Computational Characterization of a New Inductively Coupled Plasma Source for Application to Narrow Gap Plasma Processes

Since the recent advent of serious problems in the plasma fabrication processes (bowing, faceting, notching, and twisting) is related to the polymer control issue. The polymer control on the wafer surface by controlling the radical composition in the plasma has become a major mission in the fabrication industry. This polymer control has been successfully performed in the capacitively coupled plasma (CCP) source. The CCP source can be operated in the small volume condition (narrow gap) without the loss of good uniformity of plasma. Unlike the CCP source, the inductively coupled plasma (ICP) source needs large enough space to make a uniform plasma via the plasma diffusion process. The polyer control in the ICP source has been very difficult for an increased residence time of radicals due to large space. To reduce this problem, we propose a new ICP antenna named quadrupole antenna. It can make a uniform plasma in a narrow gap, compared with the conventional ICP antenna. A comparative electromagnetic simulation study between the quadrupole and the conventional ICP antennas shows that the quadrupole antenna makes better symmetric and uniform RF fields close to the antenna compared with the conventional antenna. The key elements are the perfect symmetric structure and the restricted radiation property of the proposed quadrupole antenna.