A study on gas desorption from inductively coupled plasma chamber wall by optical emission spectroscopy method

Summary form only given. In nitriding stainless steel experiments in RF inductively coupled plasma chamber, optical emission spectroscopy (OES) measurements were carried out within the visible range. The gases used for these experiments were pure nitrogen and hydrogen, while the emission was dominated by nitrogen species and almost independent of their composition ratios, provided that the other discharge conditions remained unchanged. The gas desorbed from both the inner wall of vacuum chamber and substrate-holder surface produced significant influence on the emission intensities and even caused the discharge to be unstable to some extent. To reduce the effect of desorption on discharge, a series of experiments were carried out namely, without any conditioning, zero time-gap conditioning, and 1 hour time-gap conditioning prior to nitriding SS (stainless steel) 304 samples. The characteristics of the plasma, observed by OES method, at different conditioning conditions and their effects on the quality of nitrided layers will be reported in detail.