We tried to understand major impacted factor induced missing via defect as important challenge in EUV process and figure out favorable solution to avoid fundamental root cause. Main focal point in this study was interaction between resist film and surface condition of under-layer. As the result, it was found that higher polarity under layer has capability to enhance de-scum effect with NTD type resist combination. Opposite trend between exposed/unexposed region is ideal condition for resist scum removal without pattern peeling and its condition was achieved under NTD type resist with higher polar under-layer.

Inorganic molecular materials such as tin oxo cages are a promising generation of photoresists compatible with the demands of the recently developed Extreme UltraViolet (EUV) lithography technology. Therefore, a detailed understanding of the photon-induced reactions which occur in photoresists after exposure is important. We used XUV broadband laser pulses in the range of 25 – 40 eV from a table-top high-harmonic source to expose thin films of the tin oxo cage resist to shed light on some of the photo-induced chemistry via XUV absorption spectroscopy. During the exposure, the transmitted spectra were recorded and a noticeable absorbance decrease was observed in the resist. Dill parameters were extracted to quantify the XUV induced conversion and compared to EUV exposure results at 92 eV. Based on the absorption changes, we estimate that approximately 60% of tin-carbon bonds are cleaved at the end of the exposure.

To meet the requirements for EUV nanolithography, the semiconductor industry has drawn attention towards hybrid inorganic-organic based photoresists. However, the mechanisms responsible for the solubility switch in these materials are not well understood. In this work, UV/ VUV (4-14 eV) photon-induced fragmentations of Zn-based oxoclusters in the gas phase are investigated to study the fundamental reactivity of their cationic form. Irradiation of the parent cations results mainly in the ligand dissociation and fragmentation of the inorganic clusters at energies below the second ionization threshold (～12 eV). This ionization energy appears to be linked to the methacrylate ligand in the organic shell. We presume that this type of fragmentations can also occur when the oxoclusters are ionized in the thin film upon EUV irradiation.

Formation of an antenna-type sensor by laser direct writing based on graphene hybrid materials for humidity and chemical sensing properties was studied. A meander line shaped dipole antenna was prepared by laser direct writing on a graphene oxide (GO)-CuO NRs hybrid film. Resonance peaks were observed at around 4.7 and 5.89 GHz showing the dependence on relative humidity (RH). The humidity increase from RH38 to RH100 caused a resonance peak shift from 5.89 to 5.85 GHz accompanying the increase of return loss from -17.76 to -34.07 GHz. A spiral antenna sensor consisting of GO-coated copper-carbon hybrid showed the resonance band shift depending on the dielectric constant of a chemical compound.

We have investigated molecular motion and polarity of polyimide chain to developed novel low dielectric constant (Dk) and dissipation factor (Df) polyimides. We found that Df at 10-100 GHz corresponds molecular mobility at -150 to -50 ℃. To reduce the dielectric loss (=Df) at high frequency, restriction of molecular motion at low temperature was important. In addition, to reduce polar and flexible unit in the polyimide chain is also important to obtain low Dk and Df polyimide. We exploited these knowledge for development of low dielectric loss polyimide for RDL. As the result, we achieved 0.002 of loss tangent and 2.7 of dielectric constant respectively about novel polyimide. Those polyimides are patternable by alkaline wet etching with positive photo-resist development and by UV laser ablation method. We also have developed photo-definable low loss tangent polyimide by blending of photo active reagent. Lower insertion loss of microstrip line was observed by the novel low Df polyimide than by conventional photosensitive polyimide. Those low dielectric loss polyimides are suitable for insulator of FO-WLP, interposer and other RF applications for microelectronics.

In order to improve the performance and reliability of the package, the interlayer dielectric (Polymer) must not be delaminated and materials should not fracture due to thermal stresses during the operation or the manufacturing process, and the insulation performance between the wiring layers must not be decreased. The critical energy release rate (Gc) of the photosensitive polymer film (2-types of polyimides, polybenzoxazole, and phenolic resin) on the copper were evaluated by the Peel Test. We created material-specific master curves (time–temperature superposition) by considering the measurement results of the Peel Test at the Cu/Polymer interface and the mechanical properties of polymer. In addition, we calculated the energy release rate (G) from finite element analysis (FEA) in FOWLP structure. As a result, the new innovative reliability simulation was made possible by normalizing Gc and G. This study has made it possible to simulate the delamination possibility of Cu/Polymer interface at arbitrary temperatures and displacement rates from basic material data and FEA analysis of the FOWLP structure.

