Electron series resonance excited in the 27.12 MHz magnetron sputtering discharge

Abstract Electron series resonance (ESR) excited in a 27.12 MHz magnetron sputtering discharge was investigated. By analyzing the discharge impedances, the imaginary part of the impedance was found to undergo a transition from capacitive to inductive at varying radio-frequency (RF) power, and the conditions for ESR excitation were satisfied at 27.12 MHz magnetron sputtering. By analyzing the discharge current and its higher-order harmonics, the near-sinusoidal current waveform and weak second-order harmonic were obtained, showing a weak nonlinear effect of the RF current. However, for the magnetron sputtering discharge, the nonuniform magnetic field has a significant effect on the sheath width and transverse current, making the sheath thinner and the transverse current smaller. As a result, a small capacitive reactance was obtained, and the inductive reactance was easily canceled. Therefore, the ESR excited in the 27.12 MHz magnetron sputtering was caused by the strong effect of the nonuniform magnetic field and the weak second-order current harmonic (H2). By estimating the ESR frequency ω res, B , the second-order current harmonic (54.24 Hz) was found to be responsible for ESR excitation.