Spatially resolved optical emission studies of pulsed D.C. plasmas for TiN deposition by unbalanced magnetron sputtering

Two-dimensional images of optical emission intensities from plasmas, captured by an intensified charge coupled device (ICCD) camera at the viewing window of a plasma chamber, could be interpreted as the spatial distributions of excited species or ions. We report the use of ICCD images for the optical emission study of a pulsed D.C. plasma for TiN coatings by an unbalanced magnetron sputtering. The images through specific pass filters discerned the differences of the optical emission distribution of corresponding species. The Abel inversion was performed to convert the line-integrated intensity values, measured by ICCD, to the emissivity data. For the calibration of intensity measurement with an ICCD, the ratio of heights among the peaks in a spectral graph measured by a monochromator was used as the reference data. Especially the comparison between N2 and Ti emission images of the region near the substrate surface is noticeable. The significant increase in the ratio of N2 to Ti intensity with increasing nitrogen gas flow rate implied the transition of deposition mode.