Microfluidic devices are used in many ways, including bioanalysis and chemical synthesis. Nevertheless, these devices have some issues, such as their susceptibility to bubble entrapment and impurities, and their necessity for high pressure to transport liquid as these devices consist of various closed tubes. To solve these problems, we have focused our research on a coastal animal, the wharf roach, which has open-type flow micro-passages composed of micro-blade arrays driven by surface free energy. Inspired by the microstructures, we fabricated a series of flow passages composed of micro-scaled epoxy blades on a silicon wafer through photolithography. The purpose of the present study was to control the liquid transport velocity and understand the liquid film thickness during transport, with the goal of manipulating liquid transport without external forces using the microstructures. The relationship between the interval of the blades and the liquid transport velocity was investigated. Furthermore, the variation of the liquid film thickness ratio with elapsed time was visualized using fluorescent dyes. As a result, we found that the liquid transport velocity was maximized when the blade height was high, and the cross-sectional shape between the two blades was square. Moreover, the interval in the vertical direction was narrow. In addition, it was clear that the liquid film of the water temporarily became thick near the three-phase contact line and the thin water film preceded the uniform thick water film. These findings are important for optimizing liquid transport in open-type microfluidic devices.

Nano- and micro-structures can be realized by using photofabrication, crystal growth, chemical deposition, etching and other methods. This variety of fabrication methods encourages the development of water-repellent surfaces from the viewpoint of biomimetics. Water striders have attracted interest in biomimetics because their water-repellency property makes it possible for them to live on water surfaces. Micro-hairs, which are present on the surface of the water strider’s legs, can maintain an air layer between the water surface and the legs, providing the repellency property. While there have been various studies which have considered a physical model of the water strider’s water-repellency property, no model has taken directly measured water strider leg-rowing force into account. Therefore, in this study, we proposed a physical model of a water strider using Laplace pressure, and then we considered directly measured leg-rowing force to verify the model. First, we considered the relationship between water pressure around the micro-hairs and the intersection of the surface of the micro-hairs and the water surface using our proposed model. We found that when the micro-hairs were in contact with the water surface and the air layer was maintained, the maximum Laplace pressure P_max was 35.2 kPa. This meant that if Laplace pressure exceeded 35.2 kPa, the water pressure caused by the rowing motion of the strider legs pushed water into the space between micro-hairs. Additionally, we calculated maximum water pressure P_L which was loaded around the surface of the water strider's leg by rowing of the leg. P_L was 546 Pa, and this value was significantly smaller than P_max. This meant that the water pressure did not push water into the space between the leg micro-hairs and the water strider’s legs maintained their water repellency when moving.

Soft actuators have been studied actively by many research groups for practical application of artificial muscles. Among them, magnetic soft actuators have been expected to play an active role in the future for a miniaturized actuator. Since it needs no rigid mechanical parts inside and the energy could be transmitted via space, it would be easier to be downsized. Various kinds of magnetic soft actuators, such as rubbers and gel, could be used for this magnetic actuator. In this work, we aimed to improve the strength and the toughness of soft material. We focused on an extremely tough gel material called double network gel, which is composed of a heterogeneous structure of hard gel and soft gel. Double network gel has high strength due to the heterogeneous structure of a hard gel and a soft gel, which has been expected to be used in medical fields such as artificial cartilage due to its high elasticity. We measured the mechanical properties of the gel produced under each production condition and determined appropriate production conditions, Furthermore, the feasibility as a soft actuator was carried out using a thin gel film in which magnetic particles were mixed with a gel and confirming the deformation when a magnetic field was applied.

In nature, there are living organisms that have functional properties with a special surface structure. The research has been widely conducted to apply the same functional properties by engineering the above structure. In this study, we focused on the hierarchical structure with high aspect ratio found in lotus leaves and Morpho butterfly scales. We chose Nano imprint lithography (NIL) as a method for fabricating the structures because of its advantages such as low cost and high accuracy. However, the conventional NIL only enables to transfer patterns perpendicular to work surface due to the necessity of mold release, so that we cannot obtain a hierarchical structure by NIL. Therefore, as a new process, we tried to form a hierarchical pattern by multi-step imprinting and to increase the aspect ratio by an in-plane compression method. In this paper, we quantitatively evaluated the interface pattern of each hierarchy.

The leaves of plants belonging to the Araceae family and to the Nelumbonaceae family, represented by the lotus leaf, are known to exhibit water repellency, a property attributed to a double roughness structure having nanostructures on the surface of the leaves. Past research efforts have examined biomimetic structures modeled on the structure of the lotus leaf. The present report presents the results of investigations of a lotus leaf structure transferred onto acrylic resin, made using a live plant as the original material instead of an engineered imitation. The results confirmed that the super water repellency derives from this structure.

