Lithography Templates Research Articles

No-code method for lithography template cell parameterization for faster design cycles

This work presents a Python-based architecture packaged as a standalone tool, to enable the parameterization of lithography structures without the need for scripting. By feeding a lithography template file obtained from an existing layout editor into the tool, a ‘scaffold’ shape is created and recognised. The tool allows for the parameterization of created geometries and the establishment of parameterized rules between geometric features, which can be conveniently modified in tabular format. This work facilitates no-code procedural generation of geometrically distinct instances, significantly reducing the time required for complex lithography template development compared to traditional scripting methods.

Morphology Control of Perpendicularly Oriented Lamellar Films from Azobenzene-Containing Block Copolymers with Different Spacer Lengths

Block copolymer (BCP) films with vertically aligned lamellar structures hold great application potential in multiple fields. Nevertheless, systematic control of the lamellar morphology in BCP films has rarely been reported so far, including connectivity, etch selectivity, and orientation. Here, we report an effective approach to construct perpendicularly oriented lamellar domains by incorporating the azobenzene groups into the side chains of polystyrene-block-polymethacrylate (PS-b-PMMA) with different flexible spacers (x), namely, PS-b-PMA(xC)Az (x = 0, 6, or 11). Two- and three-dimensional vertical lamellae, such as thick high-connectivity lamellae, thin defect-free lamellae, and mixture lamellae, can be fabricated by manipulating x. Simultaneously, the perpendicular lamellae with different morphologies can be obtained on various substrates, such as hard silicon wafers, flexible aluminum sheets, and transparent polyethylene terephthalate (PET) films. Herein, a plausible mechanism is demonstrated. The present strategy might open an avenue to engineer the morphology of perpendicularly aligned lamellar films for applications that either require high-connectivity percolating transport or defect-free lithography templates.

Субволновые текстурированные поверхности для вывода излучения из волновода

A technology for creating textured surfaces by focused-beam ion-beam etching on GaAs (100) substrates is demonstrated. The possibility of flexible control of the shape and profile of the formed submicron elements of textured media is shown. It will make possible to create textured surfaces of almost any complexity for the implementation of surface output of radiation from a waveguide. Original lithographic templates were developed and three-dimensional lithography was carried out. The control of the formed lithographic patterns was carried out by the methods of optical, electron and atomic force microscopy.

Rapid access to discrete and monodisperse block co-oligomers from sugar and terpenoid toward ultrasmall periodic nanostructures

Discrete block co-oligomers (BCOs) are gaining considerable attention due to their potential to form highly ordered ultrasmall nanostructures suitable for lithographic templates. However, laborious synthetic routes present a major hurdle to the practical application. Herein, we report a readily available discrete BCO system that is capable of forming various self-assembled nanostructures with ultrasmall periodicity. Click coupling of propargyl-functionalized sugars (containing 1–7 glucose units) and azido-functionalized terpenoids (containing 3, 4, and 9 isoprene units) afforded the discrete and monodisperse BCOs with a desired total degree of polymerization and block ratio. These BCOs microphase separated into lamellar, gyroid, and cylindrical morphologies with the domain spacing (d) of 4.2–7.5 nm. Considering easy synthesis and rich phase behavior, presented BCO systems could be highly promising for application to diverse ~4-nm nanofabrications.

Improving the optical properties of organic light-emitting diodes using random nanoscale rods with a double refractive index

In this study, random nanoscale rods (RNRs) with a double refractive index were fabricated via spin coating, dry etching, and sputtering, which are processes that are extensively applied in industry. With regard to optical properties, the RNRs with a double refractive index (RNRsD) exhibited a total transmittance that was >90% in the visible range and an optical haze in the range of 42%–50% at a wavelength of 520 nm. Organic light-emitting diodes (OLEDs) with RNRsD, where SiO2 was deposited on the RNRs via radiofrequency sputtering, exhibited an enhancement of 34.5% in the external quantum efficiency compared with OLEDs with the bare substrate. Furthermore, the color variation of the OLEDs with the optimal RNRsD with respect to a change in the viewing angle was improved from color coordinates of Δ(x, y) = (0.032, 0.034) to Δ(x, y) = (0.014, 0.014). Therefore, the proposed film can be used as a scattering layer for enhancing the light extraction and viewing angle of OLEDs by reducing the substrate mode light loss and changing the direction of light. In addition to using a low-temperature fabrication process that does not employ a photomask and a lithographic template, the proposed method is applicable to flexible devices because it uses a polymer and a thin inorganic film.

