Shinzo Morita

Variable-focus liquid-filled optical lens

A variable-focus liquid-filled optical lens consists of a solid plate, a ring spacer, and an elastic film; a liquid fills this lens-shaped container. One varies the focus by changing the liquid volume in the lens. The lens shape calculated theoretically is a paraboloid. However, it is approximately a sphere near the central area. The deformation of the lens shape by gravity was also calculated with a simplified structure in which the lens was held vertically and found to be independent of the elastic properties of the film. The effect of gravity was found to be negligible when the pressure at the liquid pump was more than 30 times that induced in the liquid at the bottom of the lens by the gravity. The aberrations of the lens were calculated and observed to be negligibly small compared with the normal convex spherical single-glass lens. A liquid-filled lens was fabricated and experimentally evaluated.

Plasma polymerized methyl‐methacrylate as an electron‐beam resist

Plasma polymerized methyl‐methacrylate thin film was formed on a glass substrate coated with chromium as a resist for electron‐beam lithography. The polymerizations were conducted at two discharge frequencies of 13.56 MHz and 5 KHz using a capacitively coupled discharge electrode system in a bell‐jar‐type reactor. Delineations were carried out using an electron beam whose diameter and acceleration voltage were 0.5 μm and 20 kV, respectively. As a test pattern, 25 pairs of parallel lines and spaces each having a 10‐μm width were delineated in a rectangular area of 0.5×0.5 mm2. Each line of 10‐μm width was depicted by sweeping over using the electron beam with 20 repetitions. The patterns were developed on the chromium by CCl4 plasma etching.

Characterization of hard transparent B–C–N–H thin films formed by plasma chemical‐vapor deposition at room temperature

B–C–N–H thin films were deposited by plasma chemical‐vapor deposition with an external capacitively coupled reactor at an rf frequency of 13.56 MHz. The films were formed from a gas mixture of B2H6 (5.25 vol % in N2), methane, and argon or nitrogen as carrier gases. The deposition was carried out at room temperature and without heating the substrate. The films were transparent in the range of 10 000–2000‐A wavelengths. The Knoop microhardnesses were 1825–3324 kg/mm2 and the refractive index was 1.3–1.6. An extensive discussion of the effect of the deposition conditions on both microhardness and film composition is given. In addition, the interrelation between the microhardness and composition is illustrated.

Transparent BCNH thin films formed by plasma chemical vapour deposition

Abstract BCNH thin films transparent at wavelengths of 200–1000 nm were deposited by low temperature plasma chemical vapour deposition using an inductively coupled reactor at a frequency of 13.56 MHz. The films were formed at a discharge power level of 20 W and a pressure of 48.1 Pa from a gas mixture of diborane (4.8 vol.% in nitrogen), ethane and argon. The refractive index was 1.4 and the deposition rate was 20 nm min−1 when it was measured with an ellipsometer at a wavelenght of 632.8 nm.

Influence of oxygen on electrical properties of styrene thin film polymerized in a glow discharge

The conductivity and the capacitance of thin polystyrene films polymerized in the atmosphere of a glow discharge were measured in vacuum, argon, oxygen, and air. The conduction current did not change apparently with an introduction of argon, but decreased abruptly with an introduction of oxygen. Such a trend was also found on the capacitance. The concurrent changes in conductivity and capacitance may be due to a reaction of free radical with oxygen. These experimental results can be interpreted as a disappearance of space charge on exposure to oxygen.

2–10 nm scale plasma polymerized organic films

Ultrathin organic films can be used in electronics for several applications. There are a few ways of preparation of such films and one is plasma polymerization. Traditionally, comparatively thick films, 100–1000 nm, are deposited by this method and studied. But, for electronic devices, 10 nm or thinner films are of great importance to any wet technique considered to be unsuitable for perfect layer formation. In this work we have deposited 2–10 nm scale ultrathin hydrocarbon films on silicon wafers. A capacitively coupled rf discharge was initiated in a short residence time box‐type reactor in a uniform flow of an acetylene/argon mixture. The gas kinetic residence time in the plasma zone was limited to 5–70 ms to decrease synthesis of heavy gas phase products and to suppress particulate formation. Distribution of film thickness after the deposition was measured by an ellipsometer. The film surface topography was studied by an atomic force microscope that shows the films are smooth and pinhole free. Thus ou...

