Spatial distribution and transport mechanism of electrons in large and powerful inductively coupled plasma sources with Faraday shield

Abstract

A large and powerful radio frequency (RF) inductively coupled plasma (ICP) source with a Faraday shield (FS) has been investigated by a 3D fluid model, consisting of a plasma module and an electromagnetic field module. Effects of the structure of the FS, the RF current, and the gas pressure on the spatial distributions of plasma parameters including the electron density, electron temperature, and electron potential barrier are investigated systematically. The results show that the FS has a great influence on the spatial distribution and transport mechanism of electrons. The electron density has a maximum value at the center of the ICP source and declines sharply near the FS. Furthermore, it decreases obviously with the decreasing slit width, due to the electron transport mechanism, which is directly related to the electron potential barrier and electron temperature. In addition, the electron density increases with the RF current and gas pressure; it is noteworthy that the stronger induced electric field heating exists at the slit gap under high RF current that makes the electron temperature increase. The data obtained in this paper could lead to a deeper insight into the characteristics of ICP sources, which is extremely essential for optimizing the FS structure and designing large and powerful radio frequency ICPs in the future.