near-field optical intensity distribution was studied with monitors positioned at various distances (0, 1 and 2 m above the top surface of a nano-star). The FDTD results were found to be consistent with the experimental NSOM results. Conclusion: We found that the field enhancement is not only localized to the individual nanostars but also projected several hundred nanometers into the space. Such an array could be potential used to probe the intracellular environment of an adjacent cell or near-field imaging.

Electron-beam (e-beam) lithography at a low energy can efficiently write deoxygenated micro-patterns on graphene oxide (GO) films with high edge-definition. The deoxygenation caused by the secondary process of back-scattered electrons leads to a shrinkage of pattern height. A lower energy e-beam is found to be more effective in deoxygenating of GO than that by using a higher energy e-beam. The thickness and the oxygen-to-carbon atomic ratio of the pattern are strongly related that decreases progressively with increasing the electron dosage before reaching a steady level. In addition, as the electron dose increases the patterned area also expanded in lateral direction. The observations of the proximity effect are justified with our results and the Monte Carlo simulation of electrons trajectories. These results can be a guideline for the fabrication of all-carbon thin film electronics.

The interaction of bacteria on nanopatterned surfaces has caught attention since the discovery of the bactericidal property of cicada wing surfaces. While many studies focused on the inspiration of such surfaces, nanolithography-based techniques are seldom used due to the difficulties in fabricating highly dense (number of pillars per unit area), geometrical nanostructured surfaces. Here we present a systematic modelling approach for optimising the electron beam lithography parameters in order to fabricate biomimicked nanopillars of varying patterned geometries. Monte Carlo simulation was applied to optimize the beam energy and pattern design prior to the experimental study. We optimized the processing parameters such as exposure factor, write field size, pitch, the different types and thicknesses of the PMMA resist used, and the shape of the feature (circle or a dot) for the fabrication of nanopillars to achieve the best lift-off with repeatable result. Our simulation and experimental results showed that a circle design with a voltage of 30 kV and 602 nm thickness of PMMA 495 A4 as base layers and 65 nm of PMMA 950 A2 as top layer achieves the best results. The antibacterial activity was also validated on the representative fabricated titanium nanopillar surface. The surface with a base diameter of 94.4 nm, spike diameter of 12.6 nm, height of 115.6 nm, density of 43/μm2, aspect ratio of 2.16 and centre to centre distance of 165.8 nm was the optimum surface for antibacterial activity. Such a systematic design approach for fabrication of insect wing-mimicked closely packed nanopillars have not been investigated before which provides an excellent platform for biomedical Ti implants.

Reconfigurable photonic circuits have applications ranging from next-generation computer architectures to quantum networks, coherent radar and optical metamaterials. However, complete reconfigurability is only currently practical on millimetre-scale device footprints. Here, we overcome this barrier by developing an on-chip high quality microcavity with resonances that can be electrically tuned across a full free spectral range (FSR). FSR tuning allows resonance with any source or emitter, or between any number of networked microcavities. We achieve it by integrating nanoelectronic actuation with strong optomechanical interactions that create a highly strain-dependent effective refractive index. This allows low voltages and sub-nanowatt power consumption. We demonstrate a basic reconfigurable photonic network, bringing the microcavity into resonance with an arbitrary mode of a microtoroidal optical cavity across a telecommunications fibre link. Our results have applications beyond photonic circuits, including widely tuneable integrated lasers, reconfigurable optical filters for telecommunications and astronomy, and on-chip sensor networks., Comment: Main text: 7 pages, 3 figures. Supplementary information: 7 pages, 9 figures

In this paper we image the highly confined long range plasmons of a nanoscale metal stripe waveguide using quantum emitters. Plasmons were excited using a highly focused 633 nm laser beam and a specially designed grating structure to provide stronger incoupling to the desired mode. A homogeneous thin layer of quantum dots was used to image the near field intensity of the propagating plasmons on the waveguide. We observed that the photoluminescence is quenched when the QD to metal surface distance is less than 10 nm. The optimised spacer layer thickness for the stripe waveguides was found to be around 20 nm. Authors believe that the findings of this paper prove beneficial for the development of plasmonic devices utilising stripe waveguides.

