| AVS 56th International Symposium & Exhibition | |
| Applied Surface Science | Thursday Sessions |
| Session AS-ThA |
| Session: | Chemical State Depth Profiling |
| Presenter: | S.J. Hutton, Kratos Analytical Ltd, UK |
| Authors: | S.J. Hutton, Kratos Analytical Ltd, UK I.W. Drummond, Kratos Analytical Ltd, UK S.C. Page, Kratos Analytical Ltd, UK C.J. Blomfield, Kratos Analytical Ltd, UK |
| Correspondent: | Click to Email |
The sputter profiling of inorganic materials during X-ray Photoelectron Spectroscopy (XPS) is a well established technique to investigate quantitative chemical composition variations with depth. Until recently XPS sputter depth profiling of organic materials has suffered from several seemingly intractable problems, not least the significant ion induced surface damage. Secondary Ion Mass Spectroscopy (SIMS) of organic materials using noble gas or liquid metal ion sources suffered related problems. These problems have largely been overcome for the SIMS analysis of a wide range of organic materials by the introduction of cluster ion sources such as SF5 and C60. Advantages of cluster sources include an increase in secondary ion yield over conventional mono-atomic sources and a reduction in beam induced damage of the surface.
Following on from these innovations in SIMS, cluster ion sources have been utilised for XPS sputter profiling of organics. These sources have been shown to significantly reduce ion induced surface damage of organic materials as measured by XPS thus making the XPS sputter profiling of organic materials feasible.
In this study we investigate the sputter profiling of several model polymer films using a new polyaromatic hydrocarbon (PAH) (coronene) cluster ion source. Initial results demonstrate that yield volumes per incident ion are dependent on the nature of the polymer, with approximate values of: 90 nm3 for poly(lactic-co-glycolic acid) (PLGA); 117 nm3 for polyacrylic acid (PAA); and 142 nm3 for polylactic acid (PLA). Other polymers, such as polystyrene (PS), do not appear to be sputtered by cluster sources under the currently reported conditions. Early results also indicate that various experimental parameters, such as incident beam energy, affect the sputter yield and amount of ion beam induced surface damage.
Clearly there is a need to investigate the various parameters which may influence ion yields and damage with the aim of optimising sputtering conditions for a range of organic materials. The work presented here attempts to elucidate the effects of variables such as ion incident energy; ion beam angle of incidence; sample temperature and ion mass on the sputtering performance of the aforementioned PAH ion source on several thin polymer films.