Depth Profiling of Polystyrene Using Charged Water Droplet Impact

Abstract

  The molecular depth profiling of polymer by the electrospray droplet impact (EDI) have been performed. The multiply-charged water droplets with kinetic energy of ～10⁶eV were irradiated to a bulk and a spin coated polymer samples. The synthetic polymer as bulk polystyrene (PS) and spin coated PS on Si substrate were adopted as typical polymers. When a target is etched by EDI, the ablation of the target is suppressed to minimal, i.e. the shallow surface etching with non-recognizable damage on the surface is realized. It was found that X-ray photoelectron spectroscopy (XPS) spectra for PS were independent on the irradiation time by EDI. This indicates that EDI is a unique technique for the surface etching of the polymer materials without leaving any damage on the etched surface.