Spatially resolved characterization of a dc magnetron plasma using optical emission spectroscopy

In this work, a reactive argon−nitrogen $\left[{Ar/N}_2\right(10/1\left)\right]$ dc magnetron plasma for sputtering of a chromium (Cr) target is characterized with high spatial resolution by optical emission spectroscopy (OES) using molecular nitrogen emission bands at 0.5 Pa and 100 W. Beside the global gas temperature T _g, the electron temperature T _e, electron density n _e, and the steady-state Cr density n _Cr are also determined spatially resolved using a movable OES setup inside the chamber and Abel inversion. n _e and T _e are found to be consistent with the values measured by a Langmuir probe (LP) within the non-magnetized region along the magnetron axis in a pure Ar plasma for the same process parameters. Finally, a nitrogen content c _N of 4% in the target surface is found for the reactive plasma by matching the mean steady-state chromium density ${\overline{n}}_{Cr}$ measured by OES and calculated from TRIDYN simulations. (paper)