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We have fabricated a microarray of porous silicon Bragg reflectors on a crystalline silicon substrate using a technological process based on standard photolithography and electrochemical anodization of the silicon. The array density is of 170 elements/cm2 and each element has a diameter of 200 μm. The porous silicon structures have been used as platform to immobilize an amino terminated DNA single strand probe. All fabrication steps have been monitored by spectroscopic reflectometry, optical and electron microscopy, and Fourier transform infrared spectroscopy. A label-free detection method has been employed to investigate the hybridization between micromolar DNA probe and its complementary target. Due to fast and low cost production, good reproducibility, and high quality optical features, this platform could be adopted also for other different microarray applications such as proteomics and medical diagnostics. [ABSTRACT FROM AUTHOR]

We present a detailed study of room-temperature current–voltage characteristics of Al–Al2O3–Ag junctions in which the Al electrode was treated by photolithography processing and chemical etching prior to the Al2O3 layer growth. The I–V curves exhibit polarity-dependent irreversible conductance changes and regions of negative differential resistance. These phenomena take place only if the bias voltage exceeds 0.8 V. We discuss a qualitative mechanism for such behavior based on charge accumulation in traps present in the barrier, due to the chemical treatment. [ABSTRACT FROM AUTHOR]

Because techniques such as photolithography for inorganic materials are yet to have their equivalents for organic materials, multispecies patterning of functional organic materials at microscale resolution remains in development. This paper reports on a liquid droplet transfer printing method, that is, used for microscale patterning of multispecies materials. A transfer printing instrument is built with a multidimensional micropositioning stage, thereby enabling the technique to be used to pattern different materials on a single surface. The size range of the transferred liquid droplets can be tuned by manipulating the surface wettability and the gap between the surfaces of the sample and the stamp. The developed technique is used to prepare red–green–blue pixel patterns and microlenses integrated with color filters. [ABSTRACT FROM AUTHOR]

We present a wafer-scale array of resonant coaxial nanoapertures as a practical platform for surface-enhanced infrared absorption spectroscopy (SEIRA). Coaxial nanoapertures with sub-10 nm gaps are fabricated via photolithography, atomic layer deposition of a sacrificial Al2O3 layer to define the nanogaps, and planarization via glancing-angle ion milling. At the zeroth-order Fabry-Pérot resonance condition, our coaxial apertures act as a “zero-mode resonator (ZMR)”, efficiently funneling as much as 34% of incident infrared (IR) light along 10 nm annular gaps. After removing Al2O3 in the gaps and inserting silk protein, we can couple the intense optical fields of the annular nanogap into the vibrational modes of protein molecules. From 7 nm gap ZMR devices coated with a 5 nm thick silk protein film, we observe high-contrast IR absorbance signals drastically suppressing 58% of the transmitted light and infer a strong IR absorption enhancement factor of 104∼105. These single nanometer gap ZMR devices can be mass-produced via batch processing and offer promising routes for broad applications of SEIRA. [ABSTRACT FROM AUTHOR]

A micro-resonator based on porous silicon ridge waveguides is implemented by a large scale standard photolithography process to obtain a low cost and sensitive sensor based on volume detection principle instead of the evanescent one usually used. The porous nature of the ridge waveguides allows the target molecules to be infiltrated in the core and to be detected by direct interaction with the propagated light. Racetrack resonator with radius of 100 μm and a coupling length of 70 μm is optically characterized for the volume detection of different concentrations of glucose. A high sensitivity of 560 nm/RIU is reached with only one micro-resonator and a limit of detection of 8.10 −5 RIU, equivalent to a glucose concentration of 0.7 g/L, is obtained. [ABSTRACT FROM AUTHOR]

In this letter, we present a study of the condensation of exciton-polaritons in large etched pillar structures that exhibit shallow edge trapping. The ≈100 µm 100 x µm pillars were fabricated using photolithography and a BCl3/Cl2 reactive ion etch. A low energy region emerged along the etched edge, with the minima ≈7 µm from the outer edge. The depth of the trap was 0.5-1.5meV relative to the level central region, with the deepest trapping at the corners. We were able to produce a Bose-Einstein condensate in the trap near the edges and corners by pumping non-resonantly in the middle of the pillar. This condensate began as a set of disconnected condensates at various points along the edges but then became a single mono-energetic condensate as the polariton density was increased. Similar edge traps could be used to produce shallow 1D traps along edges or other more complex traps using various etch geometries and scales. [ABSTRACT FROM AUTHOR]

Gratings have been widely accepted as practical and effective deformation carriers/sensors and are commonly used in many deformation measurement methods. Since the deformation measurement sensitivity is directly proportional to the grating frequency, and the measurement accuracy is strongly affected by the grating quality. Thus, it is crucial to prepare an appropriate grating on the specimen surface that is to be measured. Over the past few decades, an increasing number of grating fabrication methods have been developed, including holographic photolithography, electron beam lithography, focused ion beam etching, nanoimprinting, soft lithography, and others. Although substantial literature regarding grating fabrication can be found, a comprehensive review is still necessary to promote the application of these methods. This review introduces the technical details and characteristics of recently developed grating fabrication methods and provides suggestions of which grating fabrication methods to use in correspondence with different deformation measurement methods. Emphasis is placed on the introduction of grating fabrication processes and the quality and applicability of the resulting gratings. [ABSTRACT FROM AUTHOR]

