Nano Patterns Research Articles

A Fabrication Method of the Silica-Based Moth-Eye Structures and Its Application to the Organic Light-Emitting Diodes

For the application of moth-eye patterns to practical optical devices, a novel nano-patterning technique, which can fabricate transparent and robust material based nano patterns through a simple process, needs to be developed, because the moth-eye structures are usually exposed to the outer environment. In this study, silica based moth-eye structures were directly fabricated on a glass substrate by the direct hydrogen silsesquioxane (HSQ) printing and annealing technique. The transmittance of the glass substrate was enhanced by 3–4% in the visible range by the silica moth-eye structures and it was confirmed that the light output efficiency of the green organic-light emitting diode (OLED) was enhanced by 7–9% using the encapsulation glass with the silica moth-eye patterns.

Nano-patterning of a TiO 2-organic hybrid material using interference of surface plasmon on aluminum

Nano patterns of a TiO 2-organic hybrid material have been fabricated by interference of surface plasmon on aluminum. The TiO 2-organic hybrid materials were prepared by the sol–gel method, and were irradiated through an aluminum mask by a UV light. After the unreacted parts were removed, patterns were obtained on the films. The patterns of lines approximately 300 nm in width and with a sub-100-nm height were obtained by controlling the UV irradiation time. It was confirmed that the patterns changed to anatase patterns by sintering at temperatures above 450 °C.

Hard x-ray nano patterning using a sectioned multilayer

We report a hard x-ray patterning capable of drawing lines with a width below100 nm using x-rays at 0.165 nm. A specially prepared mask based on multilayer growth technology was used as an x-ray mask effectively. The x-ray Talbot effect in near field was investigated and utilized in the patterning. Since multilayers with a few nanometer layer spacing are readily available, the proposed hard x-ray nano patterning, free of the limit imposed by the Rayleigh criterion in optical range, can potentially be an ultimate optical lithography technique.

Fabrication of the metal nano pattern on plastic substrate using roll nanoimprint

The demand for fine metal-patterning techniques has increased to include fabrication of a range of next-generation devices, such as nano-scale electrodes, as well as plasmon photonic and optical devices. In addition, a plastic substrate is strongly desired for these devices because of its transparency, flexibility, lightness and low cost. Moreover, a technique offering higher throughput is required for the fabrication of large devices at low cost. In order to achieve simultaneously high resolution and high throughput, we have developed a three-dimensional metal-pattern nanoimprint technique that uses a metal oxide release layer. In this study, a metal pattern nanoimprint technique using a roll mold that produces a seamless nano-pattern with an ultraviolet curable resin was examined to obtain rapidly a nano-scale metal pattern on a plastic substrate. The seamless roll mold was fabricated by a direct writing method using an electron beam. As a result, a seamless metal nano pattern on a plastic substrate was obtained by roll-to-roll metal nanoimprinting with a metal oxide release layer.

Anodic Aluminum Oxide 기반 니켈 스탬퍼를 이용한 나노패턴 성형에 관한 연구

For the fabrication of nano patterned products manufacturing a nano patterned mold is needed in advance. The nano patterned stamper was fabricated by electroforming the AAO master with nickel. The surface of nickel-plated stamper had nano-patterned holes with the diameter of 73 nm and the depth of 83 nm. Hot embossing was used for forming P3HT sheet and the process factors of hot embossing were closer as pressure, temperature and time. In the present paper hot embossing experiments were performed to find the main process conditions to affect the replication ratio of nano patterns on surface of P3HT sheet. As a result, main contributing factors for the replication ratio of hot embossed pattern could be sequentially enumerated as pressure, temperature and time.

Homeotropic alignment of liquid crystals on a nano-patterned polyimide surface using nanoimprint lithography

In this paper, nanoimprint lithography was utilized to transfer a nano-pattern (NP) onto a homeotropic polyimide (PI) surface for use in liquid crystal displays (LCDs). The nano-patterned silicon mold was fabricated by laser interference lithography. A NP PI layer acted as the homeotropic alignment layer to easily and uniformly align the liquid crystal (LC) molecules. A NP LC cell with a NP PI layer was successfully operated as a vertical aligned LCD, and its performance was evaluated. The threshold voltage and response time of the NP LC cell were 2.472 V and 22.7 ms, respectively. In addition, the NP LC cell was characterized by a high thermal budget. Therefore, the competitive performance of the NP LC cell could allow new approaches to replace the conventional rubbing process in display technology.

