神田 一浩

The effects of thermal annealing of W incorporated diamond-like carbon (W-DLC) films fabricated with focused ion beam chemical vapor deposition (FIB-CVD) were investigated using X-ray absorption fine structure near the carbon K-edge (C-K NEXAFS) and the combination of Rutherford backscattering (RBS) and elastic recoil detection analysis (ERDA). W-DLC films were annealed for 32 h at temperatures, T_{\text{a } }, between 673 and 1073 K. Comparing the T_{\text{a } } dependences of Ga and H contents obtained from RBS-ERDA and the \mathrm{sp}^{2}/(\mathrm{sp}^{2} + \mathrm{sp}^{3}) ratios from C-K NEXAFS, it was found that even a trace amount of W incorporation into DLC films fabricated by Ga+ FIB-CVD may cause a significant \mathrm{sp}^{3} \rightarrow \mathrm{sp}^{2} structural change.

The deposition yield and physical properties of carbon films fabricated by focused-ion-beam (FIB) chemical vapor deposition were examined using several ion beam species of hydrogen, helium, xenon, and gallium. A gas-FIB was generated using an inductively coupled plasma ion source. It was found that the deposition yield is proportional to the total stopping power of the beam that penetrates into the carbon film. The physical properties of the carbon films deposited using gas-FIB are similar to those of films deposited using Ga-FIB, except for the Young's modulus.

A new room-temperature imprinting method was developed using liquid-phase hydrogen silsesquioxane (HSQ) with a hard poly(dimethylsiloxane) (h-PDMS) mold. The simultaneous imprinting of arbitrary patterns including both submicron and greater than 100 μm patterns on a 4-in. wafer were replicated at room-temperature and a low pressure with high throughput, because the solvent in HSQ gradually evaporated through the pores of the h-PDMS mold. A bilayer structure was successfully fabricated using as HSQ pattern as an etching mask without removing the residual layer.

The direct patterning of low-dielectric constant (low-$k$) materials via nanoimprint lithography (NIL) has the potential to simplify fabrication processes and significantly reduce the manufacturing costs of semiconductor devices. It is known that a low $k$ is realized by introducing a large number of nanoscale pores into a material. We demonstrated nanoimprinting on a sol–gel low-$k$ material ($k\sim 2.0$) formed using methyl silicate as a siloxane oligomer source and surfactants as a pore template. As a result, 200-nm-linewidth mold patterns were successfully transferred onto the sol–gel low-$k$ material by thermal nanoimprinting at 200 °C. However, pattern shrinkage was observed. The imprinted pattern linewidth was 180 nm. We assumed from the Fourier transform infrared spectroscopy (FT-IR) spectra of the sol–gel film before and after baking that the pattern shrinkage was induced by the condensation reaction.

The mechanical characteristics of iron-containing nanosprings (Fe-containing nanosprings) fabricated by focused-ion-beam chemical vapor deposition (FIB-CVD) using a ferrocene (C10H10Fe) source gas were investigated. The shear and Young's moduli were 34 and 92 GPa, respectively. We also evaluated the annealing effect of Fe-containing nanosprings and observed a droplet containing Fe and Ga on the nanospring after annealing at 600 °C. The spring constant rapidly decreased after annealing at 600 °C. By scanning electron microscopy energy–dispersive X-ray spectroscopy (SEM–EDX) and transmission electron microscopy energy–dispersive X-ray spectroscopy (TEM–EDX) line analysis, it was confirmed that the decrease in the spring constant was due to Ga removal.

The desorption processes of H and Ga from diamond-like carbon (DLC) film synthesized by focused-ion-beam chemical vapor deposition (FIB-CVD) were investigated by elementary analysis and local structure analysis after heat treatment under various conditions. The elementary composition of FIB-CVD DLC film was determined using a combination of Rutherford backscattering spectra and elastic recoil detection analysis spectra. Local structure analysis was performed by the measurement of near-edge X-ray absorption fine structure using synchrotron radiation. Desorption of H from FIB-CVD DLC film by heat treatment was found to comprise two types of process. One is the local graphitization along paths, where residual Ga atoms move by annealing. In this process, Ga acts as a catalyst for the graphitization of DLC. The other process is derived from the graphitization of the whole DLC film by heat, regardless of Ga. In this process, the sp2 content increases considerably.

