神田 一浩

This is the first report on the precise elemental composition of a diamond-like carbon (DLC) thin film fabricated by focused-ion-beam chemical vapor deposition (FIB-CVD). The atomic fraction of the FIB-CVD DLC film has been determined to be $\text{C}:\text{Ga}:\text{H}=87.4:3.6:9.0$ at. % using Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA). The hydrogen content of the FIB-CVD DLC film was lower than that of DLC films formed using other CVD methods.

The annealing effect on the local structure of diamond-like carbon (DLC) formed by Ga+ focused-ion-beam chemical vapor deposition (FIB-CVD) was investigated by the incidence angle-dependent measurement of the C K-edge near edge X-ray absorption fine structure (NEXAFS) from 0 to 60°. The peak intensity corresponding to the resonance transition of $\text{1s} \rightarrow \sigma^{*}$ originating from carbon–gallium bonding markedly increased with incidence angle in the spectra of a FIB-CVD DLC film annealed at 400 °C. This angle dependency was attributable to the movement of residual Ga atoms from the bottom to the neighboring surface of the FIB-CVD DLC film.

The surface property of fluorinated diamond-like carbon (F-DLC) thin film, which is expected to be a new antisticking layer of nanoimprint mold, was evaluated with reference to the commercial diamond-like carbon (DLC) thin film formed by radio-frequency (RF) plasma chemical vapor deposition (CVD) and the fluorinated self-assembled monolayer (SAM). From the measurement of X-ray photoelectron spectrum (XPS), the surface of the F-DLC thin film was found to be overspread with hydrophobic CFx components. In addition, the durability of the F-DLC thin film was evaluated by the contact angle measurement of a water drop against repeating times of the thermal imprint process. After over 100 times of imprinting, the contact angles of the F-DLC thin film were almost kept constant with the initial value and a fine replicated pattern was obtained. From these results, the F-DLC thin film was found to be suitable as a novel antisticking layer of the thermal nanoimprint mold.

We fabricated a silicon dioxide-based vacuum microcapsule using focused-ion-beam chemical-vapor-deposition (FIB-CVD) to realize three high-performance vacuum electronic micro-devices: a diode, a triode, and a sensor. We measured the electrical characteristics of diamond-like carbon (DLC) and silicon dioxide (SiO2) deposited using FIB-CVD, and found that they had characteristics that are useful in conductors and insulators, respectively, used in vacuum micro-device fabrication. Furthermore, to evaluate the inner vacuum of a microcapsule, a diode with a microcapsule was fabricated using FIB-CVD. By measuring the current–voltage ($I$–$V$) characteristics of the diode, it was demonstrated that the inner vacuum of the microcapsule was maintained. This result indicates that various high-performance three-dimensional vacuum micro-devices can be fabricated using FIB-CVD on any surface.

Electronic structures of oxide films on hot-dipped Zn-0.2%Al, Zn-5%Al, and Zn-55%Al coated steel sheets have been investigated by means of the synchrotron radiation photoemission spectroscopy and compared with those of Zn and Al pure metal sheets. The oxide films were prepared by 85 hour exposure in air saturated with water vapor at 323K. The oxide film on Zn-0.2%Al had the same photoemission spectrum as the pure Zn metal, while Zn-5%Al and Zn-55%Al were similar to the pure Al in the form of photoemission spectrum. It was found that the electronic structure of the oxide films and the depth profile of the ratio of zinc oxide to aluminum oxide are varied with the ratio of Zn to Al in the alloys. The corrosion resistance of Zn-Al alloys is discussed being related to the electronic structure of the oxide films.

The surface modification of poly(tetrafluoroethylene) (PTFE) sheet was carried out by exposing the sheet to synchrotron radiation (SR) ranging 50–1000 eV under O2, H2O and CH3OH gas atmospheres. The wettability of the PTFE surface was found to increase with SR dose under each gas atmosphere. The rate of increase in the wettability of the PTFE surface exposed to SR under the O2 gas atmosphere was higher than those of the PTFE surfaces exposed to SR under the other gas atmospheres. The decrease in the amount of –CF2 component and the presence of –C=O and –OH components were observed on a hydrophilic PTFE surface.

Mechanically hard amorphous carbon nitride films were prepared by a combination of radio frequency (RF) bias voltage applied to a substrate and chemical vapor deposition using a decomposition reaction of BrCN with a microwave discharge flow of Ar. A pulsed operation of the negative RF bias voltage ($-V_{\text{RF } }$) was applied to avoid excess sputtering of the film. The $[\text{N}]/([\text{N}]+[\text{C}])$ ratios of the films were ${\approx}0.5$ irrespective of the application of $-V_{\text{RF } }$. The maximum hardness was $36\pm 10$ GPa for the film obtained under the conditions of $-V_{\text{RF } }=100$ V, a pulse period of 1000 s, and a pulse-on time of 800 s. According to the IR spectra, the intensity of the stretching vibration of the C–N bond was increased by the application of $-V_{\text{RF } }$. The Raman spectra showed increases in the relative intensity and width of the D-band. From these observations, the mechanism of film hardening when $-V_{\text{RF } }$ is applied was discussed.

