SECONDARY-ION EMISSION FROM POLYMER SURFACES UNDER AR-BOMBARDMENT(, XE+ AND SF5+ ION)

We investigated the characteristic molecular secondary ion emission fr om polymer surfaces under 10 keV Ar+, Xe+ and SF5+ bombardment. Second ary ion yields of PET, PP, PTFE, PS, PC, PMMA and PEG were determined under static SIMS conditions. Damage cross sections were measured for PS and PC. We applied a time-of-flight mass spectrometer, equipped wit h a pulsed EI-source allowing the application of mass separated primar y ion beams. Spin coated multilayers as well as surfaces of bulk polym ers have been studied. Changing from Ar+ to Xe+ and to SF5+ bombardmen t we found a strong increase of the yield Y (up to a factor of 1000) a nd a much smaller increase in the corresponding damage cross sections sigma (up to a factor of 6) for characteristic molecular secondary ion s. Both effects are more pronounced in the high mass range. The corres ponding increases in secondary ion formation efficiencies ranges betwe en a factor of 5 and 50, depending on the polymer species, the sample preparation and the mass range. Preliminary results for monomolecular overlayers on Ag and Si indicate a similar behaviour of their characte ristic secondary ion emission. (C) 1998 Elsevier Science B.V. All righ ts reserved.