比田井 洋史

Chemical vapor deposition (CVD) is one of the most popular film deposition methods on solid substrates. We propose a new powder synthesis method utilizing CVD process, that uses a liquid instead of a solid as a substrate. The gas close to the liquid surface and or dissolved in the liquid was decomposed by laser irradiation and particles were synthesized. Water was used as a liquid, because of its large solubility. Diamond like carbon particles were synthesized by ArF excimer laser irradiation to the methane dissolved in water. Grain size of the particle synthesized from the gas close to the liquid surface was 50-200nm, and that from the gas dissolved in the water was 200-700nm. Grain size could be varied with laser power. Energy dispense spectroscopy (EDS) clarified that the powder mostly consisted of carbon, and oxygen and nitrogen could not detected. High resolution transmission electron microscope (HR-TEM) and electron diffraction revealed that the powder was composed of diamond like carbon (DLC) and multiwall carbon nanotube was grown on the DLC

In this paper, spherical surface molding of polymer using a liquid mold system is described. A liquid droplet has spherical surfaces at the liquid-liquid interface due to interfacial tension. The curvature of the spherical surface is determined by the degree of interfacial tension applied at each interface. Interfacial tension between some liquids was measured, and the shape of a photopolymer droplet between the liquids was calculated. Ultraviolet light was irradiated onto a photopolymer droplet located at the liquid-liquid interface, using a superhigh-pressure mercury lamp. Photopolymer droplets solidified and lens-shaped objects were produced. Cross sections of these objects were observed, and the curvatures of the spherical sufaces were found to correlate with the interfacial tension. A spherical solid was formed at a water/salt solution interface. The possibility of forming various spherical surfaces by exploiting liquid-liquid interfaces was revealed.

In this paper, hydrothermal reaction assisted laser process was suggested. Silicon nitride (Si_3N_4) and cubic boron nitride (cBN) were selected as ceramics. Argon ion laser was irradiated to them in water, steam, air, vacuum, argon, and oxygen. Threshold laser power that Si_3N_4 could be processed in water and steam was lower than that in other atmosphere. Removed depth of laser processed single crystal cBN was twice in water and six times in steam as deep as that in air. Hydrothermal reaction was certified by detection of hydrothermal products, such as ammonium and silica ion from Si_3N_4,ammonium and boric ion from cBN. Binder-less sintered cBN was also enhanced by processed in steam.

In this paper, a new, simple, high-speed method of selective, metal deposition on glass substrates is proposed. Metal powders, placed on a glass substrate were irradiated by an argon ion laser beam. Soda glass, Pyrex glass and silica glass were used, and aluminum and copper powders were chosen. Both metal powders could be deposited on all the glasses. Furthermore, silicon wafer, which placed on Pyrex glass substrate, could be bonded to glass by the similar method.

In this paper, a new method of selective deposition on glass substrates is proposed. Metal powders placed on a glass substrate are irradiated by a laser bam through the glass from the other side and consequently the powders are sintered on the glass substrates. Soda glass, Pyrex glass and silica glass were used as substrates from the viewpoint of their thermal properties, and stainless steel (SUS316L) powders with grain size of 7 μm and 60 μm were chosen. An Ar ion laser beam was used because glass is highly transparent. Fine metal powder was deposited on every glass substrate, and the size of the deposited metal powder was controllable from 120 μm to 840 μm in diameter, and from 45 μm to 330 μm in height by varying the laser power and irradiation time. In the experiment, changing the glass substrate revealed that the adherence of the metal powder was the strongest on the soda glass of all the glasses. Also varying atmosphere and powder size clarified that the metal powder adhered to glass better in air than in vacuum and with fine powder than coarse powder.

Solids and gases have widely studied in laser processing but there have not been so many reports about liquids applied to laser processing. Characteristics of liquids are as follows : liquid has high thermal conductivity, can suspend small particles and colloid, and dissolves gases. These characteristics suggest the possibility of using liquid as a substrate for film synthesis, surface-treating particles suspended in liquid and synthesizing small particles by excited gas dissolved in liquid by laser irradiation, respectively. This study focused on gases dissolved in liquid, so water was chosen as a liquid because of its large solubility, stability and high thermal conductivity. An ArF excimer laser was used because its wavelength is close to absorption edge of water. Firstly, the influence of the dissolved gas was studied and it is found that there is possibility of synthesizing substance in/on the water dissolving methane by laser irradiation. Secondly, synthesizing substance was tried. As a result, carbon films were obtained on the water by laser irradiation to the water from above. According to elementary analysis, solubility, Fourier transform infrared spectrometer, Raman spectrum and scanning electronic microscope, the films contain hydrogen and consist of small particles 30nm in diameter.

In this paper, a new, simple, high-speed method of selective metal deposition on glass substrates is proposed. The method is as follows: metal powder is placed on a glass substrate, then an argon ion laser is irradiated through the glass from the other side. Soda glass, Pyrex glass and silica glass were used as substrates, aluminum and copper powders, with grain sizes of 7.0 mum and 4.6 mum, respectively, were chosen. The beam of an argon ion laser (Coherent, DBW20) was used at 488nm wavelength, because the glasses have high transparency of visible light. Both aluminum and copper can be deposited on all the glasses. Aluminum deposited on the soda glass were 80 mum - 800 mum in width and 10 mum - 120 mum in height. The deposited aluminum and copper had high conductivity and resistances of 0.017Omega/mm - 0.64Omega/mm and 0.0014Omega/mm - 0.2Omega/mm, respectively.

Water was used as a substrate and carbon films were obtained from methane gas on the water by ArF excimer laser. The film was analyzed by a SEM, elementary analysis, Raman spectrum and FT-IR. Moreover synthesized position of the film was studied.