title: Effects of the temperature and beam parameters on depth profiles in X-ray photoelectron spectrometry and secondary ion mass spectrometry under C60(+)-Ar(+) cosputtering.
abstract: Polymethylmethacrylate (PMMA) is widely used in various fields, including the semiconductor, biomaterial and microelectronic fields. Obtaining the correct depth profiles of PMMA is essential, especially when it is used as a thin-film. There have been many studies that have used earlier generation of cluster ion (SF5(+)) as the sputtering source to profile PMMA films, but few reports have discussed the use of the more recently developed C60(+) in the PMMA sputtering process. In this study, X-ray photoelectron spectroscopy (XPS) and dynamic secondary ion mass spectroscopy (D-SIMS) were used concurrently to monitor the depth profiles of PMMA under C60(+) bombardment. Additionally, the cosputtering technique (C60(+) sputtering with auxiliary, low-kinetic-energy Ar(+)) was introduced to improve the analytical results. The proper cosputtering conditions could eliminate the signal enhancement near the interface that occurred with C60(+) sputtering and enhance the sputtering yield of the characteristic signals. Atomic force microscopy (AFM) was also used to measure the ion-induced topography. Furthermore, the effect of the specimen temperature on the PMMA depth profile was also examined. At higher temperatures (+120°C), the depolymerization reaction that corresponded to main-chain scission dominated the sputtering process. At lower temperatures (-120°C), the cross-linking mechanism was retarded significantly due to the immobilization of free radicals. Both the higher and lower sample temperatures were found to further improve the resulting depth profiles.
authors.affiliation: Research Center for Applied Science, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Hua-Yang
authors.initials: HY
authors.lastname: Liao
authors.affiliation: Department of Materials Science and Engineering, Nation Taiwan University, Taipei 106, Taiwan.
authors.forename: Meng-Hung
authors.initials: MH
authors.lastname: Tsai
authors.affiliation: Research Center for Applied Science, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Wei-Lun
authors.initials: WL
authors.lastname: Kao
authors.affiliation: Research Center for Applied Science, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Ding-Yuan
authors.initials: DY
authors.lastname: Kuo
authors.affiliation: Research Center for Applied Science, Academia Sinica, Taipei 115, Taiwan; Department of Materials Science and Engineering, Nation Taiwan University, Taipei 106, Taiwan. Electronic address: shyue@gate.sinica.edu.tw.
authors.forename: Jing-Jong
authors.initials: JJ
authors.lastname: Shyue
keywords: C(60)(+)-sputtering; Cluster ion; Depth profiles; Secondary ion mass spectrometry (SIMS); Temperature effect; X-ray photoelectron spectrometry (XPS)