Transparent Roll Mold Fabrication Method and Transfer to Photo-curable Polymer

In the next-generation, a high throughput fine patterning process with low cost is required to fabricate various devices, which have a nanometer-scale pattern over a large area. Ultra violet nanoimprint lithography (UV-NIL) is a major breakthrough in this field because it is considerably simpler than the conventional techniques and the equipment cost of a NIL system is inexpensive. Furthermore, NIL with roll mold (Roll nanoimprint, RNIL) has received a lot of attention because of its very high throughput and high resolution. Generally, a roll mold with nano pattern is obtained by the attachment of a planar replica mold. However, the resulting roll mold has seams and this brings about a yield loss of the product. Therefore, we have developed a direct writing method using EB lithography on a rotating cylindrical substrate. In this study, we examined a fabrication method of seamless roll mold using transparent roll substrate and RNIL was carried out using a UV photo-curable resin.

Nano Patterning on Surfaces of 3-D Micro Structures by Means of Block Copolymer Self Assembly

ABSTRACTIn this paper, we present the possibility of nano-scale patterning on surfaces of 3-D micro structures by means of block copolymer self assembly. We succeeded in forming vertical cylinders on the surfaces of the 3-D micro structures using dip-coat process with Au deposition instead of random copolymers. The material of 3-D structures fabricated by FIB-CVD was diamond-like carbon (DLC) due to selecting phenanthrene as a gas source. Since the surface energy of DLC is low, instead of PS-r-PMMA polymer brush, 100 nm-thick Au films were coated on the surfaces of 3-D structures. PS-b-PMMA (PS:PMMA = 50 kg/mol:21 kg/mol) was dip-coated on the Au coated surfaces and annealed. First, we prepared DLC 60° angled slope with size of 2.5 by 3 μm2. As a result, the vertical cylinders were formed in a similar way regardless of the places, i.e., top, middle and bottom on the slopes. vertical cylinders were formed regularly and densely on the entire slope. In order to investigate the effect of slope angle, we prepared 3-D micro structures with different angled slopes such as 70, 80 and 90°. There was no slope angle specific difference, and vertical cylinders were also formed on each slope.

1J1348 電子線励起作用による細胞膜上のナノパターン生成と生体分子操作にむけた応用(計測,第49回日本生物物理学会年会)

1J1348 電子線励起作用による細胞膜上のナノパターン生成と生体分子操作にむけた応用(計測,第49回日本生物物理学会年会)

The configurable-biomolecular nano pattern controlled by surface potential

Biomolecular patterning on surfaces plays a critical role in the field of biochip developments. Therefore, we designed and fabricated a device to realize the programmable biomolecular patterning technique driven by electrical surface potentials. In this work, the electrical surface potential was used to control the hydrophobicity of surfaces. Utilizing hydrophobicity interactions, the adhesion affinity between biomolecules and chip surfaces can be modulated by the applied electrical field. By activating the electrical potential of specific electrodes, biomolecules can attach to specific regions as designed or programmed. Based on this technique, in addition, we demonstrated the 250nm width bovine serum albumin (BSA) pattern with a 5-min operation. This work shows the potential for various biomolecular applications and research fields.

Fabrication of a Nanosize Pattern Embedded Plastic Chip via an Injection Molding Method for Application to an Optical Biosensor

Abstract We demonstrate a commercialized injection molding method for nano patterning of polymethyl methacrylate (PMMA) for the purpose of mass production of a label-free optical biosensor chip. Scanning electron microscope (SEM) images clearly show uniform nanopattern transfer on the plastic chip fabricated by an injection molding method. A uniformly deposited silicon nitride layer having a high refractive index by a plasma enhanced chemical vapor deposition (PECVD) technique is also observed. A unique characterization method is described wherein optical resonance reflection is used accurately and quickly to characterize the geometrical sensor structure. The authors anticipate that this robust method will provide an excellent means of producing an optical resonance reflection biosensor (ORRB).

