Incident angle dependence in polymer TOF-SIMS depth profiling with C 60 ion beams

Abstract

Cluster ions such as C60+ are well used as the sputtering ions for polymer depth profiling. The molecules of analyte surfaces are occasionally damaged by the ion bombardment during sputtering, leading to a loss of the molecular information. In order to obtain a proper polymer depth profile, sputtering conditions shall be optimized, however, they have not been investigated sufficiently. In this study, incident angle dependence was investigated at the angle from 48° to 76° with respect to the surface normal. Samples used were the bulk polycarbonate (PC), bulk polystyrene (PS), and Irganox1010/Irganox3114 organic multi layer film. Irganox3114 layers were deposited at the several depths in the Irganox1010 film as markers to evaluate the interface resolution. Characteristic TOF-SIMS spectra from PC and PS were retained even after sputtering hundreds of nanometers at 76°, although the loss of the molecular information due to carbon deposition and/or damage accumulation was observed at 48°. From the depth profile of Irganox1010/Irganox3114, significant improvement of interface resolution was obtained at 76° over that at 48°. This work indicates that glancing angle sputtering clearly becomes one of the approaches to optimize C 60 polymer depth profiling. © 2009 The Surface Science Society of Japan.