Teruo Miyamoto

Free‐volume model for ionic conductivity in polymers

Electrical conduction in polymers under a relatively low applied electric field is considered to be ionic and is affected strongly by the structural factors of the polymers. The following equation for the electrical conductivity σ was derived in which free volume Vf, jump energy Ej, and ionic dissociation energy W were taken into consideration: σ=σ0exp{− [γ Vi*/Vf+(Ej+W/2e)(kT)−1]}, where σo is a constant, γ the numerical factor to correct the overlap of free volume, Vi* the critical volume required for transport of an ion, e the dielectric constant, k Boltzmanns constant, and T the absolute temperature. This equation describes well the conduction phenomena in polymethylmethacrylate, polystyrene, and an unsaturated polyester. Relationships between electrical conduction and free volume are discussed.

Suppression of static electrification of insulating oil for large power transformers

Streaming electrification in transformers occurs at the interface between the insulating oil and the insulating material as the oil circulates in the transformer. As a result, the insulating oil and the surface of the solid materials become charged and dielectric breakdown is possible within the oil or at the interface of insulating materials.

Photolithography system using annular illumination

Photolithography is a leading technique in LSI device fabrication. The LSI pattern size has approached the exposure wavelength such as the g or i-line of a Hg lamp. This fact indicates that the shorter wavelength or some novel technique will be needed in order to cope with finer patterns. It is known that annular illumination can improve the depth of focus and resolution. We applied the annular illumination method to the step and repeat exposure system. Experiments and simulations using annular illumination were carried out and subhalf-micron patterns were produced. The process latitudes of the annular illumination method are evaluated.

Proposals for an improvement in transformer diagnosis using dissolved gas analysis (DGA)

The diagnosis of oil-immersed transformers using the dissolved gas analysis (DGA) technique has been well accepted and widely used. IEC Publication 599 touches on the diagnosis of faults involving paper insulation based on the ratio of CO/sub 2//CO. It states that a fault involving paper insulation is probable when the CO/sub 2//CO ratio is 3 or lower; we would like to propose a figure of 10.

Absorption of CO/sub 2/ and CO gases and furfural in insulating oil into paper insulation in oil-immersed transformers

This paper relates to diagnostic methods for oil-immersed transformers. Diagnosis of internal condition of oil-immersed transformers using dissolved gas analysis technique is widely performed to monitor abnormalities in transformers or to estimate life expectancy of transformers. Carbon dioxide and carbon monoxide gases have been found to be good indicators of transformer condition. Furfural has drawn attention of experts as another good indicator since a few years ago. It is commonly observed that concentration of CO/sub 2/ and CO gases in insulating oil in transformers fluctuates appreciably depending on time of sampling. The authors examine the possible causes of the fluctuation and come to the conclusion that temperature dependence of absorption of those gases into paper insulation in transformers is the main cause of the fluctuation. This paper describes theoretical and experimental studies of the phenomenon in detail. It is shown that the accuracy of dissolved gas analysis can be greatly improved if the phenomenon is taken into account.<<ETX>>

Photolithography System Using Modified Illumination

Since the LSI pattern size has approached the exposure wavelength, various methods have been developed to overcome limitations in photolithography. This fact indicates that a shorter wavelength or some novel techniques will be needed in order to cope with finer patterns. The modified illumination method was proposed in order to improve the depth of focus and resolution limit. We applied the modified illumination method to the step-and-repeat exposure system. Experiments using modified illumination were carried out and sub-half-micron patterns were produced. The process latitudes of the modified illumination method are evaluated.

Photolithographic system using modified illumination

A modified annular illumination method known as PHOENEX (Photolithography enhanced by modified exposure) is discussed. Compared with annular illumination, the modified illumination effectively cuts off the background element, which does not contribute to the imaging. In this study, the process latitudes of the modified illumination are evaluated using experiments and simulations. The DOF limit is doubled compared to the conventional method. The optical contrast is improved by the shifter-shade-type phase shift mask. The resolution limit is also improved by the modified illumination.<<ETX>>

Photolithography system using a combination of modified illumination and phase shift mask

Various methods have been developed to overcome the limitations in photolithography. Modified illumination and phase shift mask technologies have been developed in order to improve the depth of focus and resolution limit. We have combined these two methods and applied them to the step and repeat exposure system. Experiments using the modified illumination were carried out and subhalf-micron patterns were produced. The process latitude of 64M dynamic random access memory (DRAM) is doubled by this combination process.

Proposal of a Next-Generation Super Resolution Technique

A super resolution technique has been developed in order to support next-generation devices. We found that the super resolution technique was effective for smaller patterns but not for larger ones, leading to the restriction of its applicability. In order to obtain wider applicability, we propose a new optical system which has been improved and is applicable to all kinds of mask patterns. According to the proposed optical system, the mask pattern produces a specific source shape preferable for the mask pattern itself. Then the mask pattern is illuminated by this self-optimized illumination source. Thus optimal improvements can be obtained under the same illumination conditions, even if conventional patterns and phase-shift patterns of spatial frequency modulation types and diffracted amplitude modulation types are on the same photomask. Consequently, the super resolution technique will be brought into full use by this optical system.

New type of LCD projector with separately processed low-frequency chrominance and wideband luminance signals

We have developed an LCD projector based on a new concept utilizing human vision characteristics. It is known that human vision has high spatial resolution for monochrome images and low spatial resolution for color images. The new projector generates a wide-band frequency luminance signal, and low-frequency color signals from input signals. The present system uses an LCD panel of high definition for high resolution luminance image and three panels of low definition for low resolution color image. Use of low definition LCD panels, which are available at low cost, permits reduction in the cost of the system. In the developed projector, all the LCD panels have 640 X 480 pixels, but the number of pixels is electrically limited to 320 X 480 for the color panel. Light from a lamp is split by a polarizing beam splitter into two linearly polarized beams, one of which irradiates the luminance panel and the other of which irradiates the color panels, and thus both the polarized beams are utilized unlike conventional projectors where only one polarized component is utilized and the other component is lost away as heat. The projected NTSC (National Television System Committee) images were substantially of the same quality as the images which are obtained using three panels of 640 X 480 pixels. The projected VGA images had a picture quality sufficient for presentations at conferences.