Global simulation of plasma series resonance effect in radio frequency capacitively coupled Ar/O2 plasma

Abstract

Radio frequency capacitively coupled plasmas (RF CCPs) play a pivotal role in various applications in etching and deposition processes on a microscopic scale in semiconductor manufacturing. In the discharge process, the plasma series resonance (PSR) effect is easily observed in electrically asymmetric and geometrically asymmetric discharges, which could largely influence the power absorption, ionization rate, etc. In this work, the PSR effect arising from geometrically and electrically asymmetric discharge in argon–oxygen mixture gas is mainly investigated by using a plasma equivalent circuit model coupled with a global model. At relatively low pressures, as Ar content (α) increases, the inductance of the bulk is weakened, which leads to a more obvious PSR phenomenon and a higher resonance frequency (ω psr). When the Ar content is fixed, varying the pressure and gap distance could also have different effects on the PSR effect. With the increase of the pressure, the PSR frequency shifts towards the higher order, but in the case of much higher pressure, the PSR oscillation would be strongly damped by frequent electron–neutral collisions. With the increase of the gap distance, the PSR frequency becomes lower. In addition, electrically asymmetric waveforms applied to a geometrically asymmetric chamber may weaken or enhance the asymmetry of the discharge and regulate the PSR effect. In this work, the Ar/O2 electronegative mixture gas is introduced in a capacitive discharge to study the PSR effect under geometric asymmetry effect and electrical asymmetry effect, which can provide necessary guidance in laboratory research and current applications.