Design of Microstructure Parameters on a Small Multi-Throttle Aerostatic Guideway in Photolithography

A compact multi-throttle aerostatic guideway is the preferred structure for high precision and acceleration motion in the variable-slit system(VS)of photolithography.The presence of microstructure,such as recesses and grooves,on the guideway working surface has been found to improve the loading performance.Nevertheless,the effects on the guideway performance of changing the microstructure on the micron level are not yet clear.The mesh adaptation method,which was proposed by the authors,is employed in this paper to quantitatively study the influences of four microstructure parameters.The effect of tuning these parameters on the loading performance is revealed.The level of impact determines the proposed design process of the parameters.The characteristic feature of the proposed design process is that the working points of carrying capacity,stiffness,and rotational stiffness are unified under twoway adjusting by means of recess parameters.According to the proposed design process and tuning method,the restriction of supply pressure is lifted to a certain extent and the mutual tradeoff among the loading performances is relieved.The experimental results show that the rotational stiffness of the designed guideway,based on the tuned parameters,reached 2.14×10^(4) Nmrad1 and increased by 69.8%.In a scanning test of the applied VS on argon fluoride laser(ArF)photolithography,the average scanning acceleration reached 67.5 m·s^(-2),meeting the design specification.

Regulation of actin cytoskeleton via photolithographic micropatterning

Actin cytoskeleton plays crucial roles in various cellular functions.Extracellular matrix(ECM)can modulate cell morphology by remodeling the internal cytoskeleton.To define how geometry of ECM regulates the organization of actin cytoskeleton,we plated individual NIH 3T3 cells on micropatterned substrates with distinct shapes and sizes.It was found that the stress fibers could form along the nonadhesive edges of T-shaped pattern,but were absent from the opening edge of V-shaped pattern,indicating that the organization of actin cytoskeleton was dependent on the mechanical environment.Furthermore,a secondary actin ring was observed on 50μm circular pattern while did not appear on 30μm and 40μm pattern,showing a size-dependent organization of actin cytoskeleton.Finally,osteoblasts,MDCK and A549 cells exhibited distinct organization of actin cytoskeleton on T-shaped pattern,suggesting a cell-type specificity in arrangement of actin cytoskeleton.Together,our findings brought novel insight into the organization of actin cytoskeleton on micropatterned environments.

Moth-eye Structured Polydimethylsiloxane Films for High-Efficiency Perovskite Solar Cells

Large-area polydimethylsiloxane(PDMS)films with variably sized moth-eye structures were fabricated to improve the efficiency of perovskite solar cells.An approach that incorporated photolithography,bilayer PDMS deposition and replication was used in the fabrication process.By simply attaching the moth-eye PDMS films to the transparent substrates of perovskite solar cells,the optical properties of the devices could be tuned by changing the size of the moth-eye structures.The device with 300-nm moth-eye PDMS films greatly enhanced power conversion efficiency of ~21 % due to the antireflective effect of the moth-eye structure.Furthermore,beautiful coloration was observed on the 1000-nm moth-eye PDMS films through optical interference caused by the diffraction grating effect.Our results imply that moth-eye PDMS films can greatly enhance the efficiency of perovskite solar cells and building-integrated photovoltaics.

Ultrahigh-rate and high-frequency MXene micro-supercapacitors for kHz AC line-filtering