Nano-bridged nanosphere lithography

We develop nano-bridged nanosphere lithography (NB-NSL), a modification to the widely used conventional nanosphere lithography (NSL). Nano-bridges between polystyrene (PS) spheres of a pristine NSL template are controllably formed in a two-step process: (i) spin-coating of a dilute styrene solution on top of the template, followed by (ii) oxygen plasma etching of the template. We show that the nanobridge dimensions can be precisely tuned by controlling the pre-processing conditions and the plasma etching time. The resulting lithography templates feature control over the shape and size of the apertures, which determine the morphology of the final nano-island arrays after material deposition and template removal. The unique advantage of NB-NSL is that PS particle templates based on a single PS particle diameter can be utilized for the fabrication of a variation of nano-island shapes and sizes, whereas conventional NSL yields only bowtie-shaped nano-islands, with their size being predetermined by the PS particle diameter of the template.

Improvement in light out-coupling efficiency of OLED by using high fill factor parabola curve microlens arrays

Aspheric microlens arrays (MLAs) are introduced on glass substrate to improve the light out-coupling efficiency (LOCE) of organic light-emitting diode (OLED). Geometric ray tracing was employed to simulate the improved effects and optimize the structure parameters of the MLAs pattern. The simulation results show that when the parameters of MLAs as follows, the curved profile is parabola, the base shape is hexagon, the fill factor is 1, the aspect ratio is 0.6, and the material refractive index should be match to that of the substrate of the OLED, which can improve LOCE maximum.Poly-dimethyl-siloxane (PDMS) parabola curve MLAs films ware fabricated by maskless lithography technique and template replication. The experimental results show that the MLAs can improve the LOCE and the trends of the experimental results agree with the simulation results. A maximum increase of 49 % in the coupling efficiency was achieved.

The relationship between hole size and the voltage-driven formation of surface structures in an ITO/liquid crystal polymer/perforated metal electrode system

A device consisting of a multidomain liquid crystal polymer network sandwiched between a continuous electrode and a perforated silver electrode shows strong surface deformations upon application of an electric field between the electrodes. Here, a new method is presented for the preparation of such a device, in which a silver film with circular holes of a well-controlled diameter was made by evaporating silver onto a monolayer of polystyrene spheres. Due to multilayer defects of the polystyrene microparticle lithography template, larger combined holes were present, which provided interesting information about the effect of pore size on the deformation behavior. The results were compared to an electrostatic field distribution, from which the conclusion could be drawn that there is a minimum hole size that allows deformation. This knowledge is important for the development of applications for this kind of device, as the aspect ratio of the deformations is of crucial importance for effects such as switchable wetting and self-cleaning.

Fabrication of Free-Standing Three-Dimensional Block Copolymer Patterns on Substrate

As the importance of three-dimensiona (3D) nano patterns and structures has recently emerged, interest in the study of 3D structures of block copolymers has increased. However, most existing studies on block copolymer 3D patterns on substrates are limited to simple 3D structures such as a multi-layered forms. In this study, we propose an experimental method for realizing free-standing 3D block copolymer patterns on substrates using an e-beam lithographic template and film transfer method. The block copolymer 3D structure formed in wide hole templates are similar to simple multi-layered structures; however, as the width of the hole template become narrower, more complex block copolymer 3D structures are formed in which the upper and lower layer structures are interconnected. Furthermore, we introduce a method to fabricate novel block copolymer structures in which the 2D planar structures are connected to 3D complex structures. Proposed 3D block copolymer fabrication method provides a framework for generation of unconventional 3D structures of block copolymer, which can be useful for next generation 3D devices.

