Effects of the temperature and beam parameters on depth profiles in X-ray photoelectron spectrometry and secondary ion mass spectrometry under C60(+)-Ar(+) cosputtering

Hua-Yang Liao; Meng-Hung Tsai; Wei-Lun Kao; Ding-Yuan Kuo; Jing-Jong Shyue

doi:10.1016/j.aca.2014.08.044

Effects of the temperature and beam parameters on depth profiles in X-ray photoelectron spectrometry and secondary ion mass spectrometry under C60(+)-Ar(+) cosputtering

Anal Chim Acta. 2014 Dec 10:852:129-36. doi: 10.1016/j.aca.2014.08.044. Epub 2014 Aug 23.

Authors

Hua-Yang Liao¹, Meng-Hung Tsai², Wei-Lun Kao¹, Ding-Yuan Kuo¹, Jing-Jong Shyue³

Affiliations

¹ Research Center for Applied Science, Academia Sinica, Taipei 115, Taiwan.
² Department of Materials Science and Engineering, Nation Taiwan University, Taipei 106, Taiwan.
³ 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.

PMID: 25441889
DOI: 10.1016/j.aca.2014.08.044

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.

Keywords: C(60)(+)-sputtering; Cluster ion; Depth profiles; Secondary ion mass spectrometry (SIMS); Temperature effect; X-ray photoelectron spectrometry (XPS).