The Photopolymer Science and Technology Award No. 191100, the Outstanding Achievement Award 2019 was presented to Dr. Robert D. Allen (IBM Research, Almaden) for his outstanding achievements in photopolymer science and technology, “Pioneering semiconductor patterning technology using water immersion ArF lithography with the originally designed photoresist”.

The Photopolymer Science and Technology Award No. 192100, the Best Paper Award 2019, was presented to Hiroaki Takehara, Yukihiro Kanda, and Takanori Ichiki (Department of Materials Engineering, School of Engineering, The University of Tokyo) for their outstanding contribution published in Journal of Photopolymer Science and Technology, 31, (2018) 59–63, entitled “Microfluidic Model for Optical Detection of Nanoparticles in Whole Blood”.

The Photopolymer Science and Technology Award No. 192200, the Best Paper Award 2019, was presented to Satoshi Takei, Makoto Hanabata, Kento Mizui, Kazuho Kurematsu, and Shinya Nakajima (Departments of Mechanical Systems Engineering and Pharmaceutical Engineering, Toyama Prefectural University) for their outstanding contribution published in Journal of Photopolymer Science and Technology, 31, (2018) 289–294, entitled “Reduction of Defect for Imprinted UV Curable Resin including Volatile Solvents using Gas Permeable Mold Derived from Cellulose”.

We investigated the optical characteristics of a single-mode polymer waveguide in the visible wavelength region, including the blue range. We fabricated two types of polymer waveguide by using photolithography and UV-nanoimprint lithography. The polymer waveguides had an over and under cladding, and the refractive index difference between core and cladding was 0.8% at a wavelength of 633 nm. The propagation loss of the fabricated waveguide was about 0.8 to 4.4 dB/cm at wavelengths from 638 to 465 nm. The waveguide worked as a single-mode one over the whole visible region.

Extreme Ultraviolet (EUV) lithography utilizes photons of 91.6 eV energy to ionize resists, generating secondary electrons, thus enabling electron-driven reactions. Unlike photolithography, where photons below 7 eV selectively activate photoactive compounds, photons at 91.6 eV ionize all materials, subsequently generating secondary electrons. The energy and the numbers of secondary electrons generated after ionization are determined by the material chemistry. Several metals are reported to have high secondary electron generation capability and high EUV absorption, therefore metals can be one of the solution to deal with the insufficient photon density in resist. Halogen atoms like iodine and fluorine also provide high absorption which would be suitable alternative sensitizer to the metal salts sensitizer. In this work, we study metal salt sensitizers with different cations and anions as well as halogenated sensitizer in both polymer and PAG. Total electron yields are increased with increased resist absorption for both metal and halogen sensitizer. Sensitivity of resists with metal salt sensitizers increase, resulting in increased LCDU. However, halogenated sensitizers do not show positive correlation between sensitivity and electron yield as metal sensitizer. Through this study, we expect to explore materials that enable both high absorption and high photoelectron generation efficiency at 91.6 eV.

In this paper, we fabricate Epoxy/ZnO-GO composite films using photoinduced cationic ring opening polymerization processes with self-cleaning ability and improved thermal properties under the photo exposure. The presence of ZnO nanoparticles on the GO surface aids in achieving good self-cleaning properties by removing model dirt, methylene blue, (within 1-2 h) under sunlight. An increase of almost 15 ℃ in the thermal stability was obtained by introduction of 0.6 wt% ZnO-GO to the epoxy matrix. Therefore, the nanocomposite could be a promising futuristic material for many advanced applications and used as a surface coating material where it can remove the presence of organic dirt and provide a clean surface.

The effects of polymer gel electrolyte on the photoelectric and driving characteristics of Prussian blue (PB)-based electrochromic (EC) cells were systematically investigated under different preparation conditions. The EC cells were switched from the coloring to decoloring mode by applying ±1.5 V. Subsequently, we prepared an automatic driving circuit wherein the signal of the voltage was alternately applied. The thickness of the PB layer significantly depended on the switching speed as opposed to the electrolyte concentration and the polymer gel electrolyte. In particular, the speed of coloring exceeds that of decoloring due to the electron exchange in the chemical reaction. The speed varied from approximately 5 to 10 times based on the type of the electrolyte.

