INITIAL-STAGE OF PREFERENTIAL SPUTTERING IN CU-PT ALLOY STUDIED BY SPUTTERED NEUTRALS MASS-SPECTROMETRY

Nonresonant multiphoton ionization sputtered neutrals mass spectrometr y (NRMPI-SNMS) was used to measure a codeposited Cu-Pt alloy film to e lucidate how preferential sputtering proceeds with ion bombardment. Fo r this, Ne have newly developed a compact coevaporator which enables p reparation of Cu-Pt alloy him of homogeneous composition from the surf ace to the bulk in a specimen chamber. The present study has revealed that the ratio of sputtered Cu atoms to Pt atoms is similar to 9.3 at the very initial stage of sputtering for a Cu-Pt alloy surface of whic h surface composition under ion bombardment is assessed to be Cu(88 at .%)-Pt at the topmost surface together with by the successive atomic l ayers of homogeneous composition of Cu(68.2 at.%)-Pt. This result has clearly indicated that Cu atoms are preferentially sputtered through a tomic collisions caused entirely by the kinetic process of sputtering.