ROLE OF Ar ⁺ , CH₄ ⁺ , O₂ ⁺ AND BACKSCATTERED Pb ⁺ IONS DURING Nb/OXIDE/PbAuIn EDGE JUNCTION FABRICATION.

This paper reports in-situ measurements of ion currents, energies, and species present during rf plasma sputtering of niobium, niobiumcarbide growth, and niobium oxide growth in the Josephson junction fabrication process. Backscattered metal species sputtered off the cathode are also reported. The above ion information is used to support a simple model for oxygen ion beam induced niobium oxide growth for tunnel barriers. The results are in reasonable agreement with ion beam oxidation studies.