To ensure easier removal of adhesive, backing materials can be coated with a release film. UV-curable release coatings based on acrylate or epoxy silicone oligomers represent an increasing proportion of release liners available on the market. In order to alleviate their current problems of recycling, metal contamination and initiator insolubility, we have developed a synthetic methodology able to reduce silicone content below 1 wt%. Silicon monomer-free, our approach relies on a type II radical photoinitiator consisting of benzophenone and poly(methylhydrosiloxane) (PMHS, 1600 g/mol), a silicone derivative with the general structure O-Si(H)(CH₃). The ability for PMHS to act as co-initiator in radical photopolymerization is revealed by real-time Fourier transform IR spectroscopy. Release properties are evaluated through a probe tack experiment using a commercial pressure sensitive adhesive. Using 1,6-hexanediol diacrylate as resin, release properties are achieved at 1 wt% PMHS, and can be also maintained with poly(ethylene glycol) diacrylate, or tripropylene glycol diacrylate monomers. A ten times decrease in adhesion energy is observed when PMHS is used against a non-reactive silicone thanks to chemical bonding between co-initiator and polymer network.

Polypyrrole (PPy) is synthesized via in situ chemical oxidative polymerization in the presence of acid fuchsin (AF) which works as both the dopant and structure-guiding agent for polymerization of pyrrole. The electronic conductivity is measured in detail, showing that the addition of AF plays a key role in regulating and even deciding the morphology and the electronic conductivity of the resulting PPy. In addition, the effects of some polymerization conditions including temperature, reaction time, kinds of doping acid and oxidant on the electronic conductivity are investigated. And the reason for the changes of performance are also explained.

A methodology to measure photoresist absorption under soft X-ray radiation is presented in this work. The high photoresist sensitivity required for the extreme-ultraviolet lithography (EUVL) technology can be achieved by increasing the EUV photon absorption of photoresist material, hence high extinction coefficient is preferred. To determine the extinction coefficient of a photoresist, a small-scale manufacturing process has been developed to obtain free standing thin silicon nitride (SiN) membranes and use it as sample holder for photoresist thin film characterization. The SiN membrane has been characterized in terms of film thickness, composition and density. Transmission measurements through the thin films of SiN and photoresist have been carried out in the energy range between 90.6 eV and 92.6 eV by using X-ray Absorption Spectroscopy (XAS) at the BEAR beamline Elettra synchrotron research facility, in Italy. The method permits an experimental measurement of the absorption coefficient of thin films, with an accuracy of 3 ×10⁻⁴, providing a tool helpful for EUV photoresist research and development.

Utilizing semi-cylindrical patterns of negative resist SU-8, lenticular lens arrays with a fine lens pitch of 100 µm were fabricated. The patterns were formed on 240-µm thick quartz plates coated with 100-µm thick SU-8 by the defocused projection exposure using a normal reticle with 50-µm line-and-space (L&S) patterns. Because the SU-8 was almost transparent for visible light with wavelengths longer than 400 nm, the patterns were directly used as lenticular lens arrays as they were. Next, a lenticular lens array set was assembled by placing a quartz plate with the lens patterns on an apple picture covered with a film reticle of 50-µm L&S patterns. When the set was observed with great interest, two scenes of an apple and all black were successfully switched alternately. Because the lens pitch of 100 µm was considerably smaller than the conventional one of 254 µm, smoothness of the picture edge was notably improved especially at inclined parts of the pictures. However, the angle for switching the two scenes was as small as approximately 6º. It was discussed that the small angle switching was caused by the substantial thickness of the lens array set including thicknesses of the quartz plate and the reticle film, and the angle might be controllable by decreasing the thickness.