In this paper, we propose a metaheuristic for solving an original scheduling problem with auxiliary resources in a photolithography workshop of a semiconductor plant. The photolithography workshop is often a bottleneck, and improving scheduling decisions in this workshop can help to improve indicators of the whole plant. Two optimization criteria are separately considered: the weighted flow time (to minimize) and the number of products that are processed (to maximize). After stating the problem and giving some properties on the solution space, we show how these properties help us to efficiently solve the problem with the proposed memetic algorithm, which has been implemented and tested on large generated instances. Numerical experiments show that good solutions are obtained within a reasonable computational time. [ABSTRACT FROM AUTHOR]

The effect of ultraviolet light produced ozone and irradiation (UV/ozone) cleaning on the surface properties and interface electrical properties of 4 unit cell (uc) LaAlO3/SrTiO3 samples is examined. A standard photolithography process is used to contaminate the samples which are then cleaned in UV/ozone. Atomic force microscopy measurements show that the photoresist contaminated samples can be cleaned efficiently using this method. The surface roughness of the cleaned samples is comparable to that of the as-grown samples. Furthermore, electrical transport measurements show that the mobility decreases and the sheet carrier density increases for the contaminated samples, which also display indications of an onset to the Kondo effect. By removing the contaminants with UV/ozone cleaning, the mobility and sheet carrier density can be partially restored toward the as-grown values. The mobility is increased by about two times from ≈1000 cm² V-1 s-1 for the contaminated samples to ≈2000 cm² V-1 s-1 for the ozone cleaned ones. [ABSTRACT FROM AUTHOR]

The power of electroforming to faithfully capture and replicate metal features down to the atomic scale has been elegantly exploited to consistently produce OLED deposition masks with high yields. Using a unique combination of photolithography and electroforming, we have produced large area, (10-15) µm thick nickel masks with apertures as small as 14 µm. This manufacturing technology is targeted to provide OLED masks for future generations of ultra-high resolution display manufacturing, possibly down to 10 micron aperture sizes. [ABSTRACT FROM AUTHOR]

Patterning process control has undergone major evolutions over the last few years. Critical dimension, focus, and overlay control require deep insight into process-variability understanding to be properly apprehended. Process setup is a complex engineering challenge. In the era of mid k1 lithography (>0.6), process windows were quite comfortable with respect to tool capabilities, therefore, some sources of variability were, if not ignored, at least considered as negligible. The low k1 patterning (<0.4) era has broken down this concept. For the most advanced nodes, engineers need to consider such a wide set of information that holistic processing is often mentioned as the way to handle the setup of the process and its variability. The main difficulty is to break down process-variability sources in detail and be aware that what could have been formerly negligible has become a very significant contributor requiring control down to a fraction of a nanometer. The scope of this article is to highlight that today, engineers have to zoom deeper into variability. Even though process tools have greatly improved their capabilities, diminishing process windows require more than tool-intrinsic optimization. Process control and variability compensations are major contributors to success. Some examples will be used to explain how complex the situation is and how interlinked processes are today. [ABSTRACT FROM AUTHOR]

In this work, we first report a facile, low-cost and high-throughput method for photolithographical fabrication of microfluidic cloth-based analytical devices (μCADs) by simply using a cotton cloth as a substrate material and employing an inexpensive hydrophobic photoresist laboratory-formulated from commercially available reagents, which allows patterning of reproducible hydrophilic–hydrophobic features in the cloth with well-defined and uniform boundaries. Firstly, we evaluated the wicking properties of cotton cloths by testing the wicking rate in the cloth channel, in combination with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses. It is demonstrated that the wicking properties of the cloth microfluidic channel can be improved by soaking the cloth substrate in 20 wt% NaOH solution and by washing the cloth-based microfluidic patterns with 3 wt% SDS solution. Next, we studied the minimum dimensions achievable for the width of the hydrophobic barriers and hydrophilic channels. The results indicate that the smallest width for a desired hydrophobic barrier is designed to be 100 μm and that for a desired hydrophilic channel is designed to be 500 μm. Finally, the high-throughput μCADs prepared using the developed fabrication technique were demonstrated for colorimetric assays of glucose and protein in artificial urine samples. It has been shown that the photolithographically patterned μCADs have potential for a simple, quantitative colorimetric urine test. The combination of cheap cloth and inexpensive high-throughput photolithography enables the development of new types of low-cost cloth-based microfluidic devices, such as “microzone plates” and “gate arrays”, which provide new methods to perform biochemical assays or control fluid flow. [ABSTRACT FROM AUTHOR]

