Measurement of Spatial Distribution of SiF₄ and SiF₂ Densities in High Density SiF₄ Plasma Using Single-Path Infrared Diode Laser Absorption Spectroscopy and Laser-Induced Fluorescence Technique

The measurement method for determining absolute densities of SiF 4 molecules in a reactive plasma has been established using infrared diode laser absorption spectroscopy (IRLAS). The spatial distribution of line averaged absolute densities of SiF 4 molecules has been investigated in the electron cyclotron resonance (ECR) plasma reactor employing SiF 4 gas using infrared diode laser absorption spectroscopy without a multiple reflection cell, namely, single-path IRLAS. Furthermore, the spatial distributions of SiF 2 radical densities are measured using laser-induced fluorescence (LIF) technique. It was found that the line averaged absolute density of SiF 4 molecules indicated the hollow-type distribution in the reactor, while SiF 2 radical densities had the maximum value near the plasma boundary. On the basis of these measured results, the formation mechanism of spatial distribution of SiF 4 and SiF 2 densities in the plasma reactor are clarified.