Harnessing energy from the environment promotes the rapid development of micro-power generators and relevant power management modules of alternating current (AC) line-filtering to obtain a stabilized direct current (DC) output for storage and use. Micro-supercapacitors (MSCs) with miniaturized volume and high-frequency response are regarded as a critical component in filtering circuits for microscale power conversion. Here, we reported the fabrication of the wafer-sized planar MSCs (M-MSCs) based on 2D Ti_(2)C_(2)T_(6) MXene using a photolithography technique. The M-MSCs exhibited an areal capacitance of 153 μF cm^(-2) and a frequency characteristic (f_(0)) of 5.6 k Hz in aqueous electrolyte. Moreover, by employing suitable ionic liquid as electrolyte, the voltage window was expanded to 2 V and the f_(0) could be pushed to 6.6 k Hz relying on the electrical double-layer mechanism and lower adsorption energy while maintaining quasi-rectangular cyclic voltammogram curves at 5000 V s^(-1). Furthermore, the integrated MSCs pack was constructed and exhibited excellent rectifying ability by filtering various highfrequency 5000 Hz AC signals with different waveforms into stable DC outputs. Such ultrahigh-rate and high-voltage M-MSCs module for k Hz AC line-filtering would be potentially integrated with customizable electronics to realize on-chip rectifiers in high-density integrated circuit.

Selection of DBO measurement wavelength for bottom mark asymmetry based on FDTD method

A physical model for simulating overlay metrology employing diffraction based overlay(DBO)principles is built.It can help to optimize the metrology wavelength selection in DBO.Simulation result of DBO metrology with a model based on the finite-difference time-domain(FDTD)method is presented.A common case(bottom mark asymmetry)in which error signals are always induced in DBO measurement due to the process imperfection were discussed.The overlay sensitivity of the DBO measurement across the visible illumination spectrum has been performed and compared.After adjusting the model parameters compatible with the actual measurement conditions,the metrology wavelengths which provide the accuracy and robustness of DBO measurement can be optimized.

The Variables and Invariants in the Evolution of Logic Optical Lithography Process

Photolithography has been a major enabler for the continuous shrink of the semiconductor manufacturing design rules.Throughout the years of the development of the photolithography,many new technologies have been invented and successfully implemented,such as image projection lithography,chemically amplified photoresist,phase shifting mask,optical proximity modeling and correction,etc.From 0.25μm technology to the current 7 nm technology,the linewidth has been shrunk from 250 nm to about 20 nm,or 12.5 times.Although imaging resolution is proportional to the illumination wavelength,with the new technologies,the wavelength has only been shrunk from 248 nm to 134.7 nm(193 nm immersion in water),less than 2 times.Would it mean that the imaging performance has been continuously declining?Or we have yet fully utilized the potential of the photolithography technology?In this paper,we will present a study on the key parameters and process window performance of the image projection photolithography from 0.25μm node to the current 7 nm node.

Acidic Polyester Imides as Thermally Stable Binder Polymers for Negative-Tone Black Photoresist

Polyimides are well-known for their high chemical inertness and thermal stability. However, it is usually challenging to synthesize UV-curable polyimides since the imidization reaction requires such harsh conditions that acrylate type double bonds cannot withstand. In this work, synthetic methods are developed to obtain polyester-imide type binder polymers with high thermal stability, high compatibility with the other components of the black photoresist, and fine photolithographic patterning property for the negative-tone black photoresist. The syntheses of diimide-diacid or diimide-diol intermediates for the polyesterification with dianhydride gave polyester imides which meets this requirement. The photolithographic tests have shown that the patterning of the micron-sized PDL of the organic light emitting diode (OLED) panel could be obtained. This work will interest the researchers working on the design and optimization of thermally stable binder polymers.

Black Photoresist for Patterning Pixel Define Layer of Organic Light Emitting Diode with Polyimide as Thermal Stabilizer

In order to improve the visibility for outside use of organic light emitting diodes (OLEDs), the polarized film and black matrix pattern have been used in the small and medium sized OLEDs;however, these cause problem of reducing the emission efficiency of OLED. Changing the color of pixel define layer (PDL) from brown to black is an important point for improving the efficiency and visibility of OLEDs. In this work we studied the photoresist material containing black pigment and the photolithographic process for patterning of black PDL on OLEDs. The black PDL patterns made with our synthesized polyimides as thermal stabilizer were found to give high thermal stability over 300°C.

