MASS-SPECTROMETRIC ION ANALYSIS IN THE SPUTTERING OF OXIDE TARGETS

Species and energies of impinging ions at the substrate during sputtering were analyzed with a quadrupole mass spectrometer combined with an energy analyzer for different targets of Y1Ba2Cu3O7-x (YBCO), InSnO + 5wt %SnO (ITO), ZnO, Pb,Zr0.5Ti0.5O3 (PZT), and Ba1Cu2Ox (BCO). In every target the argon positive ion flux was most intensely observed. Relative intensities of the dominant positive ionized sputtered atoms, normalized by the argon positive ion flux, were 0.3% to 4.5%. The dominant negative ion flux was oxygen negative ions (O-16-). Relative intensities were 13% and 18% for YBCO and BCO, respectively. For ITO, ZnO, and PZT, however, they were 0.26% to 0.36%. These results qualitatively agreed with the model of negative-ion formation based on ionization potential and electron affinity values. Emission of a large amount of the oxygen negative ions from the target was a distinguishing feature of Ba containing oxide targets.