Studies have been carried out on developing a method for improving EUV resist sensitivity by enhancing EUV light absorption through the addition of metals having high EUV light absorption to the resist polymer in order to increase secondary electron emission, thereby enhancing PAG reactivity and improving acid generation efficiency^(1)-(3). To confirm whether the addition of metals having high EUV light absorption actually does enhance sensitivity, study efforts included transmittance measurements and sensitivity evaluations of resist samples doped with ZrO₂ or TeO₂ nanoparticles, which have low and high EUV light absorption, respectively, in molar quantities of 0-2 relative to PAG. The samples were subjected to EUV exposure at the NewSUBARU synchrotron radiation facility. While the ZrO₂-doped resist showed no evident enhancement of sensitivity or transmittance, the TeO₂-doped resist showed enhancement in both properties. Based on these results, we confirmed that the addition of metals having high EUV light absorption to the EUV resist enhances its EUV light absorption and increases secondary electron emission, thereby enhancing PAG reactivity and improving acid generation efficiency.

In order to investigate the effect of surface roughening due to laser irradiation in two-step thermochemical water-splitting with CeO₂ system, we irradiated reactive ceramics of CeO₂-NiO system and formed groove-like structures on the surface of these samples using the two types of lasers, such as a CW laser (λ=1070nm) and a nanosecond (Ns) pulsed-laser (λ=532nm). We observed structural and characteristic changes after laser irradiation and thermochemical cycling, and estimated the amount of the syngas (H₂ and O₂ gases) during thermochemical cycling. The following findings can be derived from the experimental results. (1) The surface of the samples irradiated by a CW laser became much smoother and its color changed from milky white to blue, while the sample surface after Ns pulsed-laser irradiation was almost the same as that before laser irradiation. (2) Glass-like material was observed on the surface of the sample after thermochemical cycling, and groove-like structures partly changed into melted-like structures. (3) The amount of the syngas from the all of the irradiated samples was markedly higher than that from the unirradiated samples only at the early stage of thermochemical cycling. This reduction after a few cycles would result from the sintering of CeO₂ samples under high temperature and from the separation of inorganic adhesive used as a binder. (4) Even though with lower surface area, the samples by Ns pulsed-laser irradiation emitted more H₂ gas than those of other samples, because they have no a melted-like and smooth surface.

A simple and low-cost projection exposure system was developed for printing large patterns with widths of 50-100 µm in thick resist films with a thickness of 100 µm. As a projection lens, a commercially available camera lens was used. The projection ratio was set to 1.0, and the calculated numerical aperture (NA) was 0.089. By setting the NA to such low value, a large depth of focus was guaranteed. In addition, side walls of resist patterns were controlled almost vertical by printing patterns under the largely defocused conditions. Using the exposure system and the above mentioned defocused exposure, flow path patterns with vertical side walls were precisely fabricated. It was demonstrated that the micro-mixers with the resist flow paths were successfully usable without leaks. It was discussed finally why such patterns with vertical side walls were desirably obtained.

For evaluation of defects on extreme ultraviolet (EUV) masks at the blank state of manufacturing, we developed a micro coherent EUV scatterometry microscope (micro-CSM). The illumination source is coherent EUV light with a 140-nm focus diameter on the defect using a Fresnel zoneplate. This system directly observes the reflection and diffraction signals from a phase defect. The phase and the intensity image of the defect is reconstructed with the diffraction images using ptychography, which is an algorithm of the coherent diffraction imaging. We observed programmed phase defect on a blank EUV mask. Phase distributions of these programmed defect were well reconstructed quantitatively. We also observed actual defects which was inspected by the ABI tool. Actual amplitude defect and phase defect images were reconstructed with intensity and phase contrast. The reconstructed image indicated the defect type of these defect. The micro-CSM is very powerful tool to evaluate an EUV phase defect.

We demonstrated that a Ti-6Al-4V (Ti64) plate, which is clinically applied for artificial bone in human body because of their light and biocompatibility, was fabricated by selective laser melting (SLM) in vacuum. The chamber's pressure was set to 1.0×10^-2 Pa to prevent the Ti64 powder from oxidizing. The base-plate of the powder bed was vertically dropped in determined steps, and Ti64 powder supplied from the powder feeder was then smoothed by a roller on top of the powder bed. The single-mode fiber laser irradiated through 3-axis Galvano mirror and melted the powder to make a molten pool in order to form 2D metallic structures. In order to investigate the laser melting and solidification dynamics, a process of Ti64 plate fabrication was captured by high speed video camera. It was also determined that crystal orientation was evaluated with X-ray diffraction (XRD). From XRD analysis, it was recorded from the powder peaks of α (1011), α (0002), α (1010), and α (1012) that the crystal orientation is composed mainly of martensitic alpha by XRD analysis. Diffraction peaks corresponding to β (110) were detected in vacuum SLM processed samples.