We performed a nanostructure analysis of diamond-like carbon (DLC) nanowires used to compose nanosprings fabricated by focused-ion-beam chemical vapor deposition (FIB-CVD). The DLC nanowires of the as-grown nanosprings had elastic double structures, in which a 50-nm-diameter core containing 3-at. % gallium (Ga) in addition to carbon (C) was enclosed in an outer 25-nm-wide DLC shell. The Young's modulus of the core was 322 GPa, approximately 12 times that (26 GPa) of the DLC shell. Energy dispersion X-ray spectroscopy (EDX) revealed that the C densities of the core and the shell were similar, indicating that the density of the core was higher than that of the shell owing to the incorporation of Ga into the core. However, the core density was approximately halved by 800 °C annealing. This is attributed to the vaporization of Ga and the movement of C from the core to the shell.

Nanoimprint lithography (NIL) is very useful for mass-producing nanostructure devices at a low cost and a high throughput. To avoid the adhesion of replication materials, NIL molds are usually coated with an antisticking fluorinated self-assembled monolayer. In this study, we used a fluorinated plasma chemical vapor deposition film as the antisticking layer. First, we formed a CHF3 plasma chemical vapor deposition (CVD) film on SiO2/Si and quartz molds and carried out thermal and UV nanoimprint using these molds. However, the film was removed from these molds. We found that the proposed method can solve this problem. We irradiated plasma using a gas mixture of CHF3 and O2 as the source gas onto SiO2/Si and quartz molds. As imprinting results, the patterns were successfully imprinted onto the resins without the removal of the plasma CVD film. In addition, we were able to carry out 100 times of repeated nanoimprinting using the plasma-CVD-film-coated SiO2/Si mold.

Room temperature nanoimprint lithography (RT-NIL) is a simpler process than thermal and UV NIL because it can be carried out without a resist thermal cycle and UV exposure. A fluorinated self-assembled monolayer (F-SAM) is mainly used as an antisticking layer. However, the F-SAM deteriorates due to repeated nanoimprinting. To prevent the F-SAM coating on the NIL mold from deteriorating, we propose a new imprinting technique using release-agent spray-coated hydrogen silsesquioxane (RASC-HSQ). We carried out RT-NIL onto it using a mold without F-SAM. The pattern was successfully imprinted on the resin without any signs of adhesion.

The effect of annealing on implanted Ga of diamond-like carbon (DLC) films on Si substrates fabricated by focused-ion-beam chemical vapor deposition (FIB-CVD) was investigated. Thermal desorption spectroscopy showed two Ga+ peaks at 470 and 630 °C. These temperatures agree with the results of energy-dispersive X-ray diffraction analysis of Ga concentration in the film. Cross-sectional transmission microscopy revealed changes in the structure of the DLC film at each temperature. At approximately 400 °C, the Ga in the film migrated to the surface and desorbed. Above 600 °C, the Si in the DLC layer near the damaged Si substrate interface recrystallized. These results can be applied to enable deliberate control of the mechanical properties of DLC films fabricated by FIB-CVD.

In nanoimprint lithography (NIL), molds are in direct contact with replication materials. Furthermore, the glass transition temperature is around 100–200 °C in thermal NIL. We examined the temperature dependence of a release effect for the antisticking layer of a self-assembled monolayer with a fluoropolymer by scanning probe microscopy (SPM). We measured the contact angle and frictional force of the antisticking layer with and without annealing. The contact angle decreases and the frictional force increases at annealing temperatures greater than 500 °C. We analyzed the chemical composition of the antisticking layer with and without annealing by X-ray photoelectron spectroscopy (XPS). From the obtained measurement results, the CF3 and CF2 peaks of the antisticking layer disappeared after annealing at temperatures greater than 500 °C. These results show that the antisticking layer annealed at temperatures less than 500 °C has a sufficient release effect.

