TOF-SIMS study of modified polymer surfaces

Abstract

Amongst various surface modification techniques, plasma source ion implantation (PSII) has been used to study the effect of modification on polymer surface properties. Polyimide foils were exposed in an inductively coupled rf (13.56 MHz) plasma system while applying a negative high voltage pulse to the sample stage. The influence of low-pressure plasmas of oxygen, nitrogen, or inert gases on the chemical composition, topography, and electrical properties of polyimide surfaces was studied in detail. The ion energy was varied from 10 to 50 keV for the PSII experiments. Depending on the ion energy, ion dose, and ion species, the surface resistivity of the film was reduced by several orders of magnitude. Ion bombarded layers were characterized by TOF-SIMS, SEM, and AFM. TOF-SIMS spectra of the modified polyimides showed an enhancement of the low mass fragments and carbon species. Electrical property improvement, as measured by high resistance electrometer, was linked to the chemical changes occurring at the polyimide surface, as identified by TOF-SIMS depth profile. (C) 2004 Elsevier B.V. All rights reserved.