CF and CF2 Radical Densities in 13.56-MHz CHF3/Ar Inductively Coupled Plasma

Abstract

Radial and axial distributions of CF and CF2 radical densities in CHF3/Ar inductively coupled plasma (ICP) generated by a radio frequency of 13.56 MHz were evaluated using laser-induced fluorescence (LIF). The radical densities in the bulk plasma were estimated by combining the density distributions measured by LIF with the absolute radical density measured by appearance mass spectrometry (AMS) near the reactor wall. Axial and radial distributions of CF and CF2 radical densities were extremely hollow. The radial distribution was strongly correlated with the electron density distribution and was significantly influenced by the dissociation process resulting from the electron excitation in the reactor space. The axial distribution, on the other hand, was mainly determined by the surface reaction of radicals on the wafer.