High‐resolution monochromated XPS of poly(methyl methacrylate) thin films on a conducting substrate

Abstract

Abstract Experiments directed towards obtaining high‐resolution XPS data for spin‐cast thin films of poly(methylmethacrylate) (PMMA) on a silicon substrate are described. Thickness‐dependent charging and the effect of vertical differential charging on spectral resolution are demonstrated, and the conditions required for optimum spectral resolution are established. Evidence is provided for an interaction between the carboxyl group of PMMA and the substrate, and for an interaction between carboxyl groups of the polymer. The latter is manifested as a dependence of the CO and CO C Is chemical shift on polymer tacticity. Four different curve‐fitting schemes (nominally 1:1:3, 1:1:1:2, 1:1:2:1 and 1:1:1:1:1 component area ratios) are applied to the high‐resolution C Is data. The three‐peak scheme does not provide a good fit to the data, but the envelope is adequately described by any one of the three remaining possibilities.