The effective initiation for the chain-growth Horner-Wadsworth-Emmons (HWE) condensation polymerization was succeeded by utilizing an aliphatic aldehyde. Due to the higher electrophilicity of the aliphatic aldehyde compared with the aromatic one, the reactivity of the initiation might be accelerated, producing uniform intermediates to result in the formation of well-defined poly(3-(2-ethylhexyl)thienylene vinylene) (P3EHTV). Consequently, P3EHTV possessed the predictable molecular weight and lower molar-mass dispersity (Ð_M =1.16) value than that of P3EHTV obtained by employing aromatic aldehyde compounds as the initiators. In this polymerization system, neither transition metals nor halogens are utilized to realize low environmental-load synthesis of well-defined π-conjugated polymers.

We have developed Pilot #1 system for HVM EUV lithography. Pilot#1 is up running and it demonstrates HVM capability. We achieved following performances at present; High conversion efficiency 4.5% is realized with Pre-pulse technology. High speed (>90 m/s) & small (20 micron) droplet is realized. High power CO₂ laser power level is 20 kW. Output power 250 W in-burst power @50% duty (125 W average) several min. Pilot#1 system achieved potential of 89% availability (2 weeks) at 125 W average power. −0.6%/Gpls with 125 W average was demonstrated during 30 Mpls with mirror test.

 Furthermore, in 2018 ASML reported they succeeded 250 W operation with NXE3350 system achieved 125 WPH throughput not only in laboratory but also several customer site. Corresponding this situation, we have redefined the new target of EUV source power more than 330 W recently. We have already started feasibility study of higher conversion efficiency, higher driver laser power and improvement of capping layer of collector mirror. We will report the preliminary result of these.

With the scaling evolution of logic and memory technologies the extreme ultraviolet lithography (EUVL) technology is becoming part of the high-volume manufacturing device landscape. Currently, the single patterning of both logic metal layer and DRAM storage layer are approaching the resolution limit on the 0.33NA full field exposure scanner. Furthermore, because the logic technology nodes are scaling at a faster pace than memory nodes, the development of leading-edge logic node (N5) will move first the EUVL insertion from a single patterning to a double patterning technology with relaxed pitches to overcome the current 0.33NA EUVL limits. In this paper, the EUV photoresist challenges are discussed on the horizon of up-coming industry technology nodes.

In this study, tissue-penetrable near infrared (NIR)-II fluorescent polystyrene latex nanoparticles (NIR-PSt NPs) were designed and prepared as deep tissue in vivo imaging probes. An NIR-II fluorescent dye was successfully loaded into PSt NPs. The resulting NIR-PSt NPs showed strong NIR-II (1100 nm) emission in an aqueous environment. In addition, in vivo imaging of live mice was successfully performed using these NIR-PSt NPs. The prepared NIR-PSt NPs exhibited remarkable properties for in vivo fluorescence imaging.

In recent years, isothermal nucleic acid amplification techniques have been developed as alternatives to polymerase chain reaction (PCR) requiring thermal cycles. The integration of isothermal amplification into electrical or electrochemical devices realizes high throughput nucleic acid-based assays and confers high sensitivity. In this research, we tried to develop electrical/electrochemical biosensors detecting nucleic acids aiming at application to future liquid biopsy. For detection of small DNAs or microRNAs (miRNAs), isothermal amplification methods were employed, and the signal changes based on the extension reaction by polymerases were detected using electrical/electrochemical devices, namely, a chronocoulometric sensor and a micro pH sensor. These small sensors based on electrochemical technique might be a promising tool in on-site detection of nucleic acids related to cancer diagnosis.

This paper described the design and fabrication of precursor for Au hole structure with four edges (edged hole array: EHA) for sensor application. In this paper, effect of the gap length of opposite edges g and hole side length l was investigated systematically by simulation. As the result, optimal design of EHA that shows strong light absorption (> 90%) and electric field (1.79×10⁵-fold increase against the incident light) at λ = 785 nm was revealed. Finally, the precursor resist pattern for EHA was fabricated using electron beam lithography and cold development. As the result, the precursor structure that was expected to generate strong electric field at λ = 785 nm was successfully fabricated.