This work demonstrates an innovative microfabricated air-cooling technology that employs an electrohydrodynamic (EHD) corona discharge (i.e., ionic wind pump) for electronics cooling applications. A single, microfabricated ionic wind pump element consists of two parallel collecting electrodes between which a single emitting tip is positioned. A grid structure on the collector electrodes can enhance the overall heat-transfer coefficient and facilitate an IC compatible batch process. The optimized devices studied exhibit an overall device area of 5.4 mm x 3.6 mm, an emitter-to-collector gap of 0.5 mm. and an emitter curvature radius of ~12.5 p.m. The manufacturing process developed for the device uses glass wafers, a single mask-based photolithography process, and a low-cost copper-based electroplating process. Various design configurations were explored and modeled computationally to investigate their influence on the cooling phenomenon. The single devices provide a high heat-transfer coefficient of up to 3200 Wlrrf K and a coefficient of performance (COP) of up to ~47. The COP was obtained by dividing the heat removal enhancement, ΔQ by the power consumed by the ionic wind pump device. A maximum applied voltage of 1.9kV, which is equivalent to approximately 38 mW of power input, is required for operation, which is significantly lower than the power required for the previously reported devices. Furthermore, the microfabricated single device exhibits a flexible and small form factor, no noise generation, high efficiency, large heat removal over a small dimension and at low power, and high reliability (no moving parts); these are characteristics required by the semiconductor industry for next generation thermal management solutions. [ABSTRACT FROM AUTHOR]

PEDOT:PSS is a robust conductive polymer which is promising in future flexible applications. In order to integrate PEDOT:PSS into various devices, we introduce a simple patterning scheme for PEDOT:PSS. By using a silver interlayer, conventional photolithographic processes can be used. High resolution patterns and ITO-free OLEDs are demonstrated. [ABSTRACT FROM AUTHOR]

The optical diffraction limit has stood for a long time in the way of achieving higher optical resolution in far-field imaging, photolithography, and optical data storage. We present here a simple and original concept for broadband far-field imaging in the visible and ultraviolet range that beats this limit. A finite-sized ultrathin metallic slab is used to encode subwavelength details of the broadband field radiated by an object. This field excites a set of surface plasmon modes on the finite-sized slab that radiates in the far field. A numerical time reversal imaging process is applied to reconstruct the image of the object with a resolution smaller than λ/6 for a gold slab and λ/8 for a silver slab. With these structures, the highest spatial frequencies are no longer limited by the pitch of the array of the subwavelength resonators as in classical metalenses. We show that the resolution depends mainly on the intrinsic properties of the metal but can be slightly controlled by the geometry design of the slab. Thanks to advances in the control of light in space and time, this concept would provide a promising alternative for high-resolution imaging techniques in the visible and ultraviolet range. [ABSTRACT FROM AUTHOR]

Micro-scale pentacene organic field effect transistors (OFETs) were fabricated on a flexible poly(ethylene terephthalate) (PET) substrate. By applying a highly fluorinated developing solvents and its compatible photoresist materials, it has become possible to make the micro-scale patterning for organic devices using standard photolithography without damaging the underlying polymer layers. The flexible pentacene OFETs with 3 μm-sized channel length exhibited stable electrical characteristics under bent configurations and under a large number of repetitive bending cycles. Furthermore, we demonstrated micro-scale organic complementary inverters on a flexible PET substrate using p-type pentacene and n-type copper hexadecafluorophthalocyanine materials. [ABSTRACT FROM AUTHOR]

Abstract: A three-dimensional (3D) graphene incorporated electrochemical sensor was constructed for sensitive enzyme based phenol detection. To form the 3D graphene structure, polydimethylsiloxane (PDMS) micropillars were fabricated in the microchannel by using a conventional photolithography and the surface was modified with 3-aminopropyltriethoxysilane. Then, the negatively charged graphene oxide sheets were electrostatically adsorbed on the PDMS micropillar surface, and reduced in the hydrazine vapor. The resultant 3D graphene film provides a conductive working electrode as well as an enzyme-mediated sensor with a large surface area. After bonded with an electrode patterned glass wafer, the 3D graphene based electrochemical sensor was produced. Using the 3D graphene as a working electrode, an excellent electron transfer property was demonstrated by cyclic voltammetry measurement in an electrolyte solution containing 1mM K3Fe(CN)6 and 0.1M KCl. To utilize the 3D graphene as an enzyme sensor, tyrosinase enzymes were immobilized on the surface of the graphene micropillar, and the target phenol was injected in the microchannel. The enzyme catalytic reaction process was monitored by amperometric responses and the limit of detection for phenol was obtained as 50nM, thereby suggesting that the 3D graphene micropillar structure enhances the enzyme biosensing capability not only by increasing the surface area for enzyme immobilization, but also by the superlative graphene conductivity property. [Copyright &y& Elsevier]

Mesa structural n-type nanocrystalline (NC) FeSi2/p-type Si heterojunctions were fabricated by a liftoff technique combined with photolithography in order to improve the diode performance, particularly to reduce the parasitic capacitance. Their current-voltage characteristics were experimentally studied in the dark and under illumination using a 1.31 μm laser at room temperature. Their junction capacitance density and leakage current density were evidently reduced as compared with those of the normal structural diodes. The mesa diode exhibits a good rectifying action with a rectification ratio of approximately three orders of magnitude at bias voltages of ±1 V. The photodetection was clearly observed owing to the suppression in the dark current. The estimated detectivity is 2.0 × 109 cm√Hz/W at zero bias, which is an order of magnitude larger than that of the normal structural diodes. This should be because the formation of interface states is reduced accompanied by the interface area reduction. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

