Secondary Ion Mass Spectrometry (SIMS) employing an SF5+ polyatomic primary ion source was used to depth profile through various polymeric biomaterials at a series of temperatures from -125 oC to 150 oC. The depth profile characteristics (e.g. interfacial widths, sputter rates, damage cross sections, and overall secondary ion stability) were monitored as a function of temperature. It was found that at low temperatures, the secondary ion stability increased considerably for most materials. In addition, the interfacial widths were significantly lower. Corresponding AFM images indicated that there was also decreased sputter induced topography at these lower temperatures in poly(methyl methacrylate ) (PMMA) samples. Higher temperatures were typically correlated with increased sputter rates. However, the improvements in interfacial widths and overall secondary ion stability were not as prevalent as was observed at low temperatures. The importance of glass transition temperature (Tg) on the depth profile characteristics was also apparent. Resulting PMMA depth profile characteristics were compared with that of poly(lactic acid) (PLA), considered to be one of the more successful cases of polymer depth profiling (very low damage cross-sections, high sputter rates, small interface widths). The resulting interface widths and damage cross sections of PMMA at cryogenic temperatures were comparable to PLA at room temperature.
Citation: Applied Surface Science
Pub Type: Journals
AFM, cluster SIMS, depth profiles, ESCA, polymers, SF5+, SIMS, TOF, XPS