Plasma Generation with a Resonant Planar Antenna

摘要

A planar RF antenna is presented for potential plasma processing applications. It consists of an arrangement of elementary resonant meshes which presents a set of resonant modes, i.e. resonant frequencies. When excited at one of these frequencies the antenna develops a strong sinusoidal current distribution. A rectangular RF (13.56 MHz) plasma source with a 0.2 m×0.55 m antenna has been built and electron densities of about 4.1011 cm~(-3) have been measured by 33 GHz interferometry at a distance of 4 cm from the source plane for an injected RF power of 2000 kW. The discharge was shown to be driven by inductive coupling with the resonant current distribution of the antenna. For an operating pressure of 5 Pa the plasma non-uniformity was less than ±5% over 75% of the antenna surface. Besides its high efficiency for plasma generation, this antenna has the key advantage of being theoretically scalable up to very large surfaces without presenting the usual limitations in terms of RF power injection and of impedance matching met by conventional large area plasma sources.