Masanori Hayase

Copper Bottom-up Deposition by Breakdown of PEG-Cl Inhibition

Copper bottom-up deposition in 200 nm trenches by an acid-copper sulfate with only two additives [poly(ethylene glycol) (PEG) and Cl ] is achieved. The inhibiting effect of electrodeposition by PEG is strongly related to Cl - concentration. Secondary-ion mass spectroscopy measurements show that Cl - is consumed in the electroplating process. The explanation of bottom-up deposition realized in copper superfilling, in which the decrease of Cl - concentration causes rapid electrodeposition on trench bottoms, is verified experimentally.

Miniature 250 μm Thick Fuel Cell with Monolithically Fabricated Silicon Electrodes

A fabrication technique of miniature fuel cell electrodes was developed from Si wafers. The fuel channels, porous layer, and catalyst layer were formed in the Si wafer. The fuel channels were fabricated by photolithographic patterning and subsequent wet etching on the Si. The porous layer was formed by anodization of Si from the polymer electrolyte membrane side through the bottom of the fuel channels. Catalyst metals were deposited inside the porous layer by wet plating. The two electrodes were hot-pressed with a Nafion 112 sheet. Open-circuit voltage of 840 mV and maximum power density of 1.5 mW/cm 2 were observed by hydrogen feed.

Preferential Copper Electrodeposition at Submicrometer Trenches by Consumption of Halide Ion

Preferential copper electrodeposition at submicrometer trenches in an acid copper sulfate electroplating bath by addition of only two components [bromide ion and polyethylene glycol (PEG)] is observed. Strong suppression by PEG is observed by the addition of Br - compared with the addition of Cl - . It is supposed that halide ions work as an adhesive between PEG and the copper surface. During electroplating, halide ions are consumed and the concentration of halide ions in submicrometer trenches is reduced by diffusional limitation. The reduction of halide ion concentration weakens the PEG adsorption and thus preferential copper electrodeposition at submicrometer trenches is realized. Nonuniform deposition observed by filling experiments is explained by this model.

Micromachined display device using sheet waveguide and multicantilevers driven by electrostatic force

A new structure for display devices is proposed and fabricated by the microelectromechanical systems process. The device is based on physical contact and evanescent coupling between a sheet waveguide and electrostatically driven multicantilevers. When incident light is propagated into the waveguide and the cantilevers contact the waveguide by applying a dc voltage, the switched light is emitted from the side edges of the contacted multicantilevers, resulting in a display device. The device contributes to the expansion of the switching area, the removal of unnecessary scattered light, and high contrast due to the simple fabrication and structure with corner spacers for the optical separation between the cantilevers and the waveguide. Based on the experimental results with the device, a contrast of 0.9 is obtained at 170 V, and a stable drive is realized up to 1 kHz. Therefore, the device can be expected to be used for display devices by the fabrication of an array structure.

Electric field analysis in a dilute solution for the vibrating electrode technique

Abstract In analyses of the scanning vibrating electrode technique (SVET), the conductivity of the electrolyte solution near the specimen is usually assumed to be uniform over space and constant over time when calculating the current density. These assumptions may be inadequate in practice, and non-uniformity due to electrolysis should not be ignored. To overcome these limitations, ion transport is considered in a dilute solution. To describe the ion concentration and electric field change close to the specimen surface, a model is used that employs the Nernst–Planck equation and the electro-neutral condition. A finite difference method is used to solve the resulting time-dependent axisymmetric problem. The computational results show good agreement with the experimental data obtained by SVET. It is also found that the electric potential gradient reduces to one-tenth of the initial value and of the result predicted by the conventional model with uniform conductivity.

Electrostatically driven micro-optical switching device based on interference of light and evanescent coupling

Two types of electrostatically driven optical switching devices have been developed in this paper. An interferometric optical switching device realizes selective wavelength filtering by the interference of lightwaves between two half mirrors. Also, an evanescent coupling surface-output optical switching device realizes on-off switching by evanescent coupling and physical contact. Their basic characteristics are experimentally evaluated. By integrating these devices on a substrate, switching devices with wavelength filtering and on-off switching are proposed.

