title: Molecular dynamic-secondary ion mass spectrometry (D-SIMS) ionized by co-sputtering with C60+ and Ar+.
abstract: Dynamic secondary ion mass spectrometry (D-SIMS) analysis of poly(ethylene terephthalate) (PET) and poly(methyl methacrylate) (PMMA) was conducted using a quadrupole mass analyzer with various combinations of continuous C(60)(+) and Ar(+) ion sputtering. Individually, the Ar(+) beam failed to generate fragments above m/z 200, and the C(60)(+) beam generated molecular fragments of m/z ~1000. By combining the two beams, the auxiliary Ar(+) beam, which is proposed to suppress carbon deposition due to C(60)(+) bombardment and/or remove graphitized polymer, the sputtering range of the C(60)(+) beam is extended. Another advantage of this technique is that the high sputtering rate and associated high molecular ion intensity of the C(60)(+) beam generate adequate high-mass fragments that mask the damage from the Ar(+) beam. As a result, fragments at m/z ~900 can be clearly observed. As a depth-profiling tool, the single C(60)(+) beam cannot reach a steady state for either PET or PMMA at high ion fluence, and the intensity of the molecular fragments produced by the beam decreases with increasing C(60)(+) fluence. As a result, the single C(60)(+) beam is suitable for profiling surface layers with limited thickness. With C(60)(+)-Ar(+) co-sputtering, although the initial drop in intensity is more significant than with single C(60)(+) ionization because of the damage introduced by the auxiliary Ar(+), the intensity levels indicate that a more steady-state process can be achieved. In addition, the secondary ion intensity at high fluence is higher with co-sputtering. As a result, the sputtered depth is enhanced with co-sputtering and the technique is suitable for profiling thick layers. Furthermore, co-sputtering yields a smoother surface than single C(60)(+) sputtering.
authors.affiliation: Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Yun-Wen
authors.initials: YW
authors.lastname: You
authors.forename: Hsun-Yun
authors.initials: HY
authors.lastname: Chang
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Lin
authors.forename: Che-Hung
authors.initials: CH
authors.lastname: Kuo
authors.forename: Szu-Hsian
authors.initials: SH
authors.lastname: Lee
authors.forename: Wei-Lun
authors.initials: WL
authors.lastname: Kao
authors.forename: Guo-Ji
authors.initials: GJ
authors.lastname: Yen
authors.forename: Chi-Jen
authors.initials: CJ
authors.lastname: Chang
authors.forename: Chi-Ping
authors.initials: CP
authors.lastname: Liu
authors.forename: Chih-Chieh
authors.initials: CC
authors.lastname: Huang
authors.forename: Hua-Yang
authors.initials: HY
authors.lastname: Liao
authors.forename: Jing-Jong
authors.initials: JJ
authors.lastname: Shyue