Investigation of $H_2:CH_4$ Plasma Composition by Means of Spatially Resolved Optical Spectroscopy

The system based on spatially resolved optical emission spectroscopy dedicated for in situ diagnostics of plasma assisted CVD processes is presented in this paper. Measurement system coupled with chemical vapour deposition chamber by dedicated fiber-optic paths enables investigation of spatial distribution of species densities ($H_x$, $H^+$, CH, $CH^+$) during chemical vapour deposition process. Experiments were performed for a various gas inlet configuration at range of microwave power up to 800 W. Spatially resolved optical spectroscopy results showed that inlet configuration based on injecting hydrogen in ECR region and methane in substrate area is the most efficient for $H^+$ and $CH_{3}^{+}$ excitation. The designed prototype of the spatially resolved optical spectroscopy system enables the high-sensitivity measurements of concentration of the species in the microwave plasma and can be used for optimisation of diamond-like carbon synthesis.