Magnetic control of nonlinear electron resonance heating in a capacitively coupled radio frequency discharge

Abstract

In magnetized capacitively coupled radio frequency (RF) plasmas operated at low pressure, the magnetic asymmetry effect (MAE) provides the opportunity to control the discharge symmetry, the DC self-bias, and the ion energy distribution functions at boundary surfaces by adjusting a magnetic field, that is oriented parallel to the electrodes, at one electrode, while leaving it constant at the opposite electrode. This effect is caused by the presence of different plasma densities in regions of different magnetic field strength. Here, based on a balanced magnetron magnetic field configuration at the powered electrode, we demonstrate that the magnetic control of the plasma symmetry allows to tailor the generation of high frequency oscillations in the discharge current induced by the self-excitation of the plasma series resonance (PSR) through adjusting the magnetic field adjacent to the powered electrode. Experimental current measurements performed in an argon discharge at 1 Pa as well as results of an equivalent circuit model show that nonlinear electron resonance heating can be switched on and off in this way. Moreover, the self-excitation of the PSR can be shifted in time (within the RF period) and in space (from one electrode to the other) by controlling the discharge symmetry via adjusting the magnetic field.