Effects of magnetic field on the secondary electron asymmetry effect in capacitively coupled plasmas

Abstract

The secondary electron asymmetry effect (SEAE) provides the opportunity to generate the dc self-bias voltage and asymmetric plasma response, where secondary electron emission coefficients at both electrodes are unequal. In this work, we use one-dimensional implicit particle-in-cell/Monte Carlo collision simulation to investigate the effects of the homogeneous and inhomogeneous magnetic field on the SEAE. The magnetic field is applied parallel to electrodes, and the discharge is operated in a geometrically and electrically symmetric capacitively coupled argon plasma. By comparing the simulation results of the effects of the homogeneous and inhomogeneous magnetic field on the SEAE, the homogeneous magnetic field can increase the dc self-bias voltage to a certain extent and has little effect on the plasma density distribution. The inhomogeneous magnetic field is more advantageous in generating the dc self-bias but at the cost of uneven plasma density distribution. In addition, by comparing the results of inhomogeneous magnetic fields with opposite gradients, we found that the value of the self-bias voltage can be changed by adjusting the magnetic field gradient. Aside from that the roles of two electrodes can be easily reversed by changing the slopes of the magnetic field gradient. The results suggest that such a configuration could be desired in the microelectronics industry, since the controllable self-bias voltage is needed for deposition and etching processes.