Fabrication of multi-level 3-dimension microstructures by phase inversion process

One process based on phase inversion of fillers in microstructures for the fabrication of multi-level three-dimensional(3-D) microstructures is described using SU-8, a kind of epoxy photoresist, as the model constructing materials. This process is depicted by use of the routine photolithography technique to construct the top layer of 3-D microstructures on the bottom layer of 3-D microstructures layer by layer. This process makes it possible to fabricate multi-level 3-D microstructures with connectors at desired locations, and to seal long span microstructures(e.g. very shallow channels with depth less than 50 μm and width more than 300 μm) without blockage. In addition, this process can provide a sealing layer by the solidification of a liquid polymer layer, which can be as strong as the bulk constructing materials for microstructures due to a complete contact and cross-linking between the sealing layer and the patterned layers. The hydrodynamic testing indicates that this kind of sealing and interconnection can endure a static pressure of more than 10 MPa overnight and a hydrodynamic pressure drop of about 5.3 MPa for more than 8 hours by pumping the tetrahydrofuran solution through a 60 μm wide micro-channels.

Large-scale photonic crystals with inserted defects and their optical properties

Deliberately introducing defects into photonic crystals is an important way to functionalize the photonic crystals. We prepare a special large-scale three-dimensional （3D） photonic crystal （PC） with designed defects by an easy and low-cost method. The defect layer consists of photoresist strips or air-core strips. Field emission scanning electron microscopy （FESEM） shows that the 3D PC is of good quality and the defect layer is uniform. Different defect states shown in the ultraviolet-visible spectra are induced by the photoresist strip layer and air-core strip layer. The special large-scale 3D PC can be tested for integrated optical circuits, and the defects can act as optical waveguides.

Electro-and photochemical studies of gold (Ⅲ) bromide towards a novel laser-based method of gold patterning

In this report, we demonstrate a novel technique for the microscopic patterning of gold by combining the photoreduction of Au^(Ⅲ)Br_(2)^(-)to Au^(Ⅰ)Br_(2)^(-)and the electrochemical reduction of Au^(Ⅰ)Br_(2)^(-)to elemental gold in a single step within solution. While mask-based methods have been the norm for electroplating, the adoption of direct laser writing for flexible, real-time patterning has not been widespread. Through irradiation using a 405 nm laser and applying a voltage corresponding to a selective potential window specific to Au^(Ⅰ)Br_(2)^(-), we have shown that we can locally deposit elemental gold at the focal point of the laser. In addition to demonstrating the feasibility of the technique, we have collected data on the kinetics of the photoreduction reaction in ethanol and have deduced its rate law. We have confirmed the selective deposition of Au^(Ⅰ)Br_(2)^(-) within a potential window through controlled potential electrolysis experiments and through direct measurement on a quartz crystal microbalance. Finally, we have verified local deposition through scanning electron microscopy.

Optical Properties of Aligned Nematic Liquid Crystals in Electric Field

In this study, the optical transmittance of aligned nematic liquid crystals (ANLCs) was investigated in terms of temperature variations through electrooptic effects under DC electric field. The optical transmittances of the planar and homeotropically aligned liquid crystal cells, which were prepared by conventional rubbing and photolithographic technique on the polyimide thin films for molecular alignment, were measured in their phase transition region. The results of measurement for both orientations, the distribution curve of the optical transmittance exhibits displacement toward to low level at the beginning and then to high level by the temperature variations, while the electric field increases. It was also observed that the domain structure of the materials were affected considerably by the applied electric field and phase transition region of the aligned structures had broader range than by the pure crystalline structure and its phase transition temperature was changed by the molecular anisotropy. Finally, in photolithographic method strong bonds between the molecules and the orienting surface were observed in high contrast to rubbing method.

