Molecular depth profiling of polystyrene by electrospray droplet impact

The molecular depth profiling of polymer by the electrospray droplet impact (EDI) has been performed. The multiply charged water droplets with kinetic energy of ∼10 6 eV were irradiated on the polystyrene spin coated on silicon wafer. With EDI etching, the ablation of the target is suppressed to a minimal, i.e. the shallow surface etching with nonrecognizable damage on the surface is realized. It was found that EDI/SIMS spectra and EDI/XPS spectra for polystyrene (PS) has shown no damage accumulation on the surface. This indicates that EDI is a unique technique for surface etching of polymer materials without causing any damage to the etched surface.