Size Tunable Nano Patterns Using Nanosphere Lithography with Ashing and Annealing Effect

This work presents a fabrication procedure to make large-area, size-tunable, periodically different shape metal arrays using nanosphere lithography (NSL) combined with ashing and annealing. A polystyrene (PS, 580 mu m) monolayer, which was used as a mask, was obtained with a mixed solution of PS in methanol by multi-step spin coating. The mask morphology was changed by oxygen RIE (Reactive Ion Etching) ashing and temperature processing by microwave heating. The Au or Pt deposition resulted in size tunable nano patterns with different morphologies such as hole and dots. These processes allow outstanding control of the size and morphology of the particles. Various sizes of hole patterns were obtained by reducing the size of the PS sphere through the ashing process, and by increasing the size of the PS sphere through annealing treatment, which resulted in tcontrolling the size of the metallic nanoparticles from 30 nm to 230 nm.

Formation of TiO2 Nano Pattern on GaN-Based Light-Emitting Diodes for Light Extraction Efficiency

A TiO2 nano-structure was formed on the indium-tin-oxide electrode of a GaN-based light-emitting diode (LED) in order to enhance the light extraction efficiency. The UV bi-layer imprinting and lift-off processes were used to form the TiO2 nano-structure without any plasma etching process, which can lead to degradation of the electrical properties of the device. As a result, the light output power of the LED on the patterned sapphire substrate (PSS) with the TiO2 nano-structure was enhanced up to 12% compared to identical LED formed on the PSS without TiO2 nano-structure. No electrical degradation was observed for the patterned LED device.

Possibility of Pulsed Electrochemical Processes to Nanofabrication Using Scanning Probe Oxidation

This study demonstrates nano-scale lithography process on localized (100) silicon (p-type) surface using modified AFM apparatuses and controlling methods. AFM-based experimental apparatuses are connected the customized pulse generator that supplies electricity between conductive tip and silicon surface maintaining constant humidity during processes. Then pulse durations are controlled according to various experimental conditions. The pulsed electrochemical reaction within the gap between conductive tip and silicon surface induces the formation of oxide with nano-scale topographies. Various heights and widths of oxides can be created by AFM surface modification according to various pulse durations and applied electrical conditions under humidity environment. In addition, it can be known that oxides are completely removed after sample surface is etched in diluted HF solution, which shows micro/nano-scale grooves can be fabricated after predefined chemical treatment. They are wider than oxides widths and have several nanometer depths. Nano patterning technique from this experiment suggests that pulse electrochemical machining process has bright potential for advancing nano machining technologies.

Continuous roll-to-flat thermal imprinting process for large-area micro-pattern replication on polymer substrate

Conventional imprinting process in flat-pressing mode meets with the problem of limited efficiency as a discontinuous batch-wise process in many new applications that demand micro-/nano pattern replication over large area with low cost and high throughout in mass production manufacturing. To overcome such problem, alternative imprinting process in a continuous roller-pressing mode has been gaining more attention since it has many advantages. However, few studies have been reported on the investigation of filling mechanism in roller-pressing type imprinting process. In order to have a better understanding of polymer flow behavior in roller-pressing type imprinting process, it is necessary to establish a criterion of evaluation for roller-pressing type imprinting process. In this paper, an analytical model for the cavity-filling of polymer flow in roll-to-flat (R2F) imprinting process is derived based on Hertz contact pressure distribution and Navier–Stokes equation. The feasibility of the model is evaluated using a lab-scaled prototype of a R2F micro thermal imprint system for micro-pattern replication over large area on polymer substrate. Series of tests are conducted to investigate the effects of process control parameters on the replication ratio. In results, there is good agreement between the model prediction and experiments when pattern replication is examined according to the change of control parameters such as rolling speed and loading pressure.

Low Oxygen Tension and Synthetic Nanogratings Improve the Uniformity and Stemness of Human Mesenchymal Stem Cell Layer

A free-standing, robust cell sheet comprising aligned human mesenchymal stem cells (hMSCs) offers many interesting opportunities for tissue reconstruction. As a first step toward this goal, a confluent, uniform hMSC layer with a high degree of alignment and stemness maintenance needs to be created. Hypothesizing that topographical cue and a physiologically relevant low-oxygen condition could promote the formation of such an hMSC layer, we studied the culture of hMSCs on synthetic nanogratings (350 nm width and 700 nm pitch) and either under 2 or 20% O(2). Culturing hMSCs on the nanogratings highly aligned the cells, but it tended to create patchy layers and accentuate the hMSC differentiation. The 2% O(2) improved the alignment and uniformity of hMSCs, and reduced their differentiation. Over a 14-day culture period, hMSCs in 2% O(2) showed uniform connexon distribution, secreted abundant extracellular matrix (ECM) proteins, and displayed a high progenicity. After 21-day culture on nanogratings, hMSCs exposed to 2% O(2) maintained a higher viability and differentiation capacity. This study established that a 2% O(2) culture condition could restrict the differentiation of hMSCs cultured on nanopatterns, thereby setting the foundation to fabricate a uniformly aligned hMSC sheet for different regenerative medicine applications.