Synthesis of New Binder Polymers for Photolithographic Patterning of Black Pixel Define Layers of Organic Light Emitting Diode

The fabrication of black pixel define layer (PDL) on the organic light emitting diode (OLED) panel has been developed actively by using negative-tone black photoresist which contain photoinitiator, photosensitizer, binder polymer, multifunctional monomer and black mill base in order to improve the outdoor visibility of OLEDs. Cardo type binder polymer containing bulky and rigid fluorene group has been widely used in the black photoresist formulation. However, the commercial cardo binder polymer has high cost and requires high UV dose for the fine patterning of PDL in the photolithographic process. In this study we designed and synthesized various non-cardo type binder polymers and evaluated the new binder polymers in comparison with the cardo binder polymer for the improved patterning of PDL on the OLED panel.

Mechanical system and dynamic control in photolithography for nanoscale fabrication: A critical review

As one of the most advanced and precise equipment in the world,a photo-lithography scanner is able to fabricate nanometer‐scale devices on a chip.To realize such a small dimension,the optical system is the fundamental,but the me-chanical system often becomes the bottleneck.In the photolithography,the ex-posure is a dynamic process.The accuracy and precision of the movement are determined by the mechanical system,which is even more difficult to control compared with the optical system.In the mechanical system,there are four crucial components:the reticle and wafer stages,the linear motor,the metrology system,and the control system.They work together to secure the reticle and substrate locating at the correct position,which determines the overlay and alignment per-formance in the lithography.In this paper,the principles of these components are reviewed,and the development history of the mechanical system is introduced.

Advancing microarray fabrication:One-pot synthesis and highresolution patterning of UV-crosslinkable perovskite quantum dots

The development of highly efficient,solution-processable,and environmentally stable perovskite quantum dots(PQDs)is crucial for their accurate high-resolution patterning and subsequently enabling the practical deployment of PQD based emissive display devices.This study presents an innovative strategy for integrating all-inorganic PQDs and ultraviolet(UV)crosslinkable acrylate polymer at a structural and functional level.The achievement is accomplished by meticulous design and one-pot synthesis of UV-crosslinkable CsPbX3(X=Cl,Br,I)PQDs solution,which exhibit outstanding environmental stability.Leveraging the solution-processable characteristics of the resulting UV-crosslinkable PQDs,precise patterning of high-resolution(2μm,7608 pixels·in.-1)and colorful PQDs microarrays can be readily achieved through inkjet printing and high-throughput photolithography(~2μm in pitch line/space patterning).The UV cross-linked process guarantees a homogeneous distribution of PQDs,effectively mitigating coffee ring effect and improving the overall quality of stereoscopic microarrays.The photo-cured PQDs film,which undergoes free radical photopolymerization,displays an impressive photoluminescence quantum yield(PL QY)of up to 89.2%,reaching 98%of the value observed in the solution state.The approach outlined in this research is both cost-effective and pragmatic,exhibiting tremendous promise for diverse system-level integrated optoelectronic devices,such as ultra-high-resolution micro-light-emitting device(micro-LED)displays.

High-resolution, full-color quantum dot light-emitting diode display fabricated via photolithography approach

Displays play an extremely important role in modern information society,which creates a never-ending demand for the new and better products and technologies.The latest requirements for novel display technologies focus on high resolution and high color gamut.Among emerging technologies that include organic light-emitting diode(OL ED),micro light-emiting diode(micro-LED),quantum dot light-emitting diode(QLED),laser display,holographic display and others,QLED is promising owing to its intrinsic high color gamut and the possibility to achieve high resolution with photolithography approach.However,previously demonstrated photolthography techniques suffer from reduced device performance and color Impurities in subpixels from the process.In this study,we demonstrated a sacrificial layer assisted patterming(SLAP)approach,which can be applied in conjunction with photolithography to fabricate high-resolution,full-colo quantum dot(QD)patterns.In this approach,the negative photoresist(PR)and sacrificial layer(SL)were uilized to determine the pixels for QD deposition,while at the same time the SL helps protect the QD layer and keep it intact(named PR-SL approach).To prove this method's viability for QLED display manufacture,a 500-ppi,full-color passive matrix(PM)-QLED prototype was fabricated via this process.Results show that there were no color impurities in the subpixels,and the PM-QL ED has a high color gamut of 114%National Television Standards Committee(NTSC).To the best of our knowledge,this is the first ull-olor QLED prototype with such a high resolution.We anticipate that this innovative patteming technique will open a new horizon for future display technologies and may lead to a disruptive and innovative change in display industry.

