Investigation of the Negative Ions in Ar/O2 Plasma of Magnetron Sputtering Discharge with Al:Zn Target by Ion Mass Spectrometry

Abstract

AbstractThe 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 $\phi _{{\rm O}_{2} } $ 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−, ${\rm O}_{2}^{{-} } $, AlO−, ${\rm AlO}_{2}^{{-} } $, ZnO−, ${\rm ZnO}_{2}^{{-} } $, and ${\rm AlO}_{3}^{{-} } $ 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. magnified image