Mass Spectrometric Study of Neutral Particles Sputtered from Cu by 0- to 100-eV Ar Ions

A low-pressure magnetically confined argon arc discharge was used in a mass spectrometer ion source to study low-energy (0–100 eV) sputtering of polycrystalline copper. Target bombarding ion current densities ranged from 60–200 μA/cm2. Neutral particles were studied. Cu atoms and Cu2 molecules were detected. The mass ratio of analyzed Cu2 molecules to Cu atoms increased with bombarding ion energies to about 5½% at ion energies of 100 eV. Target voltages for appearance of Cu atoms and Cu2 molecules were − 19 and − 50 V, respectively. No Cu3 molecules were detected; if they were present, it was estimated that the ratio 189Cu3 to 63Cu is less than 0.09%. The method has been found to be promising for the study of neutral particles in low-energy sputtering. Yield curves agree well with results of other observers; sensitivities of 7×10−4 atoms/ion were attained, and this figure can be improved.