We analyzed the Hablanian plot results of the welding data using only fiber lasers for stainless steel (SUS304). These data were a part of those in our previous article. We discussed the following: (1) two types of unique behavior confirmed in our previous article, (2) a difference between Hablanian plot and Swift's model, and (3) the prediction of a penetration depth using Hablanian plot with pulsed lasers. The following findings could be derived. (1) Micro welding results located above the standard fitting curve for welding data using CW fiber lasers. This would result from the use of long-focus lenses. (2) The fitting curve for f_f = ∼300 mm was the closest to the standard fitting curve. (3) In the higher Vd/K and P/(θtk) regions, the experimentally obtained penetration depth was ∼20% of that without any losses of a laser energy. (4) In order to predict a penetration depth using pulsed lasers, we need to obtain the Hablanian-plotted fitting curves with the corresponding duty ratios.

The purpose of this study is to make a proposal for a simple and non-invasive irradiation positioning technique in the heavy particle beam therapy. For this purpose, we propose a method of using electric and ultrasonic multi imaging. Features of the proposed method, by simultaneous imaging of ultrasound and electric characteristics in the same space, with only ultrasound imaging is that changes in can not be found properties will be able to discover. This paper attempts to imaging of the tumor area by computer simulation in the model close to a living body. Furthermore, the diagnostic ultrasound system estimating the structure of the body, proposes a method of setting the initial value of the impedance imaging tailored to its composition, we report confirmed its usefulness.

Covering an electrode with a dielectric layer improves the performance of SF₆ gas-insulated systems. This time, the authors evaluated the influence of charge accumulation of the coated electrode surface on the breakdown characteristics and measured the charge amount on the coated electrode surface. Results of the breakdown voltage measurements showed that, without the charge elimination, both the absolute value and the dispersion of the breakdown voltages enlarged. On the other hand, the influence of the charge accumulation was not observed for the minimum breakdown voltages. By measuring the surface potential of the coated electrode, two results were obtained. First, as for negative voltage application, if the electric field of the coated electrode tip exceeded the critical ionization electric field of SF₆ gas, but breakdown did not occur, a positive surface potential was observed. On the other hand, if breakdown occurred, the surface potential hardly changed. Second, as for positive voltage application, if breakdown occurred, a negative surface potential was observed. On the other hand, if breakdown did not occur, the amount of the surface potential varied depending on the electrode system and the SF₆ gas pressure.

The influence of the carrier mobility and charge accumulation in interfacial layers on the deterioration of organic light-emitting diodes (OLEDs) was investigated. There was a relationship between the deterioration of the device characteristics and the electron mobility of the emissive layer and the electron transport layer. The samples with lower electron mobilities had less degradation, whereas the samples with higher electron mobilities had more significant degradation. We simultaneously observed a decrease in the maximum capacitance, C_max, of the OLEDs, implying that there was charge accumulation at the recombination zone in the vicinity of the emitting layer. Our study demonstrates that controlling the electron mobility in the electron transport layer is necessary to protect the device from accumulation or trapping of charges and deterioration of the luminance.

We have reported that a low temperature growth (LTG) technique is effective to expand the lower growth temperature region of c-axis orientated SmBa₂Cu₃O_y (SmBCO) thin films so far. However, BaHfO₃ (BHO)-doped SmBCO LTG-films show serious decrease of J_c at low magnetic field compared with conventional PLD-films. We investigated thickness dependence of SmBCO seed layers on LSAT single crystal. The result shows the seed layer is the cause of J_c decrease at low magnetic field due to flux line motion in the seed layer. In order to prevent the J_c decrease, we have tried to add Y₂O₃ in the seed layer on IBAD-MgO substrate. As a result, Sm-rich particles were formed in the seed layer, and those particles prevented flux line motion in the seed layer. After that, we measured the BHO-doped SmBCO films on Y₂O₃-doped seed layer at 77 K. As a result, the Y₂O₃-doped seed layer is effective at 77 K because the diameter of Sm-rich particle is about 17 nm which is larger than coherent length of 77 K in REBCO films. In summary, we improved J_c decrease at low magnetic field by adding the Y₂O₃ in the seed layer, and that film deposited by PLD-LTG technique showed high J_c at wide magnetic field.

A high-speed and high-sensitive eddy current testing (ECT) system was developed for the inspection of spring steel materials in manufacturing lines. The permeability distribution of the steel materials affects inspection results and the signal-to-noise (S/N) ratio decreases. Therefore, magnetizing the materials is required to reduce the magnetic noise. In this research, the spring steel materials that have artificial microcracks (29∼114 µm depth) were magnetized and inspected to evaluate detection performance of a developed ECT probe. It was confirmed that the probe is able to detect the 40 µm depth crack with the S/N ratio of 3 or more. The detectivity of pitting corrosions was evaluated for the consideration about applicability of the probe in natural flaws. In addition, the permeability distribution around the crack in the magnetic saturation ECT was clarified with a finite element method (FEM) analysis.

If powder of iron is included in the insulation of a polymer-insulated cable during its manufacturing process, breakdown or a water tree would be triggered from there. In this study, we mixed powder of iron into a sheet of low-density polyethylene and measured spatial distributions of absorption at terahertz (THz) frequencies. As a result, it has become clear that the absorption increases in the whole range from 0.5 to 5.0 THz at the places where the powder exists, even if the sheet is covered with an opaque carbon-black-loaded polyethylene sheet.