Electron Density and Electron Temperature Control with a Magnetic Field and a Grid in Inductively Coupled Argon Plasma

The mechanism of electron density and temperature being influenced by a magnetic field and a grid is studied through inductively coupled Ar plasma discharge simulations and experiments. The electron density, electron temperature, ion density, plasma potential and electron energy distribution function are measured by an Impendans Langmuir probe. The conditions for all experiments are an argon gas pressure of 0.5 Pa and an RF power supply of 3.0 kW to discharge. Simulations and experiments reveal that the magnetic field constrains the mass of electrons, thus reducing the mean-free path and increasing the chance of collisions with gas. Therefore, the ionization rate will increase in the source region, which causes a low electron temperature. Coupled with plasma expansion, the magnetic field could cool the electron temperature and reduce the electron density in the diffusion region. When applying a magnetic field to the plasma, the electron density is controlled from 9.50 × 1010 to 7.30 × 1010 cm−3, while the electron temperature decreases from 4.04 to 3.80 eV. For the grid (ground bias) influence, the electron density sharply decreases to 1.98 × 1010 cm−3, and the electron temperature decreases to 3.30 eV. A mass of electrons is absorbed by the grid. Changes in other plasma parameters, such as the plasma potential and ion density, are also shown in the results. Compared with the magnetic field effect, the influence of the ground bias grid is more obvious.