In this review, we highlight the properties, functions and applications of stimuli-responsive hydrogel patterns in bioanalytical applications. Stimuli-responsive hydrogel patterns can be realized by well-established micro- and nanofabrication technologies such as photolithography and micromolding, and are currently adopted as active components for manipulation of flow and biosamples in microchannel and microarray systems. We overview the properties of stimuli-responsive hydrogel materials and their fabrication methods along with some representative examples in microfluidics and microarrays. [ABSTRACT FROM AUTHOR]

Highlights: [•] We developed a cylinder mold with hybrid-layered patterns. [•] A precise cutting was combined with 3-D photolithography using a flexible mask. [•] The imprint speed was improved by changing a press-force control method. [•] We succeeded in continuous imprinting on a POF at a feeding speed of 20m/min. [Copyright &y& Elsevier]

Nozzles with micro-scale orifices drive high-resolution printing techniques for generating micro- to nano-scale droplets/lines. This paper presents the fabrication and application of Si-nozzles in mechano-electrospinning (MES). The fabrication process mainly consists of photolithography, Au deposition, inductively coupled plasma, and polydimethylsiloxane encapsulation. The 6 wt% polyethylene oxide solution is adopted to study the electrospinning behaviour and the relations between fibre diameter and process parameters in MES. A fibre grid with 250μm spacing is able to be direct written, and the diameters are less than 3μm. To improve the printing efficiency, positioning accuracy and flexibility, a rotatable multi-nozzle is adopted. The distance between parallel lines reduces sharply from 4.927 to 0.308mm with the rotating angle increasing from 0° to 87°, and the fibre grids with tunable distance are achieved. This method paves the way for fabrication of addressable Si-nozzle array in parallel MES direct writing. [ABSTRACT FROM AUTHOR]

In the paper, sub-femtoliter droplets were easily produced by droplet splitting at a simple T-junction with orifice, which did not need expensive equipments, complex photolithography skill, or high energy input. The volume of the daughter droplet was not limited by channel size but controlled by channel geometry and fluidic characteristic. Moreover, single bead sampling and bead quantification in different orders of magnitude of droplet volumes were investigated. The droplets split at our T-junction chip had small volume and monodispersed size and could be produced efficiently, orderly, and controllably. [ABSTRACT FROM AUTHOR]

Scalable fabrication of high quality graphene devices is highly desired and important for the practical applications of graphene material. Graphene devices are massively fabricated on SiO2/Si substrate through an efficient process, which combines large scaled growth of monolayer graphene on Pt foil, modified bubbling transfer and photolithography-based device fabrication. These graphene devices present yield up to 86% (70 out of 81), field-effect mobility around 2500 cm2 V-1 S-1 and Dirac point voltage near to 0 V, as well as a narrow performance metrics distribution. In addition, as-fabricated graphene Hall elements through this process exhibit high current sensitivity typically up to 1200 V/AT. [ABSTRACT FROM AUTHOR]

Abstract: In the paper, the characteristic of imaging with digital micro-mirror device (DMD) illuminated by a partially coherent light is discussed using Abbe''s method. When a mask is sampled by DMD, the intensity in the substrate is modulated by sinc function and cut off by pupil function, according to oblique illumination theory and Fourier transform property of exponential function, a fast partially coherent imaging algorithm for DMD-based dynamic projection photolithography is proposed to combine Hopkins''s method with Abbe''s method. In the algorithm, the transmission cross coefficient (TCC) matrix of DMD projection photolithography is constructed as two-matrix multiplication according to illuminate source points. The new development presented in this paper utilizes matrix multiplication technique to speed up the computation of TCC matrix by tenfold on an average, which is beneficial to real time mask shift and mask optimization in DMD-based gray-tone photolithography. [Copyright &y& Elsevier]

This paper introduces the development of a double-sided micro lens array (DSMLA) for application in micro laser projectors. For commercial mass production, it is necessary to investigate the concurrent engineering of optical design, mold fabrication, and plastic injection molding at once. This experiment based the design of the micro lens array on the scalar diffraction theory. The proposed DSMLA can simultaneously shape red, green, and blue laser beams into a uniform projection pattern. An ultra precision diamond turning machine using a slow tool servo method fabricated the mold. The study considered optical design constraints from the feedback of mold fabrication and plastic injection molding, measuring and comparing fabricated samples with calculated results. Experimental results show that the fabricated DSMLAs achieve the desired function and application feasibility for micro laser projectors. [ABSTRACT FROM AUTHOR]

We describe the design of micropatterned surfaces for single cell studies, based on thermoresponsive polymer brushes. We show that brushes made of poly(N-isopropylacrylamide) grafted at high surface density display excellent protein and cell anti-adhesive properties. Such brushes are readily patterned at the micron scale via deep UV photolithography. A proper choice of the adhesive pattern shapes, combined with the temperature-dependent swelling properties of PNIPAM, allow us to use the polymer brush as a microactuator which induces cell detachment when the temperature is reduced below 32°C. [ABSTRACT FROM AUTHOR]