The poly(dimethylsiloxane) (PDMS)-based microchannel of a microcapillary chip is attractive for characterization of nanoparticles (NPs). The surface potential of PDMS is negative in nature, and in the presence of charged NPs, an interaction exists between the NPs and microchannel surface. In this study, the adsorption phenomena of nanoliposomes in the microchannel was investigated using a microfluidic chip designed for the autonomous compensation of hydrostatic pressure flow in the presence of neutral or cationic polymer coating. The Brownian motion of the nanoliposomes in the region of interest was stably observed without any fluid flow. The adsorption phenomena of the nanoliposomes on the microchannel surface arose from hydrophobic and electrostatic interaction, and can be attenuated based on electrostatic repulsion and the excluded volume effect.

Indocyanine Green (ICG) is one of the most common fluorescent dyes that emits in the near-infrared (NIR) region, with extensive use in the medical field. However, this dye is susceptible to photobleaching, thermal degradation and oxidation in acidic conditions. The major pathway by which ICG photobleaches involves sensitization to form singlet oxygen, which can react with the dye’s backbone, resulting in decomposition to non-fluorescent debris. In this paper we introduce the concept of using energy transfer (ET) for the protection of NIR dyes against photodecomposition. The dye IR-1061 was chosen as an ET pair due to its spectral overlap with ICG. First, it was shown that the presence of the former in solution reduced disintegration of the latter by absorbance and fluorescence spectroscopy. A singlet oxygen-reactive fluorescent indicator was employed to demonstrate that the production of this reactive species is also greatly reduced. This photoprotective effect was improved by encapsulation of the dyes in phospholipid-PEG micelles, which reduces the distance between them, thus enhancing the ET efficiency. The micelles were characterized for their optical properties and their size was determined to be about 10 nm with dynamic light scattering (DLS) techniques. The ET particles displayed greater fluorescence over 1000 nm compared to either dye encapsulated alone. The micelles proved to be superior than the free dye in terms of chemical, thermal and photo-stability. Moreover, the system demonstrated improved heating due to a greater photothermal effect compared to ICG dye in free or encapsulated form.

Bubble-free filling is required to realize high-throughput mass production in ultraviolet nanoimprint lithography (UV-NIL). UV-NIL in 1-chloro-3,3,3-trifluoropropene (CTFP) and trans-1,3,3,3-tetrafluoro-propene (TFP) gases has enabled bubble-free UV nanoimprinting of spin-coated films without a vacuum. We evaluate the amount of gas dissolution of 24 organic solvents, which was measured using an electronic balance in a glove box with saturated gases of CTFP and TFP, and use the Hansen solubility parameters (HSP) for analysis. Although the HSP teas graph indicated the same solubility trend in TFP and CTFP atmospheres, the amount of TFP gas dissolution was 1/5th that of CTFP. The pattern quality of acrylate UV-curable resins, which absorb well the condensable gases, was also demonstrated by altering the fraction of the introduced condensable gas mixture of TFP/CTFP. Fine line patterns with a width of 16 nm were obtained by UV-NIL with a high TFP fraction (>66%) in the TFP/CTFP mixed gas atmosphere.

A cellulose derivative mold is used in imprint lithography and possesses great gas permeability. The gas permeable mold enables the minimization of the pattern failure caused by the accumulation of gas generated from imprinted material. This study aims to introduce a cellulose-based gas permeable mold for patterning UV-curable resin containing a volatile solvent. The measurement of the contact angles of the mold surface, dissolution test for the volatile solvent, and imprint lithography showed that the gas permeable mold has great imprinting repeatability and solvent resistance. We expect that imprint lithography using the gas permeable mold derived from the cellulose and materials containing volatile solvent will enable pattern failure reduction, repeatable imprinting, and decrease in the viscosity of the imprinted material.

A simple fabrication process is developed for self-standing resin films with well-defined through-holes by use of imprint technology. Polyvinyl alcohol film, which can be dissolved in water, is used as a sacrificial film. A commercial bi-layer film sheet, where polyvinyl alcohol (PVA) film is laminated on polyethylene terephthalate (PET) film, is used. A mold pattern is directly transferred to the PVA film in the bi-layer film sheet, and polystyrene (PS) resin is coated on the patterned PVA film. The PVA sacrificial film is removed in water. A defect free PS self-standing film of 0.7 μm in thickness can be obtained in the fixing frame with 5 mm diameter hollow. Through-holes of 2.5 μm square are successfully fabricated in the PS self-standing film.

