The effects of Complex Eigen modes and frequencies in a Finite-Area Plane Surface Wave Plasma

As a semiconductor manufacturing plasma source, surface wave plasma (SWP) which generates a specific wave mode between the plasma and a dielectric plate is widely used. To improve power transfer efficiency for plasma generation, it is necessary to optimize resonant frequency at dielectric surface. For this purpose, a cylindrical microwave source which uses surface wave excitation has been developed. A higher-order mode cylindrical cavity resonator is used for plasma generation. Electromagnetic waves generated by solid-state power amplifier system, which can be controlled at an operating frequency of 2.4 to 2.5 GHz, are propagated to the cylindrical resonator. Based on the electric field distribution of the cylindrical cavity, electromagnetic waves propagate through a hybrid type slot antenna composed of large aperture structures. The electric field distribution of the surface wave (TM mode) formed on the dielectric window surface varies with operating frequency control and plasma characteristics (electron density, momentum transfer frequency). This effect is experimentally and numerically confirmed in Ar and Ar/O₂ plasma at 0.1~1Torr with total injection powers from 0.6 to 1.5 kW, which shows surface wave mode is affected by complex eigen modes and frequencies.