Fluorinated diamond-like carbon (F-DLC) has recently been applied as an antisticking layer on nanoimprint molds for semipermanent use, replacing the self-assembled monolayer currently used. An SiO2/Si mold was successfully coated with an F-DLC thin layer by chemical vapor deposition (CVD). The measured water contact angle of the F-DLC surface was 103°, which is 30° higher than that of the DLC surface. This value indicates the adequacy of F-DLC as an antisticking layer. Moreover, an F-DLC film had a high hardness of 24 GPa, similar to that of a DLC film (26 GPa). AZ resist patterns of 150 nm linewidth and 350 nm pitch were successfully obtained by thermal nanoimprinting using an F-DLC-coated mold. Finally, after repeating the imprinting for more than 100 times, the initial water contact angle of 103° for the surface of the F-DLC-coated mold was maintained.

The control of wettability on a diamond-like carbon (DLC) surface was carried out by exposure to synchrotron radiation (SR) in the soft X-ray region under the perfluorohexane (C6F14) gas atmosphere. It was found that the contact angle of a water drop against the DLC surface increased with SR dose; in particular, it increased from 73 to 91° by the SR exposure of a 1 mA$\cdot$h dose. The formation of the hydrophobic DLC surface was attributable to the fluorine-functional groups that existed on the DLC surface after SR exposure under the C6F14 gas atmosphere.

We carried out the field-emission characterization of materials, such as diamond-like carbon (DLC), W, and Fe, deposited by focused-ion-beam chemical vapor deposition (FIB-CVD) to develop a field emitter to be used as a nano-tool for spot deposition. As a result, the threshold voltage of the field emission from the DLC was lower than those from the W and Fe. In addition, we measured the work functions of these materials using photoelectron spectroscopy and found that DLC has a low work function. Furthermore, a field emitter with a DLC tip as a cold cathode was fabricated on a glass capillary, because it was found to be able to emit electrons from the DLC using a low voltage. We also confirmed that electrons were emitted from a DLC tip fabricated by FIB-CVD.

High-performance nanotools are very important for nanoscale operation and analysis in the various research studies. To improve the performance of these tools, it is necessary to make three-dimensional (3-D) nano structure devices. We fabricated a 3-D electrostatic nanomanipulator with SiO2/DLC heterostructure by focused-ion-beam chemical vapor deposition (FIB-CVD). In this article, we report on the fabrication and movement check of the 3-D electrostatic nanomanipulator.

Focused-ion-beam chemical vapor deposition (FIB-CVD) is an excellent technology for forming a free-space-nanowiring. At 295 K the electrical resistivity of a free-space-nanowiring made using phenanthrene as the source gas was $1\times 10^{2}$ $\Omega$ cm. Adding tungsten hexacarbonyl to the phenanthrene reduced the electrical resistivity to $2\times 10^{-2}$ $\Omega$ cm. The nanomechanical switch composed of a coil and a nanowiring has been fabricated by using free-space-nanowiring fabrication technology, and its operation has been confirmed by applying a voltage.

Photoexcitation process leading to a variation in the wettability of a poly(tetrafluoroethylene) (PTFE) surface induced by synchrotron radiation (SR) exposure in the soft X-ray region was investigated. It was found that two types of photoexcitation, that is, the formations of a hydrophobic surface and a hydrophilic surface, proceed on the PTFE surface with the exposure to SR. The formation rate of the hydrophobic surface strongly depended on substrate temperature.

The Morpho-butterfly wing reflects interfered brilliant blue, which originates from nanostructures on its scales, for any incidence angle of white light. We have, for the first time, fabricated a Morpho-butterfly-scale quasi-structure using focused-ion-beam chemical-vapor-deposition (FIB-CVD) and observed brilliant blue reflection from this quasi-structure with an optical microscope. We measured the reflection from real Morpho-butterfly scales and from the quasi-structure with a photonic multi-channel spectral analyzer system. The reflection spectra of the quasi-structure were very similar to those of Morpho-butterfly scales.

Nanoimprint lithography (NIL) Si molds with protrusion- and hollow-defects were repaired by Ga+ focused-ion-beam (FIB) direct etching and chemical-vapor-deposition (CVD). The usability of the repaired mold was confirmed by carrying out NIL on poly(methylmethacrylate) (PMMA). After the NIL process, Ga grains appeared on the etching-repaired mold, which was confirmed by scanning electron microscopy-energy dispersive spectrometry (SEM-EDS). The thresholds of ion dose and annealing temperature for Ga grain appearance are studied.

The three-dimensional (3D) nanostructure fabrication technology using focused ion beam chemical vapor deposition (FIB-CVD) is very effective for highly efficient 3D nanomechanical device fabrication. We can fabricate 3D nanostructure easily and freely with this fabrication technology using FIB-CVD. Here, we demonstrate the fabrication of various 3-D nano-electrostatic actuators and manipulators on a glass capillary by 30 keV Ga+ focused-ion-beam-assisted deposition with phenanthrene vapor as a precursor, and the operation of these actuators and manipulators by applying voltage onto a Au-coated glass capillary under an optical microscope is shown. Furthermore, the structural characteristics and functionalities of them are described in this paper.