Microstructuring of carbon/tin quantum dots via a novel photolithography and pyrolysis-reduction process

A novel microfabrication process based on optimized photolithography combined with pyrolysis-reduction is proposed to fabricate interdigital porous carbon/tin quantum dots （C/Sn QDs） microelectrodes.C/Sn QDs active microelectrodes are also employed as current collectors of a micro-supercapacitor （MSC）.A uniform dispersion of Sn QDs （diameter of ～3 nm） in the carbon matrix is achieved using our facile and controllable microfabrication process.The as-fabricated C/Sn QDs MSC obtained by carbonization at 900 ℃ exhibits a higher areal specific capacitance （5.79 mF＆#183;cm-2） than that of the pyrolyzed carbonbased MSC （1.67 mF＆#183;cm-2） and desirable cycling stability （93.3% capacitance retention after 5,000 cyclic voltammetry cycles）.This novel microfabrication process is fully compatible with micromachining technologies,showing great potential for large-scale fine micropatterning of carbon-based composites for applications in micro/nano devices.

Enhanced light extraction of InGaN LEDs with photonic crystals grown on p-GaN using selective-area epitaxy and nanospherical-lens photolithography

We report a new method for the fabrication of two-dimensional photonic crystal （PhC） hole arrays to improve the light extraction of GaN-based light-emitting diodes （LEDs）. The PhC structures were realized using nanospherical-lens photolithography and the selective-area epitaxy method, which ensured the electrical properties of the LEDs through leaving the p-GaN damage-free. At a current of 350 mA, the light output power of LEDs with PhC hole arrays of 450 nm and 600 nm in diameter with the same lattice period of 900 nm were enhanced by 49.3% and 72.2%, respectively, compared to LEDs without a PhC. Furthermore, the LEDs with PhC hole structures showed an obviously smaller divergent angle compared with conventional LEDs, which is consistent with the results of finite-difference time-domain simulation.

Optical system and lens design for Blu-ray disc optical pick-up

During the design process of Blu-ray disc optical pick-up （BD OPU）, the optical system and the collimator lens design is especially important. This paper designs an optical system and some lenses for＇the BD OPU, including collimator lens, beam shaping lens for laser beam shaping, and cylinder lens for signal detecting. In this OPU, we use a triplet lens to collimate the laser beam. At the same time, we build a series of assembly jigs to make sure that each lens can be put into the OPU basement properly. At last, we get the reading spot image and S-curve photo of OPU, which can be used to read Blu-ray disc （BD）.

PMMA-Based Microsphere Mask for Sub-wavelength Photolithography

The authors present a polymethyl methacrylate(PMMA)-based,reusable microsphere mask used in the laser sub-wavelength photolithography.In order to overcome the diffraction limit to achieve nano-structuring using l-|im laser wavelength,the photolithography technique was conventionally characterized by applying a one-off monolayer of silica microspheres serving as Mie scatterers.Addressing the major limitation of this technique,which was that the monolayer of microspheres must be prepared on the sample surface prior to fabrication,the proposed hot press approach could firmly fuse the 1silica microspheres to the PMMA base without the use of adhesives.The PMMA-based microsphere mask could hence reduce the amount of work for the monolayer preparation and was proven reusable for at least 20 times without damage to top or bottom surfaces.Using the mask,dimples that were 0.7 pm in diameter and 40 nm in depth were produced on tool steel by a single pulse of picosecond laser irradiation.