Techniques have been developed for measuring orbital deviation by image measurement. In this method, the trajectory distortion is measured by measuring the coordinates of the center of gravity of the circle with a digital camera. However, due to the repeated train running, the surface of the recursive target for measurement becomes black due to dirt, and the position of the center of gravity of the circle cannot be accurately measured on the image. Dirt due to the deposits is an important issue, and a technique for protecting the surface of the target from dirt is desired. In this study, we develop a target antifouling sheet using a metamaterial technology that imitates a snail shell and has an oil-repellent effect and verifies the effect.

We are now beginning to see the application of extreme ultraviolet (EUV) lithography to the mass production of 7 nm node logic devices, primarily for smartphones. This lithography technology currently attracts the most interests due to its expected use in upcoming mass production of 5nm node and beyond for semiconductor devices. The development of EUV resists are one of the key research areas. However, EUV exposure instruments are extremely costly, and there are currently no tools that can be used for resist development. To promote the development of EUV resists, we investigated an evaluation method based on EB exposure for EUV resist. Due to similar exposure reaction mechanisms to EUV exposure, EB exposure offers a practical alternative. This paper examines the use of EB exposure simulations to advance EUV resist development.

The semiconductor industry plans to keep fabricating integrated circuits, progressively decreasing there features size, by employing extreme ultraviolet lithography (EUVL). With this method, new designs and concepts for photoresist materials need to be conceived. In this work, we explore an alternative concept to the classic photoresist material by using an organic self-assembled monolayer (SAM) on a gold substrate. The monolayer, composed of a richly fluorinated thiol sensitive to low-energy electrons, is adsorbed on the Au substrate which acts as main EUV-absorber and as the source of photoelectrons and secondary electrons. We investigate the stability of the SAM adsorbed on gold towards EUV radiation by means of in-situ photoelectron spectroscopy. The photoelectron spectra indicate that the monolayer attenuates a significant amount of primary electrons generated in the gold layer. The spectral evolution upon EUV irradiation indicates that the SAM loses a significant amount of its initial fluorine content (ca. 40% at 200 mJ/cm²). We attribute these chemical changes mostly to the interaction with the electrons generated in the thiol/Au system.

The extensibility and elasticity of biological soft tissues such as skins, tendons, and ligaments are attributable to the quality and quantity of elastin fibers. Elastin is a representative biological polymeric fiber in the extracellular matrix of the soft tissues. The pure molecular solution of elastin is hardly extracted due to its insolubility. From this reason, many basic characteristics of elastin have not been fully elucidated not only in the area of biochemistry and molecular biology but also in that of biomechanics. The purpose of the present study was to develop biomimetic materials which include elastin ingredients for the maintenance and improvement of the skin extensibility during the wound healing. We formed the elastin-based materials whose elastic moduli were similar with those of skins. These materials were integrated with healing tissues of skin damage. These results indicate that the biomimetic materials containing elastin ingredients are useful for regenerative medicine to effectively repair skin damage.

Thin film transistors (TFTs) are the basis for current AMOLED display arrays. For next- generation displays, higher resolution and cost-effective manufacturing of panels is adamant. The current benchmark patterning method in the display industry is photolithography. Here, we propose the use of a hybrid approach of nanoimprint lithography and conventional FPD processing for the realization of high-resolution display backplanes. We demonstrate the realization of sub-micron amorphous oxide semiconductor TFTs with multi-level nanoimprint lithography in order to decrease the number of patterning steps in display manufacturing. Top-gate self-aligned a-IGZO TFTs are realized with performance comparable to benchmark photolithography-based TFTs.

The accuracy of a numerical modeling method for UV imprint processes to simulate the UV resin deformation due to UV shrinkage was evaluated. Typical UV resins induce volumetric shrinkage by several percent after UV curing. The curing shrinkage deforms the pattern shape and could be a significant issue in UV imprint for high-precision pattern moldings such as optical device patterning. Taking notice of the analogy between UV imprint and thermal imprint, the modeling method introduces the idea of “virtual temperature” to express the UV reaction progress. Accordingly, the curing/shrinkage of UV resin can be treated as the solidification /contraction of thermo-plastic resin modeled as a thermo- viscoelastic material. A validation analysis for a micromirror array patterning with the shift in the demolding time reveals that the modeling method can qualitatively predict the final shape of surface curves varied with the demolding time.