Kiyoshi Seshimo

Effect of Groove Pattern of Chemical Mechanical Polishing Pad on Slurry Flow Behavior

In chemical mechanical polishing (CMP), the slurry flow behavior on the polishing pad is very important both for improving polishing effectiveness and for reducing the slurry consumption. In this study, we aim to evaluate two types of CMP pad that have unique special groove patterns, slurry outflow and inflow pads, for controlling the slurry flow behavior. We describe the effect of the groove patterns on the slurry flow behavior observed using images recorded using a high-speed digital camera. The results of the study indicate several advantages of the proposed pads over the conventional pads from the viewpoint of slurry flow behavior.

Development of innovative “dilatancy pad” realizing super high efficiency and high-grade polishing of SiC wide band Gap semiconductor substrates

In this study, we perform the collaborative research and development with various specialized companies such as machine/system, polishing pad and abrasive/slurry. We aim at the establishment of the high efficiency and high-grade polishing of hard-to-process semiconductor substrates in particular with SiC and GaN. We propose and devise an innovative polishing pad as a part of the fusion processing establishment. The unprecedented innovative special polishing pad (dilatancy pad) can realize removal rates more than 2.5 ~ 10 times in comparison with a conventional metal plate. And, the occurrence frequency of the processing damage (scratches, outbreak depth of polishing damaged layers) can be improved drastically in comparison with conventional method. In the middle polishing process, we have figured out to lighten the load from the final polishing by reducing generation of polishing damage using our new method instead of the conventional one. As a result, we have realized the super high efficiency and high-grade polishing of the hard-to-process semiconductor substrates.

Proposal and development of a novel high-speed/high-pressure polishing machine aiming at the super high efficiency process of the hard-to-process substrates

In recent years, wide band gap semiconductors, such as SiC and GaN, are attracting extensive attention as an alternative material of Si semiconductors. However, issues such as reduction of the production cost and improvement of the productivity prevent wide-spread application of these materials in the world. This study was conducted under the collaborative research and development with various specialized companies such as machine/system, polishing pad and abrasive/ slurry. We aim at the establishment of high efficiency and high-grade processing of the wide gap semiconductor substrate. We introduce an outline of the high-speed / high-pressure polishing machine, which remarkably outperforms the conventional polishing equipment (Wafer pressure: 1,000 MPa (Max), platen/ wafer rotation speed; 1000 min-1 (Max)). This machine enabled the high efficiency polishing of the hard-to-process substrates by adopting a high-performance / high power motor and rigid frame structure. Moreover, to solve the problems of slurry scattering at high-speed operation and resulting pad heating under the high pressure condition, we have developed a slurry self-returning system. This novel machine tremendously improve the productivity of the high efficiency wide gap semiconductor devices in terms of production efficiency, reduction of processing time and cost through fusion of each elemental technology such as polishing pad, abrasive/slurry, the developed machine/system, and optimization of process condition.

Development of novel groove patterns for CMP pad

This study aims to develop the CMP pads that have new groove pattern as control the slurry flow. We have been proposed two type groove patterns as inflow type and outflow type. Here, it is well known that the slurry flow is remarkably important as both to use the slurry effectively and to reduction the slurry quantity consumed of CeO2 abrasive that is one of rare metals. This paper describes the effect of groove pattern on the slurry flow from the observation image with high-speed camera. In particular, the slurry flow is quantitatively visualized by digital image processing. As a result, the several advantages of both proposed inflow type and outflow type show from a view point of slurry flow compared to the conventional XY-groove pad and No-groove pad.