Effect of electron kinetics on plasma density in inductively coupled plasmas using a passive resonant antenna

Abstract

We investigated the profiles of electron and ion densities dependence on the gas pressure in the inductively coupled plasma with a passive resonant antenna. The inner powered antenna and the passive resonant antenna are independently installed on the top of the chamber, and a power of 13.56 MHz is applied to the powered antenna. A significant change in the plasma density profile is observed when the capacitance of the passive resonant antenna is adjusted from non-resonance to resonance. At a high pressure of 50 mTorr, the point of maximum electron density and temperature shift from near the powered antenna to near the passive resonant antenna. However, at a low pressure of 1 mTorr, the profile of the electron density and temperature hardly change, and the maximum electron density at resonance increases about 1.4 times (at 150 W) to 4 times (at 50 W) higher than at non-resonance. The controllability of the electron density profile, which depends on the gas pressure, can be understood by the electron kinetics effect, and the increase in the electron density can be explained by the increase in power transfer efficiency calculated from the circuit model. The electron density profile at bulk is compared to the ion density distribution at the wafer-level, and the results are discussed with the relevant physical mechanisms.