Improving the uniformity of RF-plasma density by a humped variable-gap spiral antenna

This paper develops a humped spiral antenna of top inductivelycoupled plasma with variable gap. Comparing with planar spiralantennae, it investigates the performance of humped spiral antennaein the calculated electromagnetic configurations and experimentalresults. It finds that the humped antenna has the improveduniformity of plasma density in the radial direction and thedecreased electron temperature in the top inductively coupledplasma. By experimental and theoretical analyses, the plasmaperformance in the case of humped antennae is considered to be thecombined results of the uniform electromagnetic configurations andthe depressed capacitively coupling effect.