We present a simple size reduction technique for fabricating 400 nm zinc oxide (ZnO) architectures using a silicon master containing only microscale architectures. In this approach, the overall fabrication, from the master to the molds and the final ZnO architectures, features cost-effective UV photolithography, instead of electron beam lithography or deep-UV photolithography. A photosensitive Zn-containing sol-gel precursor was used to imprint architectures by direct UV-assisted nanoimprint lithography (UV-NIL). The resulting Zn-containing architectures were then converted to ZnO architectures with reduced feature sizes by thermal annealing at 400 °C for 1 h. The imprinted and annealed ZnO architectures were also used as new masters for the size reduction technique. ZnO pillars of 400 nm diameter were obtained from a silicon master with pillars of 1000 nm diameter by simply repeating the size reduction technique. The photosensitivity and contrast of the Zn-containing precursor were measured as 6.5 J cm-2 and 16.5, respectively. Interesting complex ZnO patterns, with both microscale pillars and nanoscale holes, were demonstrated by the combination of dose-controlled UV exposure and a two-step UV-NIL. [ABSTRACT FROM AUTHOR]

This paper introduces a new design technique for a capacitive gap-coupled bandpass filter (BPF) using non-uniform arbitrary image impedances. Based on the proposed BPF equivalent circuit model, the filter's design equations are derived, and they are validated from comparisons of the calculated and simulated results. For this theoretical verification, the BPF using non-uniform arbitrary image impedances is designed using the specifications of: center frequency (fc) = 5:8 GHz, fractional bandwidth (FBW) = 3:5%, and filter stage (N) = 3. The calculated and simulated results of the designed filter show good agreement. The BPF using the proposed design method could provide an advantage that one can arbitrarily determine two different image impedances, which ultimately affects the BPF's coupling gaps and line widths. This could result in suitable filter dimensions, i.e., gaps and line width, for a conventional low resolution photolithography fabrication although a low or high dielectric constant substrate is used for the design. [ABSTRACT FROM AUTHOR]

Modern maskless photolithography systems based on using spatial light modulators are analyzed in this review. Principles of construction, examples of implementation of systems, as well as factors limiting their spatial resolution are discussed. [ABSTRACT FROM AUTHOR]

This paper reports a facile fabrication technique for micro-patterned two-dimensional (2D) nanorod and nanohole arrays. This technique is based on a combination of two simple and scalable processes: photolithography for micro-patterns and nanosphere lithography (NSL) for nano-patterns. Mixed patterns, such as micro-scale line patterned 2D SiO2 nanoarrays, can be routinely fabricated over a quartz substrate owing to the high reproducibility of this simple method. In micro-patterned 2D nanoarrays, the structural dimensions of micro-patterns can be controlled by general optimization of photolithography techniques; structural dimensions of nano-patterns can be controlled with the NSL technique. We demonstrate micro-patterned fluorescence images of SrGa2S4:Eu2+ thin-film phosphors (TFPs) by depositing TFPs on micro-patterned 2D SiO2 photonic crystal (PC) nanoarrays using rf-magnetron sputtering technique. It is expected that photolithography-assisted NSL will be incorporated easily in the fabrication of micro-patterned PC for the various photonic or optoelectronic devices. [ABSTRACT FROM AUTHOR]

Recent advances in materials science have made it possible to perform photolithography at the nanoscale using visible light. One approach to visible-light nanolithography (resolution augmentation through photo-induced deactivation) uses a negative-tone photoresist incorporating a radical photoinitiator that can be excited by two-photon absorption. With subsequent absorption of light, the photoinitiator can also be deactivated before polymerization occurs. This deactivation step can therefore be used for spatial limitation of photopatterning. In previous work, continuous-wave light was used for the deactivation step in such photoresists. Here we identify three broad classes of photoinitiators for which deactivation is efficient enough to be accomplished by the ultrafast excitation pulses themselves. The remarkable properties of these initiators result in the inverse scaling of lithographic feature size with exposure time. By combining different photoinitiators it is further possible to create a photoresist for which the resolution is independent of exposure over a broad range of fabrication speeds. [ABSTRACT FROM AUTHOR]

The click reaction paradigm is focused on the development and implementation of reactions that are simple to perform while being robust and providing exquisite control of the reaction and its products. Arguably the most prolific and powerful of these reactions, the copper-catalysed alkyne-azide reaction (CuAAC) is highly efficient and ubiquitous in an ever increasing number of synthetic methodologies and applications, including bioconjugation, labelling, surface functionalization, dendrimer synthesis, polymer synthesis and polymer modification. Unfortunately, as the Cu(I) catalyst is typically generated by the chemical reduction of Cu(II) to Cu(I), or added as a Cu(I) salt, temporal and spatial control of the CuAAC reaction is not readily achieved. Here, we demonstrate catalysis of the CuAAC reaction via the photochemical reduction of Cu(II) to Cu(I), affording comprehensive spatial and temporal control of the CuAAC reaction using standard photolithographic techniques. Results reveal the diverse capability of this technique in small molecule synthesis, patterned material fabrication and patterned chemical modification. [ABSTRACT FROM AUTHOR]

