Carbon film growth on model MLM cap layer: interaction of selected hydrocarbon vapor with Ru(10-10) surface

The aim of this work is to explore the thermal and non-thermal interaction of toluene, benzene and isobutene vapor with a crystalline Ru(10-10) surface, a model surface for Ru capping layers used in EUV lithography. Our main objective is to provide insights into the basic processes that affect the reflectivity of Ru-coated Mo/Si multilayer mirrors that are exposed to EUV radiation. A low energy electron beam is employed to mimic excitations initiated by EUV radiation. Temperature programmed desorption (TPD), x-ray photoelectron spectroscopy (XPS), low energy ion scattering (LEIS), and electron-stimulated desorption (ESD) are used to analyze the surface reactions. Pyrolysis of a chemisorbed hydrocarbon layer on the Ru surface leads to the dehydrogenation and buildup a self-limited carbon monolayer. Carbon film growth on the Ru(10-10) crystalline surface under 100 eV electron bombardment in hydrocarbon vapor is measured over a range of pressures and temperatures near 300 K. The carbon growth rate is ~10 times higher in the presence of toluene vapor than in the presence of benzene or isobutene vapor. The estimations of the adsorption energy, the steadystate coverage of the molecules on the surface and the cross-sections for electron-stimulated dissociation are presented. A graphene-like carbon layer is probed as possible way to reduce the surface contamination rate.