Assessing the accuracy of computer-planned osteotomy guided by stereolithographic template: A methodological framework applied to the mandibular bone harvesting

Intraoral autologous bone grafting represents a preferential choice for alveolar reconstruction prior to dental implant placement. Bone block harvesting guided by a computer-planned lithographic template is a novel and promising technique for optimizing the volume of harvested material, while controlling the osteotomy 3D position with respect to delicate anatomical structures. We provide a quantitative framework to non-invasively estimate the accuracy of this technique. In the proposed framework, the planned osteotomy geometry was compared to the real outcome of the procedure, obtained by segmentation of post-procedural cone beam computed tomography data. The comparison required the rigid registration between pre and post-procedural mandibular models, which was automatically accomplished by minimizing the sum of squared distances via a stochastic multi-trial iterative closest point algorithm. Bone harvesting accuracy was quantified by calculating a set of angular and displacement errors between the planned and real planes which characterized the excision block. The application of the framework to four cases showed its capability to quantify the tolerance associated with computer-guided bone harvesting techniques with submillimetric accuracy (<0.4 mm), within the limits of native image resolution. The validation methodology proved suitable for defining the safety margins of osteotomy surgical planning.

Fabrication of microgrooved scaffolds using near-field electrospinning-assisted lithography (NFEAL)

A simple patterning process combining near-field electrospinning (NFE) and template lithography, called near-field electrospinning-assisted lithography (NFEAL), was developed to prepare polymeric scaffolds with microgroove patterns for potential use in biomedical applications. NFE enabled the deposition of poly (ethylene oxide) (PEO) fibers at a desired position. The diameters of the deposited PEO fibers could be controlled over a range of 0.5–20μm by adjusting the NFE parameters such as voltage, distance, feed rate, and translation speed. The preparation of PEO fibers with 1 and 3μm diameters using NFE, followed by the deposition of polystyrene (PS) and removal of the fiber template, created free-standing PS scaffolds with microgroove patterns. The width of the microgroove was similar to the diameter of the PEO fibers. The depth of the microgroove was also dependent on the dimensions of the PEO fibers; microgrooves of depth 64.49±11.5nm and 216.68±62.9nm were fabricated from PEO fibers of diameters 1 and 3μm, respectively. When C2C12 cells were cultured on the microgrooved scaffolds, they showed enhanced elongation or alignment along the microgrooved scaffolds, especially, for the microgroove (1μm) with a smaller width.

A hierarchical dual-phase photoetching template route to assembling functional layers on Si photoanode with tunable nanostructures for efficient water splitting

Surface functionalization is closely associated with the light harvesting and the charge separation, transfer, and injection efficiencies of water-splitting photoelectrode. Here, a dual-phase photoetching template with hierarchical structure, polyphenylsilsequioxane nanopillars and bicontinuous polyphenylsilsequioxane + polystyrene network layer, is patterned on the Si photoanode via a spinodal phase separation mechanism. Controllably photoetching the polymer template allows us to physically deposit functional layers with tunable nanostructures from net to dispersed dot. As a demonstration, the broken Ni/NiOx net modified Si photoanode exhibits a low onset potential of 0.93 VRHE, a high saturated photocurrent density of 40 mA cm−2 and a stability of 50 h in 1.0 M K-borate under AM1.5 G illumination, resulting from the inhomogeneous barrier height driven efficient charge extraction and low light loss by the dispersed surface modification. The proposed dual-phase lithographic template may open a new avenue to easily assemble functional layers on photoelectrodes for efficient solar energy conversion.

Mechanotunable Surface Lattice Resonances in the Visible Optical Range by Soft Lithography Templates and Directed Self-Assembly.

We demonstrate a novel colloidal self-assembly approach toward obtaining mechanically tunable, cost-efficient, and low-loss plasmonic nanostructures that show pronounced optical anisotropy upon mechanical deformation. Soft lithography and template-assisted colloidal self-assembly are used to fabricate a stretchable periodic square lattice of gold nanoparticles on macroscopic areas. We stress the impact of particle size distribution on the resulting optical properties. To this end, lattices of narrowly distributed particles (∼2% standard deviation in diameter) are compared with those composed of polydisperse ones (∼14% standard deviation). The enhanced particle quality sharpens the collective surface lattice resonances by 40% to achieve a full width at half-maximum as low as 16 nm. This high optical quality approaches the theoretical limit for this system, as revealed by electromagnetic simulations. One hundred stretching cycles demonstrate a reversible transformation from a square to a rectangular lattice, accompanied by polarization-dependent optical properties. On the basis of these findings we envisage the potential applications as strain sensors and mechanically tunable filters.