© 2015 Published by Elsevier B.V.. Lithography techniques play an important role in the fabrication of nanoscale functional devices. In electron beam lithography (EBL) the optimum dose of electron irradiation is a critical parameter. In this paper, we first identify suitable EBL fabrication parameters by writing patterns with different sizes, periods and electron radiation doses. After finding suitable fabrication parameters, we show how five-pointed gold nanostructures with electric field-enhancing 'top hats' can be fabricated using EBL. Reflectance data of these arrays is measured in order to assess their potential applications in biosensing arrays

Directed self-assembly of block copolymers (BCPs) is a promising technique for the nanofabrication of structures with dimensions smaller than what can be achieved by current photolithography approaches. In particular, there has been significant interest in the development of BCPs that can achieve ever smaller feature sizes with low levels of defects. Here we investigate the directed self-assembly of a high-χ BCP, polystyrene-block-poly(dl-lactide), which is capable of producing structures with dimensions less than 10 nm. In addition, we study the behavior of the BCP under nanoconfinement and the ability of the polymer chains to compress and stretch in response to the geometry of the confining volume. Key findings of this study are that the level of defects in the self-assembled structures are strongly related to the relative interfacial interactions of the BCP as well as the degree of frustration of the polymer chains under nanoconfinement relative to the bulk. These results have particular significance f...

Nanoscale surface roughness is an important factor in determining the properties of surfaces and can affect the performance of a range of devices prepared by lithographic methods. Here, a method is reported, which enables modulation of the nanoscale roughness of surfaces through the directed self assembly (DSA) of positively charged polymersomes, composed of specifically designed block copolymers, onto negatively charged surfaces. Assembly of the polymersomes on surfaces can result in an increase in the nanoscale surface roughness; however, through a controlled annealing step we can also significantly reduce the nanoscale roughness of the original surface. The ability to decrease the roughness of lithographic patterns is expected to have a significant impact on the manufacture of integrated circuits.

Photon-mediated switching of polymer solubility plays a crucial role in the manufacture of integrated circuits by photolithography. Conventional photoresists typically rely on a single switching mechanism based on either a change in polarity or, molecular weight of the polymer. Here we report a photoresist platform that uses both mechanisms. The molecular weight switch was achieved by using a poly(olefin sulfone) designed to undergo photo-induced chain scission. The polarity switch was achieved using pendant groups functionalized with o-nitrobenzyl esters. These are hydrophobic photosensitive-protecting groups for hydrophilic carboxylic acids. On irradiation, they are cleaved, making the polymer soluble in aqueous base. Importantly, the resists do not contain photoacid generator, so do not suffer from problems associated with acid diffusion that are detrimental to pattern fidelity. The 193 nm photochemistry of polymer thin films was followed using grazing angle attenuated total reflectance Fourier transform infrared spectroscopy, variable angle spectroscopic ellipsometry, and measurements of solubility in aqueous base. The nanoscale patterning performance of the polymers was also assessed using 193 nm interference lithography and electron-beam lithography. The implications of using dual switching mechanisms are discussed.

Enormous research studies and funding have been invested into the field of transistor miniaturisation for the last five decades. For the smallest possible MOS transistor, a channel conductance close to that of a metal has been suggested [S.V. Rotkin, K. Hess, Principles of metallic field effect transistor, in: Technical Proceedings of the 2004 NSTI Nanotechnology Conference and Trade Show, vol. 2, 2004, pp. 37-40.]. Metallic nanotransistors are promising candidates that might serve as an alternative solution for overcoming the shrinking limit of conventional MOS structures. This type of transistor operates similarly to depletion type MOSFET by governing the flow of electrons through a narrow channel made from metallic nanowire. In the fabrication of metallic nanotransistors, an electron beam lithography process has been developed to fabricate structures at the sub 30nm scale using silver nanowires on Si"3N"4 substrate. The one-dimensional structure and the use of single material for the construction of the metallic transistors also allow the use of advanced nanoimprint technology for rapid and economic fabrication. This paper details the design, fabrication and characterisation techniques for two structures of all metal nanotransistors.

Directed self-assembly (DSA) is a promising technique for extending conventional lithographic techniques by being able to print features with critical dimensions under 10 nm. The most widely studied block copolymer system is polystyreneblock- polymethyl methacrylate (PS-b-PMMA). The system is well understood in terms of its synthesis, properties and performance in DSA. However, PS-b-PMMA also has a number of limitations that impact on its performance and hence scope of application. The primary limitation is the low Flory-Huggins polymer-polymer interaction parameter (Χ), which limits the size of features that can be printed by DSA. Another issue with block copolymers in general is that specific molecular weights need to be synthesized to achieve desired morphologies and feature sizes. We are exploring blending ionic liquid additiveswithPS-b-PMMAto increase the Χ parameter. This allows smaller feature sizes to be accessed by PS-b-PMMA. Depending on the amount of additive it is also possible to tune the domain size and the morphology of the systems. These findings may expand the scope of PS-b-PMMA for DSA.

Overcoming the resolution-LER-sensitivity trade-off is a key challenge for the development of novel resists and processes that are able to achieve the ITRS targets for future lithography nodes. Here, we describe a process that treats lithographic patterns with aqueous solutions of block copolymers to facilitate a reduction in LER. A detailed understanding of parameters affecting adhesion and smoothing is gained by first investigating the behavior of the polymers on planar smooth and rough surfaces. Once healing was established in these model systems the methodology is tested on lithographically printed features where significant healing is observed, making this a promising technology for LER remediation.

