Planar microwave discharges with active control of plasma uniformity

Abstract

Planar microwave discharges using a multi-slotted planar antenna are investigated. The enhancement of the microwave fields near the plasma resonance is observed in accordance with the theory of the resonant absorption. By operating the antenna with the azimuthally rotating fields, highly uniform overdense plasmas can be produced without being affected by eigenmode structures of surface waves. As a result, the radial distribution of the ion saturation current can be controlled by tailoring the power radiation profile from the antenna. It is also demonstrated that the active control of the plasma uniformity is possible by simply changing the vertical position of the antenna.