Temporal changes in absolute atom densities in H2 and N2 mixture gas plasmas by surface modifications of reactor wall

Real time vacuum ultraviolet absorption spectroscopic (VUVAS) measurements revealed that temporal changes in absolute atom densities in H2 and N2 mixture gas (H2/N2) plasmas were affected by the conditions of the reactor inner wall-surface made of anodically-oxidized aluminum. Depending on preceding processes prior to the H2/N2 plasma process, N and H atom densities decreased for a nitrided wall surface, while no change occurred for a hydrogenated surface. Thus, the process history was revealed in the loss-properties of atoms on the reactor wall-surfaces. Suppressing the temporal variations in the gas-phase atom density is crucially important for realizing the precise control of the material processing with a high reproducibility.