Control of power deposition profile for uniform plasma production in microwave and radio frequency ranges

Abstract
The spatial profile of power deposition to electrons is controlled in order to improve the uniformity of plasmas in electron cyclotron resonance (ECR) and radio frequency (RF) discharges. For ECR discharges use is made of a double-annular antenna which has a capability of adjusting the radiated power from two annular slits driven by two microwave sources. The radial profile of the ion saturation current can be varied from hill to hollow shape. Effects of this controllability on thin film deposition are also investigated. For RF discharges a lower hybrid wave in the RF range is employed to improve the uniformity of plasmas. In contrast to the helicon wave case, it is possible to change the radial region of wave propagation leading to a control of power deposition profile. The measured ion saturation current profile varies from hill to hollow shape in accordance with the theory.