Investigation of the negative ions in Ar/O₂ plasma of magnetron sputtering discharge with Al:Zn target by ion mass spectrometry

The magnetron sputtering discharge used to deposit aluminum-doped zinc oxide was analyzed by energy-resolved ion mass spectrometry. The flux of negative ions was measured at three radial positions in the plane of the substrate holder. The oxygen flow θO₂ was varied from 0 to 17 sccm to investigate the discharge in all operation modes, i.e., metallic, transition, and oxide mode of sputtering. The existence of negative ions was determined from the energy spectra. Main attention was devoted to the investigation of O^-, O₂ ^-, AlO^-, AlO₂ ^-, ZnO^-, ZnO₂ ^-, and AlO₃ ^- negative ions and correlations of their intensities in the energy spectrum with discharge parameters (cathode voltage, magnetron power, and gas pressure). It was found that (i) intensities of negative ions exhibit maxima in the vicinity of transition between the metallic and transition mode of sputtering and (ii) in the oxide mode intensities of these ions are saturated. In this paper, we investigate the creation and the flux of negative ions and radicals in Ar + O₂ mixture by the unbalanced magnetron equipped with Al:Zn (2 wt%) alloyed target. The existence of negative ions O^-, AlO^-, ZnO^-, and is determined from the energy spectra. The most intense flux of negative ions is located above the race-track center of sputtered target.