PAL SNU||2008||||Japan-Korea Symposium on Carbon Nanotube||||||Sung-Ryul Huh, Jung-Hyun Cho, Sun-Taek Lim and Gon-Ho Kim||Korea||In the synthesis of carbon nanotubes (CNTs), plasma enhanced chemical vapor deposition method (PECVD) is favorable because of its low temperature and vertical alignment process. The plasma plays an important role in producing the plenty of radicals so that the process can be done at the low temperature with a high growth rate. However, the energetic ions impinging on the CNTs cause a serious bombardment problem to limit the growth rate in the PECVD. If the plasma properties are controlled with the understanding of the CNT deformations irradiated by energetic plasma ions, it can be achieved the optimum condition for synthesis of MWNTs with the desired characteristics. In this study, the plasma properties were controlled by the inserted grid located on the substrate. Even this technique has been applied in many relevant processes for synthesis of MWNTs, the role of grid has not been investigated in details so that the improvement of process are still an open question. Our results revealed that the energy of incident plasma ions on the substrate becomes decreased with insertion of gird in the region of PECVD process. It could be achieved because the grid changes the space potential in the low density plasma and the impinging ions gain their energy lower compared to the case of no gird system. Also the grid reduces the plasma density locally, resulting in decrease the dose of incident ions. Thus the energy and dose of incident ions may be reduced by the inserted grid on the substrate. However, the radical has no effect from the existence of grid. In this study, the grid potential is manipulated to investigate the role of plasma and finally to achieve the optimum condition for MWNT synthesis. Synthesis of MWNTs was accomplished in H2/ CH4 microwave plasma source and temperature of Ni/Ti catalyst substrate was fixed at 650°C. Grid potential also was varied to control the energy of incident ions. Plasma parameters, especially, the ion density, temperature, and plasma potential in PECVD were measured by Langmuir probe (LP) and optical emission spectroscopy (OES). Also the synthetic characteristics of MWNTs were evaluated with plasma conditions. Results revealed, as been expected, that the grid may control the space potential as well as the ion density effectively so that the ion induced damages on CNT can be reduced and the growth length of MWNTs are improved with applied grid potential. Furthermore, the grid-inserted plasma has a lower electron temperature than that of plasma without the grid. It may affect local dissociation process. More details including recent results will be presented.