Pressure dependence of singly and doubly charged ion formation in a HiPIMS discharge

Generation of singly charged Ar + and Ti +, doubly charged Ar 2 + and Ti 2 +, and of Ar 2 + and Ti 2 + dimer ions in a high power impulse magnetron sputtering (HiPIMS) discharge with a Ti cathode was investigated. Energy-resolved mass spectrometry was employed. The argon gas pressures varied between 0.5 and 2.0 Pa. Energy spectra of monomer ions are composed of low- and high-energy components. The energetic position of the high-energy component is approximately twice as large for doubly charged ions compared to singly charged ions. Intensities of Ar 2 + and Ti 2 + dimer ions are considerably smaller during HiPIMS compared to dc magnetron sputtering.