The interactions of block copolymers with surfaces can be controlled by coating those surfaces with appropriate statistical copolymers. Usually, a statistical copolymer comprised of monomer units identical to those of the block copolymer is used; that is, typically a poly(styrene)-stat-poly(methyl methacrylate) (PS-stat-PMMA) is used to direct the alignment of poly(styrene)-block-poly(methyl methacrylate) (PS-block-PMMA), and poly(styrene)-stat-poly(2-vinylpyridine) (PS-stat-P2VP) has been used for poly(styrene)-block-poly(2-vinylpyridine) (PS-block-P2VP). Reports of controlling the orientation of block copolymers with statistical copolymers with a dissimilar composition are limited. Here, we demonstrate that this method can be further extended to show that PS-stat-PMMA can be used to control the wetting properties of poly(styrene)-block-poly(D,L-lactide) (PS-block-PDLA). Surfaces were modified with a series of cross-linked PS-stat-PMMA-stat-glycidyl methacrylate terpolymers, and the surface chemistries and energies were assessed using angle-dependent X-ray photoelectron spectroscopy and the two-liquid harmonic method, respectively. From these experiments, an expected neutral compositional window was identified for symmetrical PS-block-PDLA. Moreover, high-resolution SEM, AD-XPS, and grazing-incidence SAXS measurements were used to evaluate the morphology of PS-block-PDLA as a function of the surface composition of the underlying cross-linked copolymer films, and the neutral composition was found to range from 32 to 38 mol % of PS, in the bulk polymer. Ultimately, we demonstrated the determination of nonpreferential surface compositions that allow the self-assembly of lamellae with sizes in the sub-10 nm regime that are oriented perpendicular to the substrate. These findings have important implications for the use of PS-block-PDLA block copolymers in directed self-assembly, most specifically in advanced lithographic processes.

Directed self assembly (DSA) of block copolymers is an emerging technology for achieving sub-lithographic resolution. We investigate the directed self assembly of tw o systems, polystyrene-block-poly-DL-lactic acid (PS- b-PDLA) and PS-b-poly(methyl methacrylate). For the PS-b-PDLA system we use an open source EUVL resist and a commercially-available underlayer to prepare templates for DSA. We investigate the morphology of the phase separated domains and compare the LER of the resist and the PS-PDLA interface. For the PS- b-PMMA system we again use an open source resist, but the annealing conditions in this case require crosslinking of the resist prior to deposition of the block copolymer. For this system we also i nvestigate the morphology of the phase se parated domains and compare the LER of the resist and the PS-PMMA interface. Keywords: EUVL, LER, directed self assembly, block copolymers, PS- b-PDLA 1. INTRODUCTION With the continuous increase in demand for more powerful and energy efficient computing, higher capacity storage devices, and portable electronics, the rigorous transistor scaling driven by advances in lithography has entered its fifth decade. Among the various candidates for next generation lithography, extreme ultraviolet lithography (EUVL) is arguably the leading candidate to replace 193 nm immersion double pattering for the high volume manufacture of semiconductor devices. This platform is attractive due to the use of a short wavelength ( = 13.4 nm) photon source, which allows for single patterning steps and mask layouts. However, due to the delay in development of EUVL, 193 nm immersion double patterning has remained as the only viable technology for high volume manufacture for the 32 nm and possibly the 22 nm node. There are a number of factors which have contributed to this delay, with the most notable being the low source power. There are however, also issues with the photoresist that need to be addressed to meet the ITRS specifications for the 22 nm node. It is generally accepted that the most critical of these is line edge roughness (LER), which arises predominantly from shot noise and diffusion of photoacid in chemically amplified resists. There has been much work on the development of resists to overcome problems with LER. These include polymer bound PAG resists

The commercialization of 32 nm lithography has been made possible by using double patterning, a technique that allows for an increased pattern density, potentially, through resist freezing and high precision pattern registration. Recent developments in directed self assembly (DSA) also uses resist freezing for stabilizing positive tone resists used in graphoepitaxy. We have developed a method of patterning an open source, positive tone EUV resist using electron beam lithography (EBL), and studied a novel way of freezing a positive tone EUV photoresists through electron beam induced crosslinking. Through metrological analysis, crosslinked pattern was observed to retain consistent critical dimensions (CD) and line-edge roughness (LER) after they were annealed at temperatures higher than the glass transition of the photoresist. This process has been used to freeze patterned EUV photoresists, which have been subsequently used for directed self assembly of PS-b-PMMA and has potential applications in double patterning in an LFLE scenario.

