Impedance of RF Capacitive Coupled Plasma: A Simulation and Analytical Study

The formation of RF capacitive coupled plasma(CCP) of helium was empirically approximated by ignoring the convection of heavy particles,mathematically formulated with 1 D plate-plate electrode model,theoretically analyzed and numerically simulated in finite element method.The influence of the four key variables,including the pressure,input power,electrode-diameter and gap-length,on the CCP-impedance was investigated in simulation and by data analysis.The simulated results show that the key variables all have a major impact.To be specific,as the pressure and gap-length increase,the CCP-impedance changes in a decrease-increase(V-shape) mode,simply because the probability of collision ionization varies in an increase-decrease manner;as the electrode diameter and input power increase,the CCP-impedance decreases,slowly approaching a stable value.We suggest that the simulated results be of some basic and technological interest in industrial plasma engineering.