This paper describes a method for fabricating deep Si trenches with only a wet chemical etching process. A typical photolithography process was used to define the etching area. Aqueous HF/AgNO3 and HF/H2O2 solutions were applied to etch silicon nanowire (SiNW) structures in the selected domains. In the former case, a high selectivity between the bare Si surface and photoresist-covered Si surface can be achieved. The SiNWs with a monolithic (100) direction can be etched in the selected domain. However, additional (010)- and (001)-oriented etchings were observed on the trench sidewall and wafer surface in the latter case. En addition, deep and highly anisotropic trenches were achieved by removing the SiNWs. The Si wafer was immersed in a concentrated aqueous HF/H2O2 solution. A porous Structure was formed in the vicinity of Ag nanoparticles, suggesting that one should remove S1NWs completely to achieve deep anisotropic trenches. This method exhibits high anisotropy and is capable of etching deep Si trenches with depths of about 50 μm without an additional etching mask. It effectively minimizes instrument costs and reveals the potential of large-area fabrication. [ABSTRACT FROM AUTHOR]

Two different polyazomethine-type conjugated polymers, poly(phenoxiazine-3,3'-dihydroxybensidine)(PZ-DHB) and poly(phenoxiazine-2,4-diamino-6-hydroxypyrimidine)(PZ-DHP) containing phenothiazine moiety and azomethine linkage in the main chain were synthesized by Schiff-base polycondensation reactions. The polymer poly(PZ-DHB) was converted to the photosensitive type, through Mitsunobu reaction by incorporation of a photocrosslinkable group, hydroxyhexyloxystyryl-2-pyridine(2-HHSP) into the polymer side chains. The photosensitive conjugated polymer, poly(PZ-DHB)-PS, exhibited both strong fluorescence emission at 555 nm and good patterning property in the standard photolithographic processes. [ABSTRACT FROM AUTHOR]

A method using scatterometry for simultaneous focus and critical dimension (CD) control method has been developed. Our focus and CD measurement method uses a five-layer scatterometry model and provides stable focus measurement when the exposure dose fluctuates. We utilize this feature and consider applying it to the response surface methodology model for focus and CD control. This control optimizes focus and calculates the correct dose allowing for the focus effect. We have confirmed that this method controls photoresist shape accurately and reduces the CD variation for 65 nm devices by 80%. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we describe the development of microcontact printing stamps from photopatternable silicone. The photopatternability of this material enables convenient and fast stamp fabrication, and allows rapid patterning of substrates for culturing biological cells. Microcontact printing stamps made of the photopatternable silicone with linewidths as small as 2μm were fabricated and reliable cell patterning results were obtained by optimizing the stamping process. An optimal stamp surface was obtained by optimizing the photolithographic process. Our successful demonstration of patterning cells using the photopatternable silicone stamps establishes this alternative approach for fabricating microcontact printing stamps. [Copyright &y& Elsevier]

Electrical characteristics of devices depend on the line edge roughness (LER). LER contributes to the off-state leakage budget and short-channel effect. Therefore, it has to be controlled during the lithography step since it strongly impacts the final component’s roughness. This work aims at the characterization of LER dependence on the beam acceleration voltage. Usually publications consider many lithography parameters that can influence LER. Different resists were exposed to beam acceleration voltage from 5 to 50 kV. Thus, only two parameters that influence LER varied during experiments for a given resist: the exposure dose (i.e., shot noise) and the spot size. Then, simulations were carried out with those parameter variations. The impact of other LER contributors was considered as constant. Comparison between model and experimental results allows one to link resist sensitivity, exposure time, and LER. [ABSTRACT FROM AUTHOR]

The authors report on a hybrid lithography process that integrates electron beam lithography (EBL) and optical photolithography. To maximize resolution and density, the EBL exposure is performed using a hydrogen silsesquioxane-based resist, while the photolithographic exposure is performed using standard positive or negative tone 248 nm photoresists. Both exposures take place on a common underlayer consisting of an antireflective coating (ARC). During pattern transfer into the ARC layer, a composite image of the two lithographic exposures is formed creating a robust and versatile etch mask for further pattern transfer into the substrate. They demonstrate the utility of this technique by using it to pattern the active, gate, and wiring levels of complementary metal oxide semiconductor devices and circuits consisting of trigated Fin-based field effect transistors. These devices have a minimum active area pitch of 50 nm, minimum gate pitch of 90 nm, and achieve densities suitable for 15 nm node static random access memory cells. Details of the exposure process and device fabrication are discussed along with electrical results from the resulting devices and circuits built using this technique. [ABSTRACT FROM AUTHOR]

