A microwave-induced unmagnetized plasma source for plasma processing

A simple microwave-induced large-diameter unmagnetized plasma at low pressure with an Okamoto cavity for plasma processing is presented. A quartz discharge tube (6.4 cm in diameter and 10 cm long) is placed inside the cavity. An argon plasma is produced in the discharge tube and effuses into a process chamber (stainless steel, 14 cm in diameter and 24 cm long). The electron density, electron temperature, ion current density and floating potential in the chamber were measured as a function of spatial position using a Langmuir probe. An electron density over , with an electron temperature in the 3 eV range, was obtained at pressures in the mTorr range with 2.45 GHz 500 W input microwave power.