Abstract
A large-area high-density microwave plasma is successfully generated at low pressure by a tunable surface wave cavity which consists of a 12 period vane-type slow wave structure. This cavity is operated in the π mode and resonant at 2.45 GHz. The plasma area is in excess of 50 cm×25 cm with a uniformity of ± 10% at pressures less than 30 mTorr. A plasma surface wave has been excited so that a plasma density as high as 1.0× 10 12 cm -3 can be achieved at 30 mTorr for a microwave power of 2.0 kW. The plasma temperature is ≃1.5 eV and the plasma potential is ≃12 V. Above all, the number of the periods of the π-mode cavity can be increased without changing the resonance frequency and the distribution of the microwave fields such that this plasma source is easy to up-scaled. © 1999 American Institute of Physics.