Rapid progress on nanodevices points to a promising direction for future circuit design. However, since nanofabrication techniques are not yet mature, implementation of nanocircuits, at least on a large scale, in the near future is infeasible. To ease fabrication and overcome the problem of high defect levels in nanotechnology, hybrid nano/CMOS reconfigurable architectures are attractive choices. Moreover, if the current photolithography fabrication process can be used to manufacture the hybrid chips, the benefits of nanotechnologies can be realized today. Traditional reconfigurable architectures can only support partial or coarse-grain runtime reconfiguration due to their limited on-chip storage and long off-chip reconfiguration latency. Recent progress on nano Random Access Memories (RAMs), such as carbon nanotube-based RAM (NRAM), Phase-Change Memory (PCM), magnetoresistive RAM (MRAM), etc., provides us with a chance to realize on-chip fine-grain runtime reconfiguration. These nano RAMs have good compatibility with the current fabrication process. By utilizing them in the hybrid design, we can take advantage of both CMOS and nanotechnology, and greatly improve the logic density, resource utilization, and performance of our design. In this article, we propose a high-performance reconfigurable architecture, called NATURE, that utilizes CMOS logic and nano RAMs. An automatic design flow for NATURE is presented in Part II of the article. In NATURE, the highly dense nonvolatile nano RAMs are distributed throughout the chip to allow large embedded on-chip configuration storage, which enables fast reading and hence supports fine-grain runtime reconfiguration and temporal logic folding of a circuit before being mapped to the architecture. Temporal logic folding can significantly increase the logic density of NATURE (by over an order of magnitude for large circuits) while remaining competitive in performance and power consumption. For ease of exposition, we use NRAMs to illustrate various concepts in this article due to the excellent properties of NRAMs. However, other nano RAMs can also be used instead. Experimental results based on NRAMs establish the efficacy of NATURE. [ABSTRACT FROM AUTHOR]

Based on a contact process, the ultraviolet (UV) nanoimprint process can overcome the linewidth limit of conventional photolithography caused by the diffraction effect. However, the contact between the mold and resist may introduce various defects to the two components. Some researchers have investigated the defects that emerge in the imprint process, such as particle contamination and curing shrinkage of the resist. However, the curing process of the resist itself should be studied because the curable resist is the carrier of the pattern transfer and the replication is accomplished by its shape remodeling. In this article, the authors focus on the effects of exposure time on the defects and demolding force in the soft UV imprint process. The replications are made by a soft polydimethylsiloxane mold under the same process parameters except that the curing time is different. Moreover, the curing degree of the resist and the value of the demolding force under various curing doses are measured. A mechanical model is established to analyze the behavior of the resist, which transitions from a liquid to solid stage by stage, and will help the authors to understand the above effects. By analyzing the relationships among the model of the resist, curing degree, demolding force, and resultant defects in the experiments, they propose a curing window, within which the curing time in the imprint process helps to remove defects in the shaped patterns and soft mold. Finally, using the optimized curing time, the best replicated patterns with 100 nm features are obtained. [ABSTRACT FROM AUTHOR]

We describe a method for printing electrospun nanofibers from a collector onto another substrate. The electrospinning collector that we used is made of a thin layer of polydimethylsiloxane (PDMS) on glass with or without patterned electrodes, allowing the fabrication of either aligned or randomly deposited nanofibers. Afterwards, the electrospun fibers are printed onto a glass substrate, and such a process can be repeatedly used to obtain multilayer fibers with a good reproducibility. We also show a postprocessing method for the pattern formation of electrospun nanofibers by using standard photolithography and reactive ion etching techniques, thereby providing a way of fabricating microarrays of single fibers or distributed fiber matrices. [ABSTRACT FROM AUTHOR]

A fabrication process of 316-L stainless steel microcomponents and characterisation of their surface roughness and porosity is presented. The fabrication process is divided into two parts. In the first part, SU-8 master moulds and their negative replicas from soft moulds are fabricated using photolithography and soft moulding techniques, respectively. The second part includes preparing stainless steel slurry using super fine stainless steel powder and binder, filling the soft moulds, obtaining the green parts, de-binding and sintering to the final parts. The resultant microparts reflect the same quality as the SU-8 master moulds. The surface roughness and porosity of the microparts are investigated using stereo imaging technique and X-ray microtomography, respectively. The average surface roughness Ra measures 132.2 nm and the overall porosity is found to be 4.5%. [ABSTRACT FROM AUTHOR]

Compliant free-standing structures can be used as chip-to-substrate interconnects. Such "compliant interconnects" are a potential solution to the requirements that will be imposed on chip-to-substrate interconnects over the next decade. However, cost of implementation and electrical performance limit compliant interconnects. In our previous work, we have proposed a new compliant interconnect technology called FlexConnect to address these concerns with compliant interconnects. An innovative cost-effective MEMS-based fabrication process is used to fabricate these compliant interconnects. Sequential lithography and electroplating processes with up to two masking steps are utilized. Utilizing the proposed fabrication process, in this paper, FlexConnects are realized at a 100-μm pitch. High-frequency modeling of the electrical parasitics of the interconnect is performed. Through finite-element-based models, the advantage of using multiple electrical paths as part of the interconnect design is shown from a thermomechanical reliability perspective. Finally, taking advantage of the MEMS-based photolithographic fabrication process, a heterogeneous combination of FlexConnects and column interconnects is proposed. This approach is shown to be an additional avenue to attain improved electrical performance without compromising mechanical performance. [ABSTRACT FROM AUTHOR]