Applications of plasma polymerization

Plasma etching of polymeric material and plasma polymerization of monomers were performed by using two types of reactors, which are a tubular type and a gas flow type reactor. Phenomena of deposition and ablation of organic materials in low temperature plasma are discussed in relation to the practical processes. INTRODUCTION Plasma chemical processes of organic material in low temperature plasma are given attention in various fields of technical development. The principal processes are organic thin film coating, surface modification and etching of polymeric substrate. The processes are performed under irradiation of electrons, ions, protons and activated neutral particles in a wide range of energy level. Therefore, the phenomena in the processes are usually complicated and the process is difficult to be regulated. However, several kinds of applications were attained because of technical developments of evacuation systems, discharge power sources, diagnostics and surface analysis. In this study, several experiments on plasma etching of polymeric material and plasma polymerization were performed by using two types of reactors, which were a tubular type and a gas flow type. The interaction between plasma and polymeric materials in low temperature plasma will be discussed. Recent results of application will be also introduced. GENERAL FEATURES OF PLASMA CHEMICAL PROCESSES FOR ORGANIC MATERIALS Effect of Energetic Particles Irradiation On Vinyl Polymers It is well known that the plasma chemical process is affected by chemical propertst of polymeric materials under the plasma irradiation. Lawton et al.(ref. 1 and 2) classified conventional vinyl polymers into two groups as shown in Table 1: those that become degraded under high energy irradiation and those that become cross-linked. According to Miller et al., there is a simple correlation of radiation effect and chemical structure of vinyl polymers which have a following generalized structure(ref. 2).

Vacuum lithography—A completely dry lithography using plasma processing

The purpose of this paper is to describe a thoroughly dry lithography using plasma polymerization and plasma etching. The new lithography is named vacuum lithography because all processes are performed at reduced pressures. Resist films were formed in bell-jar-type and argon-flow-type reactors. The controllability of plasma polymerization is discussed with respect to the type of reactor and gas mixture. A pattern was delineated in the resist using an electron beam, and it was developed by plasma etching with a mixture of argon and oxygen. It was found that the quality of the plasma-polymerized resist depends strongly on the polymer structure and on the plasma etching conditions. In this experiment, the recorded values of sensitivity and γ value of plasma-polymerized methyl methacrylate were 700 µC/cm2 and 1, respectively.

Thin Polymer Films by the Glow-Discharge Indirect Method

Abstract The growing mechanism and the structure of thin polystyrene film by the glow discharge-indirect method are discussed. A theoretical relationship between the growth rate of polymerized film and the discharge condition is deduced on the basis of Polls model, taking the charge transport processes in the discharge space into consideration: 1) the ambipolar diffusion, 2) the recombination of charges forming the ion sheath, and 3) the effect of stray capacity. Substitution of possible values of physical parameters on the gaseous plasma into the theoretical relation give a reasonable growth rate which agrees well with the experimental results. From NMR, ESR, and dielectric experiments, it is suggested from the molecular and morphological structure of the film that small molecules and free radicals remain, but most of the film consists of a three-dimensional mesh structure.

Effect of Sn in plasma copolymerized methylmethacrylate and tetramethyltin resist on plasma development for x‐ray irradiation

Plasma copolymerized methylmethacrylate and tetramethyltin [PP(MMA–TMT)] was prepared using an inductively coupled gas flow‐type reactor. The atomic ratio of tin to carbon (Sn : C) in PP(MMA–TMT) was varied from 0 to 0.15 by changing the gas flow rate ratio of both TMT and MMA monomers. The characteristic of PP(MMA–TMT) as a resist was evaluated in dry lithography processes, in which the resist was exposed to radiation of CuKα (main wavelength: 1.54 A) and x‐ray imaged pattern in the resist was developed by Ar–20% O2 mixture gas plasma using a parallel plate electrode‐type reactor. The sensitivity of positive resist was defined by the minimum dose rate that the resist in the exposed part was etched off when the remaining thickness at the unexposed part became about 38% of the initial film thickness under the plasma development. PP(MMA–TMT) resist showed the highest sensitivity of 8 J/cm2 at Sn : C of 0.046. The molecular structure of PP(MMA–TMT) film was investigated by electron spectroscopy for chemical ...