Design and validation of a novel master-making process chain for organic and large area electronics on flexible substrates

This paper presents a novel process chain for fabrication of replication masters for serial manufacture. The proposed process chain is validated for serial fabrication of (large area) organic electronic devices on flexible substrates. The advantages and limitations of the component technologies in the proposed manufacturing route are discussed and their interdependencies in a process chain for producing both 2.5D and 3D nano- and micro-structures are analysed. The proposed master-making route relies on using different technologies for micro-structuring and sub-micron and nano patterning that are applied to the fabrication of Ni shims incorporating different length scale features. In particular, the capabilities of photolithography as a micro-structuring technology were combined with those of FIB machining to add sub-micron and nano-features on micro patterned fused silica templates. Then, by applying UV nanoimprint lithography such templates were validated and their nano and micro-structures were consistently replicated in one step. Finally, the feature transfer of such imprints onto Ni shims was also successfully accomplished with only minor deviations from the target dimensions.

Fabrication and characterization of CdTe nano pattern on flexible substrates by nano imprinting and electrodeposition

Nano imprinting technology and the electrodeposition method were applied to make CdTe nano patterns on flexible substrates. An ammonia based aqueous solution was prepared at pH 10.7 and indium tin oxide (ITO)/polyethylene naphthalate (PEN) film with template was used as the working electrode. ITO thin film which was coated on PEN film had good electrical conductivity and optical transmittance. The template was manufactured by nano imprinting technology on ITO/PEN film. It was made from benzyl methacrylate and had nano rod arrays. It was used as the working electrode and for making CdTe nano pattern. CdTe nano pattern were analyzed by X-ray diffractometer, dual beam (DB)-focused ion beam (FIB)-scanning electron microscopy (SEM), Raman spectroscopy, and ultraviolet (UV)–visible (VIS) spectroscopy. The structure and optical properties of CdTe nano pattern on flexible substrates was analyzed. The crystalline size of nano pattern had 8.26 nm. The Te particles that were precipitated on CdTe surface seems to be exist. The absence of annealing process influenced to have low absorption coefficient and narrow band gap compared to bulk CdTe. However, nano pattern increased reflectance.

Fabrication of micropatterns of nanoarrays on a polymeric gel surface

Micro-nano patterns of gold on the surface of poly(ethylene glycol) (PEG) hydrogels were prepared. The approach combines the technique of conventional photolithography (a top-down method for micropatterns), block copolymer micelle nanolithography (a bottom-up method for gold nanopatterns), and a linker-assistant technique to transfer a pattern on a hard surface to a polymeric surface. Hybrid micro-nano patterns on hydrogels were characterized using scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. The patterned Au nanoparticles were further modified by a peptide containing arginine-glycine-aspatate (RGD). The cell-adhesion contrast of the patterned hydrogel surface was confirmed by preliminary cell experiments.

Three-dimensional Metal Nano Pattern Transfer on PET using Metal Oxide Layer

There is a strong need for a fine three-dimensional metal patterning technique for fabricating next-generation devices such as patterned media and plasmon photonic and nano-scale electrodes. In addition, flexible and transparent electronic devices on plastic substrates are desired for wearable devices and flexible thin-film displays. Therefore, a technique for patterning metals onto plastic substrates is required. Nanotransfer printing (nTP) has received much attention recently because of its high throughput and high resolution compared to inkjet printing. However, it is difficult to create sub-100 nm metal patterns using nTP because the PDMS stamp is deformed by transfer pressure. Therefore, we have developed a technique for transferring three-dimensional metal patterns onto a polyethylene terephthalate (PET) substrate by nanoimprint lithography using a metal oxide release layer. The three-dimensional nanoimprint mold was fabricated by control of acceleration voltage electron beam lithography (CAV-EBL) with spin-on-glass (SOG). As a result, three-dimensional metal nano patterns were obtained using a metal oxide release layer. Moreover, the metal moth-eye structure, which has a very high aspect ratio, was transferred onto a PET substrate by applying our process to the moth-eye structure on glassy carbon.