Moth-eye-structure replica mold was fabricated from a glassy carbon master mold by UV-NIL. New UV curable resin with high hardness and antifouling property was used. The moth-eye-structure was duplicated from the replica mold by use conventional UV curable resin for UV-NIL. Compared with the replica mold by use of a conventional release-agent-free UV curable resin, the moth-eye-structure of new replica mold had superior imprint durability. The reflectance of the imprinted film was below 1% for the 350th imprint. It was that the antifouling property was very important for prolonging life time of replica mold.

Displays such as smartphones and personal computers suffer from deterioration in contrast due to reflection from fluorescent lamps and sunlight, and deterioration in visibility from scratches and fingerprints. There is a need for high-performance antireflection films. To realize such an antireflection film, we focused on the moth eye structure. In this study, an Anti-reflection structure (ARS) film was fabricated with ultraviolet nanoimprint lithography using the newly developed UV curable resin. The ARS film was subjected to scratch testing using steel wool. The change in shape, optical properties and antifouling properties were evaluated. The reflectance of the ARS film was about 0.4%, and the transmittance was over 90%. Contact angle measurements were used to evaluate the antifouling properties of the ARS film. The contact angle and sliding angle were >150° and 12° after the 30th scratch test, respectively.

Towards realistic adoption of EUV technology, material/process induced defect must be considerable problem. Several excellent studies have been introduced before and it mainly focused on the relation between defect number and pattern size and pattern pitch. Unfortunately, the study related defect transfer behavior have not been quite few, despite defect inspection is executed through top-down SEM.

 In this study, latent defect on via hole pattern, especially, the behavior of invisible hole around bottom area was focused on and we tied to clarify the exist of hidden missing defect utilizing unique RIE technique in hole image transfer onto under layer of resist film.

The stochastic defect generation such as pinching and bridging is a serious concern in extreme ultraviolet (EUV) lithography. The resolution blur (caused by secondary electrons) as well as the shot noise of EUV photons is considered to affect the stochastic defect generation. In this study, the relationship between resolution blur and stochastic defect generation in chemically amplified resists was investigated assuming two virtual sensitization mechanisms to clarify the effects of resolution blur. For the non-sequential radiative model, the increase of quantum efficiency from 2 to 4 is considered to be effective for the sensitivity enhancement, when the sensitization distance is shorter than 3 nm.

As the industry looks to extend single-expose extreme ultraviolet (EUV) lithography, stochastic effects become a significant concern to enable yield. Multiple previously-published reports have shown a strong tradeoff between resist sensitivity and observed stochastic defectivity. However, the limits of this trade-off between improving stochastics-related defects with a higher dose resist remains to be understood. How strongly does the resist formulation itself contribute to stochastics, or is it a purely dose-driven effect? Due to the thickness decrease in the patterning stack, the interfacial effects of the resist and hardmask films play a dominant factor in the material stochastics. This offers an opportunity to think differently about underlayer design for sub-32nm pitch patterning. The choice of hardmask can be used to modulate post-litho defectivity to mitigate the stochastics effects and enable more efficient pattern transfer. This paper will address multiple approaches to improving the materials stochastics through resist component optimization and hardmask film development. The defectivity at post-exposure and post-etch are correlated to electrical yield to validate the evaluation. The relative merits of patterning a chemically amplified organic resist directly on an inorganic hardmask or having different types of organic adhesion promoters as an intermediate layer will be also be presented.

Considering the scenario that polymer-based resists will possibly be struggling to satisfy all performance criteria for high volume manufacturing imposed by high power sources and high-NA imaging, it seemed necessary to introduce new materials for EUV lithography. To that end, nanometer scale metal clusters, originally designed to be building units of a metal-organic framework, were introduced and tested as metal-based resists. In the work herein, we wish to report all the progress that has been achieved in the patterning performance, focusing mainly on 32 nm and 44 nm pitch 1:1 lines and space pattern.