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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 SiF4 molecules in a reactive plasma has been established using infrared diode laser absorption spectroscopy (IRLAS). The spatial distribution of line averaged absolute densities of SiF4 molecules has been investigated in the electron cyclotron resonance (ECR) plasma reactor employing SiF4 gas using infrared diode laser absorption spectroscopy without a multiple reflection cell, namely, single-path IRLAS. Furthermore, the spatial distributions of SiF2 radical densities are measured using laser-induced fluorescence (LIF) technique. It was found that the line averaged absolute density of SiF4 molecules indicated the hollow-type distribution in the reactor, while SiF2 radical densities had the maximum value near the plasma boundary. On the basis of these measured results, the formation mechanism of spatial distribution of SiF4 and SiF2 densities in the plasma reactor are clarified.