The effects of annealing on the material characteristics of a diamond-like carbon (DLC) thin film fabricated by focused-ion-beam chemical vapor deposition (FIB-CVD) were investigated. The elementary analysis, using Rutherford backscattering spectrometry and elastic recoil detection analysis, and measurement of hardness and Young's modulus, using a nanoindentation technique, were performed on the FIB-CVD DLC thin film by annealing for 1 h in the temperature range from room temperature to 1273 K. Elementary analysis indicated that the Ga content in the FIB-CVD DLC film used as an ion source began to decrease considerably at 523 K and the H content also began to decrease at 773 K. On the other hand, the hardness and Young's modulus of the FIB-CVD DLC film were found to decrease beyond 773 K. This decrease in hardness is ascribed to the variation in H content rather than in Ga content in the film.

UV-nanoimprint lithography (NIL) has the potentiality to enable fabrication of nanostructures with high-throughput and low cost. The template is a key element in UV-NIL. Template patterns are directly transferred into the replicated materials. A repair technique is indispensable for UV-NIL template fabrication. However, only a few reports have appeared on the repair of UV-NIL templates. In this study, program protrusion and hollow defects on UV-NIL templates have been repaired by focused-ion-beam (FIB) etching and SiOx chemical vapor deposition (CVD) using tetraethoxysilane as a source gas. The imprinted line patterns were successfully replicated by UV-NIL using the repaired templates. Moreover, it has been confirmed that FIB etching and CVD can be applied to repair 30-nm defects on quartz templates.

Materials deposited by focused-ion-beam chemical vapor deposition (FIB-CVD) have numerous interesting material characteristics. They contain gallium (Ga) because Ga is implanted by Ga+ FIB irradiation. Atomic ratios of the diamond-like carbon (DLC) deposited using phenanthrene (C14H10) as a gas source for FIB-CVD has the ratio of $\text{C} : \text{Ga} = 95 : 5$. And, It is also noted that the incorporated Ga in DLC is again segregated from DLC by annealing treatment. In this study, we found that Ga became agglomerated and was separated out from DLC by annealing treatment. Furthermore, Ga was passed out preferentially through the structural defect onto the DLC surface. Furthermore, the eduction position control of Ga sphere could be achieved using the via hole fabricated on the nanostructure by FIB-etching. This technique is utilizable for the formation of of junctions, such as a nano-bumps, to combine nanoelectromechanical devices.

Structure of the corrosion product films, which formed on hot-dip Zn-0.2%Al, Zn-5%Al and Zn-55%Al coatings in the early stages of corrosion reaction under the presence of NaCl particles, have been investigated by means of photoemission spectroscopy using synchrotron radiation and Al-Kα radiation. As a result, it is found that the surface compound of initial oxide film on Zn-Al coating changes from zinc oxide to aluminum oxide with increasing Al content, and that the structure depends on Al content. Additionally, the dominant compound of 1 nm or less in depth from the surface of corrosion products is seen to be different from that of 4 nm or less in depth. The corrosion resistance of Zn-Al coating is considered to be attributed to the depth profile of corrosion products on coating.

It is necessary to manipulate and analyze single cells and organelles with high accuracy for a deeper understanding of their biological phenomena. For this purpose, bio nano-tools are very useful. We fabricated a bio nano-sensing probe by using focused-ion-beam chemical vapor deposition (FIB-CVD) and evaluated it using a cell of an Egeria densa leaf. We found that the probe functions as a measurement electrode. This indicates that the bio nano-sensing probe is useful for single organelle analyses.

Diamond-like carbon (DLC) deposited by focused-ion-beam chemical vapor deposition (FIB-CVD) contains gallium (Ga) when a Ga ion beam is used. Therefore, DLC deposited by FIB-CVD (FIB-DLC) has specific material characteristics that differ from those of typical DLC. In this study, FIB-DLC's annealing-temperature dependence of field emission properties, work functions, and surface conditions were measured to understand its material characteristics. The results show that Ga incorporation is required in order to obtain a sufficient electric conductivity for the field emission. Furthermore, we found that the work function is increased by the graphitization of the FIB-DLC surface caused by the annealing treatment.