Electrostatically driven display device using evanescent coupling between sheet waveguide and multicantilevers

In this study, a new display device based on physical contact and evanescent coupling is developed. The device consists of a glass substrate as a waveguide and electrostatically-driven multi-cantilevers on a silicon substrate. The incident light guided into the waveguide is transferred into the cantilevers due to the physical contact and the evanescent coupling between the waveguide and the multi-cantilevers when a voltage is applied. By the contact, the switched light is emitted from the side-edge of the contacted multi-cantilevers. The widely emitted output-light is realized by the integration of the cantilevers and the simplified structure. Therefore, the device is expected as the display application. The device is fabricated using MEMS process and bonding process. From the experimental results, a contrast of 0.9 is obtained at 170V, and the stable drive is attained up to 1KhZ. As a result, the usefulness of the device structure is confirmed.

Tapping force measurement by using micromachined cantilevers and laser systems

Measurement of periodical contact force of the tapping stylus is very important for performance evaluation of soft material profilometry. So far, simulations are perfomred to estimate the force, and force calibration cantilevers are used to measure small contact force of AFMs. Since the tappign stylus uses larger tappign force compared to AFMs, micro cantilevers made of glass are developed for the force measuremetn of range from mN to μN.The levers are calibrated by using a standard cantilever made of silicon,which is fabricated by a micromachining process. A laser interferometre system is used for the calibration of glass cantilever spring constant. A laser Doppler vibrometer is used to measure the velocity of the cantilevers, and the force is estimated from the velocity signal by an integration.

A Study on Relation between Brightness Uniformity of LCD and Cell Gap Deviation

The purposes of this study are to understand the relation between brightness uniformity of LCDs and its cell gap deviation caused by flatness of their substrates and to propose a flatness criterion of substrates considering human sensibility to the uniformity. Examinations are performed using periodic linear deviations in brightness uniformity on LCD cell samples. Result of psychophysical test shows that human sensibility to the linear defects depends on a cross gradient for the brightness signal projection to a linear direction. Therefore linear defects in uniformity can be evaluated by the gradient value. To demonstrate correlation between the deviation to brightness uniformity of LCDs and the cell gap deviation caused by flatness deviations of their substrates, some cross sections on LCD cell samples are tested. Brightness deviations are measured by image processing technique and cell gap deviations are calculated from measured surface profiles of their front and rear substrates that were pieces of the cells. Strong similarity between both deviations is observed. From this result it becomes clear that periodic linear deviations to the brightness uniformity on LCDs can come from surface corrugation of substrates caused by glass surface or coated layers. Then flatness of substrates can be evaluated according to the human sensibility to the brightness uniformity of LCDs by using gradient value of surface profiles and allowable limits of substrate corrugation can be determined by this experimental process in the same cell production condition.

Proposal of interferometric display device driven by electrostatic force

A new display device based on a micro-Fizeau interferometer (IDD: Interferometric Display Device) is proposed and trially manufactured. The mirror is suspended by leaf-springs so that it may move vertically when driven by a dc voltage - electrostatic force. The optical path difference between the half mirror and the bottom substrate is adjusted by the voltage, resulting in the optical interference. Contrast in the IDD can be changed by the voltage, and color can be displayed in the case of white light source. A 300micrometer-square half mirror made of SiO2 and Si substrate electrode/mirror is used for the construction of the IDD. A 4 by 4 array of the IDD is fabricated by using a bonding technique. An interferometric pattern in observed at a driving voltage of 200V dc. The frequency response of the device is confirmed more than 100Hz. The display quality is not sufficient at present because of the deformation of the half-mirror, however, it has a potential for lower driving energy and higher intensity of the pixels.