Yoji Matsukawa

Polishing Mechanism of Glass Substrates with its Processing Characteristics by Cerium Oxide and Manganese Oxide Slurries

With an aim to reduce the consumption of cerium oxide (CeO2) used in large quantity for the polishing of glass substrates applied for HDD and display, we have attempted to obtain the processing characteristics of glass substrates by CeO2 slurry. We also paid attention to manganese oxide abrasives to replace cerium oxide abrasives. As a result, we have found Mn2O3 abrasives potential to replace disappearing CeO2 for the polishing of glass substrates.

Basic Characteristics of a Simultaneous Double-Side CMP Machine, Housed in a Sealed, Pressure-Resistant Container

We designed and manufactured a prototype of a unique CMP machine, which can perform double-side CMP simultaneously in a sealed and pressure container as regarding effective action of the processing atmosphere around workpieces as important. Polishing experiments with single crystal silicon (Si) wafers (100) are performed by charging the container with various gases. As a result, the removal rates increased by up to 25% under high pressure oxygen gas atmosphere.

Investigation of Surface Excitation Effect for Ablation of 4H-SiC Substrate Using Double-Pulse Beam

The authors investigate a low-fluence laser processing system with a femtosecond double-pulse beam and surface excitation of a power semiconductor wafer. The double-pulse laser processing method enables a semiconductor surface to be processed at a lower fluence and prevents penetration damage of the processed surface. The first pulse of the double beam is considered to have a role in exciting the semiconductor surface to increase the efficiency of light energy absorption. In this report, to verify the feasibility of low-fluence processing, we measure the damage threshold in the low-fluence ablation process.We are developing time-resolved grazing-incidence small-angle scattering (GI-SAXS) system using a soft X-ray laser. As a first step, we carried out GI-SAXS measurements of optical grating and craters produced on gold surface by femtosecond laser ablation . We succeeded in observing the diffraction spots from the grating as expected, but the diffuse scattering from the craters was hidden in thermal noises of a soft X-ray charge-coupled device camera.