Ion formation in an argon and argon-oxygen gas mixture of a magnetron sputtering discharge

Formation of singly and doubly charged Ar q + and Ti q + ( q  = 1,2) and of molecular Ar 2 + , ArTi + , and Ti 2 + ions in a direct current magnetron sputtering discharge with a Ti cathode and argon as working gas was investigated with the help of energy-resolved mass spectrometry. Measured ion energy distributions consist of low-energy and high-energy components resembling different formation processes. Intensities of Ar 2 + and ArTi + dimer ions strongly increase with increasing gas pressure. Addition of oxygen gas leads to the formation of positively charged O + , O 2 + , and TiO + and of negatively charged O − and O 2 − ions.