Stable Surface-Wave Plasma through Excitation of Standing Surface Wave Using Plane Multislot Antenna

Abstract

A stable high-density and low-temperature plasma was realized through excitation of standing surface waves using a plane multislot antenna. On a dielectric-window surface, the surface wave introduced from a slot interferes with that from the adjacent slot to generate a standing surface wave with odd loops at an interval of one-half wavelength of the surface wave between the slots. The plasma density is 2-10×1012 cm-3, thus the skin depth is 1.5–4 mm in the wide pressure range from 10 mTorr to 1 Torr. A superior high-density plasma with a relatively high temperature is generated near the dielectric window and a high-density plasma bulk with a low temperature is sustained through the intrinsic diffusion and the relaxation of the generated plasma. At high pressures of about 1 Torr, the plasma itself is confined near the dielectric window. The plasma is suitable for various applications, especially for high-rate and low-damage processes using large-area substrates.