Plasma chemistry and diagnostic in an ArN2H2 microwave expanding plasma used for nitriding treatments

International audienceThis paper reports on mass spectrometry analysis performed downstream a microwave discharge in Ar-N 2 -H 2 gas mixture in nitriding conditions. Investigations are focused on the main simple radicals NH 2, NH and N, and on the molecular species NH 3 and N 2 H 2 produced. Because of wall desorptions due to catalytic effects, we must develop a specific method taking into account both wall desorption and dissociative ionization effects, in order to correct the mass spectrometer signal intensity. The relative concentrations of the previous species are studied in various gas mixtures. Correlations are made between the plasma chemistry and plasma parameters (electron density and energy electron distribution function), measured by means of Langmuir probes spatially resolved within the plasma expansion. These results show the efficiency of ternary gas mixtures (Ar-N 2 -H 2) to produce electrons and N x H y species used in plasma nitriding process