Hirotami Nakano

Development of Single Step Grinding System for Large Scale ϕ300 Si Wafer: A Total Integrated Fixed-Abrasive Solution

This research has developed an integrated manufacturing system for ϕ300mm silicon wafer, using fixed abrasive instead of conventional free slurry, to provide a totally integrated solution for achieving the surface roughness Ra < 1nm (Ry < 5∼6 nm) and the global flatness < 0.2μm/ϕ300mm. In addition to the space saving, this integrated system also significantly reduces the total energy consumption by 70%, compared with the current process used for ϕ200mm Si wafer. Three core technologies: the hybrid process mechanics, the GMM (giant magnetostrictive material) actuated positioning/alignment device and the ecologically friendly coolant circulation system are described in this paper. The system performance and results are then presented and discussed.

Angstrom positioning system using a giant magnetostriction actuator for high power applications

In this paper, an angstrom order positioning system using a giant magnetostriction actuator is proposed and developed. This newly developed system can precisely control several /spl Aring/ positioning over several /spl mu/m stroke range for practical use. This system can also deliver high power output to move payload ranging from several gf to several tons. Moreover, this system has achieved state-of-the-art backlash free positioning by using the newly developed elastic displacement table and a newly developed giant magnetostriction actuator.

Analysis of the current distortion factor of a three-phase, three-wire system

In a balanced three-phase system, the three-phase current distortion factor of three-phase ac power sources has been expressed by applying the conventional single-phase current distortion factor, which is defined for a single-phase system. However, in an unbalanced three-phase system, it is difficult to express the three-phase current distortion factor for distorted three-phase ac currents by means of the conventional single-phase current distortion factor. For instance, the conventional current distortion factors for three-phase ac currents are usually different from each other in the unbalanced three-phase system. To solve the above problem, this paper proposes a novel definition of the three-phase current distortion factor. The proposed three-phase current distortion factor is quite effective for the unbalanced three-phase system as well as the balanced three-phase system.

Development of Atomic Level GMM Positioning/Alignment System for Driving a Gigantic Weight Spindle. Core Technology for Advanced .PHI.300mm Si Wafer Ultraprecision Machine Tool.

In order to achieve damage free surface of Si wafer by a single step grinding process, each cutting edge should be controlled below the critical depth of cut. Additionally, the achievable wafer flatness by infeed grinding significantly depends upon the alignment between the wafer and the wheel. As one of the core technologies of an integrated manufacturing system for ∅300mm silicon wafer, a GMM (giant magnetostrictive material) actuated positioning/alignment device has been designed and developed to control half a ton payload at A resolution over the several μm stroke range (about 5μm) and simultaneously to align the co-axis between the work and wheel at the resolution of 0.1″. This paper describes the design of the GMM actuator and elastically deformable mechanism for position/alignment, the control schemes and on-situ performance.

A deadbeat control method for a PWM converter applied to a superconducting magnet

Current-type pulse-width-modulated (PWM) converter is regarded as one of the candidates for the superconducting magnet power supplies in next generation tokamak devices. However, this type PWM converter has a problem of the transient oscillation of the reactor current and capacitor voltage in an AC-side harmonic filter, which occurs owing to the LC resonance of the filter when the reference of the DC output current is changed rapidly. In this paper, the new PWM control method based on the deadbeat control theory is proposed to suppress the transient oscillation. The converter employing this method can control the reactor current and capacitor voltage in one sampling period under ideal conditions. In addition, the effect of dead time on the control is discussed. The performance of the newly proposed method is demonstrated through numerical circuit simulation.