The influence of non-uniform target poisoning on the energy distributions of atoms sputtered in a reactive DC magnetron discharge

The lateral variation of the energy distributions of sputtered Ti atoms has been investigated by energy resolved mass spectrometry during reactive DC magnetron sputter deposition of TiN from a Ti target in an argon/nitrogen gas mixture. The mass spectrometer was placed at substrate position and scanned across the target surface of a two inch planar circular magnetron. The energy distribution of sputtered particles is influenced by their origin, showing significant differences between the center and the erosion zone of the target. The results are interpreted in terms of laterally different states of target poisoning, which results in a variation of the surface binding energy. The reactive gas target coverage as derived from the sputtered energy distributions is in reasonable agreement with predictions from model calculations.