The Influence of Antenna Configuration and Standing Wave Effects on Density Profile in a Large Area Inductive Plasma Source

A large area inductive plasma source driven by a 13.56 MHz traveling wave has been investigated. Launching a traveling wave by a tuning network eliminates standing wave effects to obtain a uniformly excited processing plasma. The designed tuning network is capable of launching a wave with any standing wave ratio. The influence of standing wave effects on plasma density profile is thus studied under various operating conditions. The influence of antenna configuration on the density distribution is examined by varying the number of powered rods and the way in which the exciting wave is launched. The plasma properties, such as ion density profile, electron temperature, and plasma potential are measured using a Langmuir probe and a capacitive probe. Our experimental results show that both the antenna configuration and voltage standing wave ratio are crucial in controlling the plasma density profile. A comparison of experimental results with theoretical analysis is performed.