Control of spatial plasma density distribution using parallel capacitor in an inductively coupled plasma

In inductively coupled plasma, the effect of controlling the plasma density distribution was observed by using variable vacuum capacitors (VVC) in a parallel antenna composed of internal and external antennas. To generate parallel resonance between the parallel antenna and the VVC, the VVC is connected in parallel between the parallel antennas. By varying the value of parallel VVC, the parallel antenna current increased and the impedance matcher current decreased when parallel resonance occurred. This increases the power transfer efficiency and thus increases the plasma density. Further, the VVC is connected in series with the external antenna of the parallel antenna to control the impedance of the external antenna in a situation where parallel resonance is maintained. Therefore, while maintaining the parallel resonance, an increase in the current of the antenna and an increase in the plasma density near the external antenna were confirmed. This allows control of the plasma density near the external antenna by varying the value of the series VVC. As a result, the plasma density distribution can be controlled into convex and concave shapes by increasing the current flowing through the external antenna.