3D Electrode Design: Additively Manufactured 3D Architectured Nanocrystalline Nickel and Nickel Copper Structures

Imposing a well defined geometrical shape to an electrode is a suitable way for increasing surface area, as well as optimising the mass transfer phenomenon. By combining electrodeposition with two-photon lithography templates, it is possible to create free-form microscale 3D metal architectures with almost complete freedom. This work features nickel and nickel copper, as the electrodeposition of these materials is well studied and they are frequently used catalysts for oxygen and hydrogen evolution reaction (OER and HER). Control over the electrodeposition of nickel and nickel copper into the complex templates was achieved by creating 3D time-dependent electrodeposition simulations to predict the optimal experimental conditions and deposition parameters. The simulations are based on various electrochemical measurements of the two systems, such as rotating disc electrode measurements, cyclic volatammetry and chrono-potentiometry. An additional benefit of the simulations is that it can be used prior to the experiment to determine the feasibility of a given design to be electrodeposited. We successfully deposited various 3D architectured electrode microstructures made of nickel and nickel copper.

Facile fabrication of a large-area and cost-effective PDMS-SERS substrate by sandpaper template-assisted lithography

In this study, a highly reproducible Ag NP loaded polydimethylsiloxane (PDMS) SERS substrate was fabricated by a simple template lithography method.

Charged particle single nanometre manufacturing.

Following a brief historical summary of the way in which electron beam lithography developed out of the scanning electron microscope, three state-of-the-art charged-particle beam nanopatterning technologies are considered. All three have been the subject of a recently completed European Union Project entitled “Single Nanometre Manufacturing: Beyond CMOS”. Scanning helium ion beam lithography has the advantages of virtually zero proximity effect, nanoscale patterning capability and high sensitivity in combination with a novel fullerene resist based on the sub-nanometre C60 molecule. The shot noise-limited minimum linewidth achieved to date is 6 nm. The second technology, focused electron induced processing (FEBIP), uses a nozzle-dispensed precursor gas either to etch or to deposit patterns on the nanometre scale without the need for resist. The process has potential for high throughput enhancement using multiple electron beams and a system employing up to 196 beams is under development based on a commercial SEM platform. Among its potential applications is the manufacture of templates for nanoimprint lithography, NIL. This is also a target application for the third and final charged particle technology, viz. field emission electron scanning probe lithography, FE-eSPL. This has been developed out of scanning tunneling microscopy using lower-energy electrons (tens of electronvolts rather than the tens of kiloelectronvolts of the other techniques). It has the considerable advantage of being employed without the need for a vacuum system, in ambient air and is capable of sub-10 nm patterning using either developable resists or a self-developing mode applicable for many polymeric resists, which is preferred. Like FEBIP it is potentially capable of massive parallelization for applications requiring high throughput.

Utilization of metal–polymer interactions for self-aligned directed self-assembly of device relevant features

Self-aligned strategies are required because today’s feature sizes are beyond the resolution limit of the exposure tools. One self-aligned strategy is directed self-assembly (DSA), where block copolymers (BCP) are thermodynamically driven to self-align with a lithographically defined template with chemical contrast and/or topography. It would be particularly advantageous to also encode existing structures into thermodynamic information, then thermodynamics would cause BCP to self-align to these existing structures rectifying placement error. These existing features could be cut masks, which are required to fabricate devices from line and space arrays, or they could be interconnects. Here, we show a technique, by which metal–polymer interactions can be used in place of polymer–polymer interactions. These metal–polymer interactions, which cannot be adequately described by conventional surface energy comparisons, allow for a true self-aligned process. We begin by classifying process relevant metals including gold, aluminum, copper, tungsten, and cobalt, based upon their thermodynamic interactions with poly(styrene-block-methyl methacrylate). We then created guide patterns using metal and dielectric line space arrays. These patterns, when combined with DSA, allow for lines and space patterns to be self-aligned to any exposed metal features and reduce process constraints on exposure tools. Our process can also be used to align line and space patterns to metal layers during the back end of the line processing. A similar process could also be used to guide contact hole shrink to correct for placement error in the initial lithographic template.

