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Effects of combined coils on the uniformity of RF ion source

The radio frequency (RF) ion source is significant in the industry because of its advantages of easy control and maintenance, low gas consumption, high energy and high-density plasma generation abilities. Unfortunately, the problem of high-density plasma uniformity limits its applications. RF coils, as the most important part of the ion source, play a critical role on plasma density and distribution. In this paper, we performed simulations of the combined coils magnetic field and plasma with power distribution and conducted process experiments with the RF ion source to obtain its etching uniformity by the characterization of a step profiler. The results show that the application of the same direction and a suitable coil current is beneficial to extend the uniformity range. The uniformity is improved by applying reversed coil currents. The results of process experiments are consistent with the simulation conclusions. This paper provides informative suggestions for the optimization of coil structures in the RF ion source.