In this work, a focused ion beam (FIB) milling process has been developed to fabricate 50 nm Bi nanowire and transistor structures using FEI‐200 dual beam FIB system. For the fabrication, 50 nm bismuth film was thermally evaporated through EBL patterned PMMA windows onto SiO2 substrates with pre‐defined contact pads. Bi nanowire widths ranging from 30 nm to 100 nm have been successfully fabricated by milling out unwanted areas using 30 KeV Ga+ ion beam. A single‐pixel‐line ion beam blanking technique has been utilised to fabricate Bi nanowire as small as 30 nm in diameter and few micrometers long. In order to form good ohmic contacts for sub 50 nm bismuth nanowires, a drill‐and‐fill process has been developed using FIB to sputter away the surface oxide of bismuth after the in‐situ platinum nanowire contacts deposition. To our knowledge, this is the first time a focused ion beam process has been used to fabricate bismuth nanowire. The fabricated Bi nanowires were electrically characterised using a semicond...

In this paper we excite bound long range stripe plasmon modes with a highly focused laser beam. We demonstrate highly confined plasmons propagating along a 50 µm long silver stripe 750 nm wide and 30 nm thick. Two excitation techniques were studied: focusing the laser spot onto the waveguide end and focusing the laser spot onto a silver grating. By comparing the intensity of the out-coupling photons at the end of the stripe for both grating and end excitation we are able to show that gratings provide an increase of a factor of two in the output intensity and thus out-coupling of plasmons excited by this technique are easier to detect. Authors expect that the outcome of this paper will prove beneficial for the development of passive nano-optical devices based on stripe waveguides, by providing insight into the different excitation techniques available and the advantages of each technique.

Extensive research studies have been devoted into the field of scaling down transistor size for ultra high density integrated circuits over the last three decades. It has been suggested that for the smallest possible scale of MOS transistor channel, a channel conductance close to that of a metal is required (1) metallic nanotransistors are based on field effect transistor made from metallic nanowires. This type of transistor operates by governing the flow of electrons through a narrow channel. In the fabrication of metallic nanotransistors, an electron beam lithography process has been developed to fabricate structures at the sub30 nm scale using silver nanowires on SiN substrate. The single pass line exposure technique in electron beam lithography has been employed to define patterns of transistor structure as small as 20.2nm dimensions. This paper details the design and fabrication techniques of metallic nanotransistors. The limiting issues for writing sub30 nm structures using EBL such as the charging effect of insulating materials, the proximity effects, and the single pass exposures are discussed

Directed self-assembly (DSA) is a promising approach for extending conventional lithographic techniques by being able to print features with critical dimensions under 10 nm. The most widely studied block copolymer system is polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA). This system is well understood in terms of its synthesis, properties, and performance in DSA. However, PS-b-PMMA also has a number of limitations that impact on its performance and hence scope of application. The primary limitation is the low Flory-Huggins polymer-polymer interaction parameter (χ), which limits the size of features that can be printed. Another issue with block copolymers in general is that specific molecular weights need to be synthesized to achieve desired morphologies and feature sizes. Here we explore blending ionic liquid (IL) additives with PS-b-PMMA to increase the χ parameter. ILs have a number of useful properties that include negligible vapor pressure, tunable solvent strength, thermal stability, and chemical stability. The blends of PS-b-PMMA with an IL selective for the PMMA block allowed the resolution of the block copolymer to be improved. Depending on the amount of additive, it is also possible to tune the domain size and the morphology of the systems. These findings may expand the scope of PS-b-PMMA for DSA. © 2014 Society of Photo-Optical Instrumentation Engineers

A series of polymers with a comb architecture were prepared where the poly(olefin sulfone) backbone was designed to be highly sensitive to extreme ultraviolet (EUV) radiation, while the well-defined poly(methyl methacrylate) (PMMA) arms were incorporated with the aim of increasing structural stability. It is hypothesized that upon EUV radiation rapid degradation of the polysulfone backbone will occur leaving behind the well-defined PMMA arms. The synthesized polymers were characterised and have had their performance as chain-scission EUV photoresists evaluated. It was found that all materials possess high sensitivity towards degradation by EUV radiation (E0 in the range 4–6 mJ cm−2). Selective degradation of the poly(1-pentene sulfone) backbone relative to the PMMA arms was demonstrated by mass spectrometry headspace analysis during EUV irradiation and by grazing-angle ATR-FTIR. EUV interference patterning has shown that materials are capable of resolving 30 nm 1 : 1 line : space features. The incorporation of PMMA was found to increase the structural integrity of the patterned features. Thus, it has been shown that terpolymer materials possessing a highly sensitive poly(olefin sulfone) backbone and PMMA arms are able to provide a tuneable materials platform for chain scission EUV resists. These materials have the potential to benefit applications that require nanopattering, such as computer chip manufacture and nano-MEMS.