Structural defects in a nanomesh of bulk MoS2 using an anodic aluminum oxide template for photoluminescence efficiency enhancement

Two-dimensional (2D) materials beyond graphene have attracted considerable interest because of the zero bandgap drawbacks of graphene. Transition metal dichalcogenides (TMDs), such as MoS2 and WSe2, are the potential candidates for next 2D materials because atomically thin layers of TMDs exhibit unique and versatile electrical and optical properties. Although bulk TMDs materials have an indirect bandgap, an indirect-to-direct bandgap transition is observed in monolayers of TMDs (MoS2, WSe2, and MoSe2). Optical properties of TMD films can be improved by the introduction of structural defects. For example, large-area spatial tuning of the optical transition of bulk MoS2 films is achieved by using an anodic aluminum oxide (AAO) template to induce structural defects such as edge- and terrace-terminated defects in a nanomesh structure. Strong photoluminescence emission peaks with a band gap of 1.81 eV are observed, possibly because of radiative transition at the defect sites. This work shows that the AAO template lithography method has potential for the production of homogenous large-scale nanomesh structures for practical semiconductor processing applications in future MoS2-based electronic and optical devices.

Directed Self-Assembly of Liquid-Crystalline Molecular Building Blocks for Sub-5 nm Nanopatterning.

The thin-film directed self-assembly of molecular building blocks into oriented nanostructure arrays enables next-generation lithography at the sub-5 nm scale. Currently, the fabrication of inorganic arrays from molecular building blocks is restricted by the limited long-range order and orientation of the materials, as well as suitable methodologies for creating lithographic templates at sub-5 nm dimensions. In recent years, higher-order liquid crystals have emerged as functional thin films for organic electronics, nanoporous membranes, and templated synthesis, which provide opportunities for their use as lithographic templates. By choosing examples from these fields, recent progress toward the design of molecular building blocks is highlighted, with an emphasis on liquid crystals, to access sub-5 nm features, their directed self-assembly into oriented thin films, and, importantly, the fabrication of inorganic arrays. Finally, future challenges regarding sub-5 nm patterning with liquid crystals are discussed.

Self-Assembled Nanofeatures in Complex Three-Dimensional Topographies via Nanoimprint and Block Copolymer Lithography Methods.

Achieving ultrasmall dimensions of materials and retaining high throughput are critical fabrication considerations for nanotechnology use. This article demonstrates an integrated approach for developing isolated sub-20 nm silicon oxide features through combined “top-down” and “bottom-up” methods: nanoimprint lithography (NIL) and block copolymer (BCP) lithography. Although techniques like those demonstrated here have been developed for nanolithographic application in the microelectronics processing industry, similar approaches could be utilized for sensor, fluidic, and optical-based devices. Thus, this article centers on looking at the possibility of generating isolated silica structures on substrates. NIL was used to create intriguing three-dimensional (3-D) polyhedral oligomeric silsesquioxane (POSS) topographical arrays that guided and confined polystyrene-block-poly(dimethylsiloxane) (PS-b-PDMS) BCP nanofeatures in isolated regions. A cylinder forming PS-b-PDMS BCP system was successfully etched using a one-step etching process to create line-space arrays with a period of 35 nm in confined POSS arrays. We highlight large-area (>6 μm) coverage of line-space arrays in 3-D topographies that could potentially be utilized, for example, in nanofluidic systems. Aligned features for directed self-assembly application are also demonstrated. The high-density, confined silicon oxide nanofeatures in soft lithographic templates over macroscopic areas illustrate the advantages of integrating distinct lithographic methods for attaining discrete features in the deep nanoscale regime.