Glass hot-embossing is one of essential techniques for the development of high-performance optical, bio, and chemical micro electromechanical system (MEMS) devices. This method is convenient, does not require routine access to clean rooms and photolithographic equipment, and can be used to produce multiple copies of a quartz mold as well as a MEMS component. In this study, quartz molds were prepared by hot-embossing with the glassy carbon (GC) masters, and they were applied to the hot-emboss of borosilicate glasses. The GC masters were prepared by dicing and focused ion beam (FIB) milling techniques. Additionally, the surfaces of the embossed quartz molds were coated with molybdenum barrier layers before embossing borosilicate glasses. As a result, micro-hot-embossed structures could be developed in borosilicate glasses with high fidelity by hot embossing with quartz molds. [ABSTRACT FROM AUTHOR]

Abstract: Patternable nanoporous silica thin films with pore sizes on multiple length scales are fabricated using preformed block copolymer/homopolymer blend films as templates. Previous work by Tirumala et al. [V.R. Tirumala, R.A. Pai, S. Agarwal, J.J. Testa, G. Bhatnagar, A.H. Romang, C. Chandler, B.P. Gorman, R.L. Jones, E.K. Lin, J.J. Watkins, Adv. Mater. 18 (8) (2008) 1603] has demonstrated that hydrogen bonding between an amphiphilic copolymer and a homopolymer leads to significant enhancements in the long range order of the template self assembly. However if the copolymer template is simply changed from Pluronic F127 to Brij78, a well ordered template is no longer always obtained; the blend phase separates with apparent selective partitioning of the photoacid generator (PAG) at the interface of the polymer phases. UV exposure selectively generates a photoacid, which is utilized to catalyze tetraethylorthosilicate (TEOS) condensation. The large disparity in diffusivity of the photoacid between the glassy poly(hydroxystyrene) (PHOSt) and rubbery Brij78 phases results in selective templating of the Brij mesostructure and limited reaction into the PHOSt. Calcination yields relatively monodisperse mesopores from the Brij phase and macropores from the PHOSt phase. Simple variations in processing parameters allow the macropore morphology to be tuned to create high surface area materials with structures on the order of 1 nm, 100 nm and μms from self assembly, phase separation and lithographic patterning respectively. [Copyright &y& Elsevier]

Photolithographically-defined patterned arrays of Co-rich Co-Pt permanent magnets with thicknesses up to 10 µm were fabricated by aqueous electrodeposition. These micromagnets exhibited strong perpendicular magnetic performance while being deposited at low temperatures (65° C) and without the need for post-deposition annealing. Co-Pt magnet arrays grown 10-µm thick on textured Cu (111) seed layers on Si (110) substrates exhibited coercivities of 330 kA/m (4.1 kOe) and energy products 69 kJ/m³. Additionally, magnets deposited 8-µm thick on untextured Cu seed layers on standard Si (100) substrates exhibited coercivities up to 260 kA/m (3.3 kOe) and energy products up to 27 kJ/m³. The high magnetic performance and process integrability of these permanent magnet arrays make them well suited for the development of magnetic microelectromechanical systems (MEMS). [ABSTRACT FROM AUTHOR]

Because of the ever-decreasing feature size in modern photolithography, the complexity of semiconductor patterns continues to increase dramatically, resulting in prolonged tape-out times. The most time-consuming process in the tape-out flow is model-based optical proximity correction (OPC), which employs two components: a process model and a recipe. The process model predicts how the manufacturing process will behave at a given location on a wafer, whereas the recipe controls how the model information is used to modify the pattern. The recipe uses the model multiple times for each fraction of a polygon in a semiconductor device pattern, resulting in hundreds of billions of complex and time-consuming calculations. To analyze a design-team-drawn device pattern for semiconductor manufacturability, these tape-out calculations need to be performed. This study is designed to reduce the semiconductor pattern manufacturing analysis time by creating an OPC recipe simulation in the process model for use in rapid analysis and filtering of the drawn semiconductor design. In this study, the authors introduce a method of calculating the OPC effect by modifying the optical model, which is equivalent to transferring the OPC effect into the process model. [ABSTRACT FROM AUTHOR]

Abstract  Single crystal beams made by (111)-oriented Si micromachining are usually anchored to the substrate directly. It is difficult to use the beams as resonators, since they are electrically connected to the substrate. This paper presents a modified process to fabricate single crystal nano beams which are electrically isolated from the substrate. In this process, the single crystal nano beams are fully released from the substrate and mechanically supported by metal wires, which also serve as electrical connections. The metal wires are much stiffer than the beams and do not degrade the mechanical properties of the beam according to simulations. The length and width of the beams are determined by photolithography. The thickness of the beam and the gap between the beam and the substrate are determined by the dry etching and KOH etching processes. The influence of KOH etching on the beam thickness is documented through ongoing experiments. At present, the double clamped beams and the cantilever beams have been fabricated. The thinnest beam to date was measured to be 47 nm. The resistance between the beam and the substrate was measured to be 214GΩ, while the resistance of a 147 nm-thick beam was measured to be 816 Ω. The surface roughness of the (111) plane is also discussed. The RMS surface roughness of the nano beam was measured to be 1.08 nm in an area of 5 μm × 5 μm, which was etched with 45%wt. KOH at 50°C. [ABSTRACT FROM AUTHOR]