Madoka Nishiyama

Super-High-Density Optical Disk Using Deep Groove Method.

An optical disk with a deeper-than-usual groove has been manufactured. The deeper the groove, the less cross-erase occurs. By adjusting the groove depth, cross-erase is suppressed even if the track pitch is narrowed to 0.5 µm. Also, we found another groove depth which cancels both cross-talk and cross-erase. Finally, we obtained a high-density optical disk with a deep groove, the track pitch and the minimum mark length of which are 0.5 µm and 0.35 µm, respectively.

Micro-mirror On Ribbon-actuator (MOR) for high speed spatial light modulator

To realize a high throughput optical mask-less lithography (OML) which is utilized for the semiconductor integrated circuit (IC) mass fabrication, we have been studying the high speed spatial light modulator (SLM). In this paper, we report a Micro-mirror On Ribbon-actuator (MOR) as a novel MEMS SLM. The MOR consists of a ribbon actuator which carries a mirror placed on the offset position. The mirror tilts when the ribbon actuator is bent by electrostatic force. The high speed driving of the MOR is realized by the high resonant frequency of the ribbon actuator and the large damping factor of the submicron gap. The MOR showed the routinely switching response of less than 3 musec and the resonant frequency of around 1.7 MHz. The 8times8 passive matrix drive of the MOR was also demonstrated.

Built-In Upwards-Bending Electrostatic Actuator Capable of Three-Level-Structural Variable Capacitor

We have developed a new electrostatic actuator consisting of multilevel structure, which can move in a long distance with no need of a high driving voltage. This actuator features to have a built-in upward-deflection. We have also developed a variable capacitor, which can be controlled with a capacitance ratio (C/R) higher than 10 using a new configuration of the actuators and capacitor plates. The overall process to make these devices is quite easy to integrate with the CMOS circuits.

Deep groove method on high density optical disk memory

Recently, standardization of the DVD-RAM and that of the 8/spl times/130 mm MO are about to be finalized. These standardizations are expected to accelerate the use of optical disks in the area of multi-media. To achieve higher density optical disks, it is necessary to narrow the track pitch without working at shorter wavelengths. This paper describes an optical disk in which data is recorded on both lands and grooves with a reduced track pitch and a deeper-than-usual groove, a technique we call the deep groove (DG) method.

Extremely High Capacitance Ratio (C/R) RF MEMS Variable Capacitor with Chameleon Actuators

In this paper, we propose a novel variable capacitor having higher capacitance ratio (C/R) >35 than ever before. So far, various types of RF-MEMS variable capacitors have been proposed, but even the highest C/R among the capacitors under development is now the order of 4. For enabling the multi-band of the wireless terminal, it has been expected to achieve a device having higher C/R. We demonstrate by combining arbitrarily the quantity of the chameleon actuators and the area of capacitor plate, the capacitance value can be digitally controlled in a wide range.

Diffractive White-Light Diffuser with Subwavelength Structure

Diffractive diffusers have some desirable characteristics, whereas they have a large dependence on wavelengths. For their application over a wide wavelength range, achromatization is planned for diffractive-type optical diffusers. A diffracted pattern can be achromatized by fixing the ratio of each optical path area and optimizing the multiwavelength diffracted patterns simultaneously. Subwavelength pillar structures are used for multilevel optical path regions. We fabricated test pieces to demonstrate this method. Patterns were formed by KrF and ArF stepper lithography and dry etching, and then replicated to resin by UV nanoimprint. Simulations and measurements gave similar results, which suggests that these methods for achromatization work well. Diffractive white-light diffusers will be realized when elements with subwavelength high-aspect-ratio pillar structures are fabricated precisely as designed.

High quality optical disc stampers with round edge grooves

We describe a deep groove having round edges in the optical disc substrate as one of solutions for difficulty in injection molding. The round edge deeper grooves were actually made and tested. Stampers with the round edge grooves can be easily made by modified directly engraved glass mastering. Replication separability from the stamper is markedly improved. No cloud problem, shorter cycle time at replication process and longer lifetime of stampers were confirmed.