Interaction of polymeric Si:C:H films with copper substrates and with deposited Cu adatoms

Polymeric Si:C:H films stable to 800 K in UHV, were formed on Cu or Ta substrates by electron bombardment. Vinyltrimethylsilane (VTMS) vapor was condensed onto a cold (<90 K) Cu substrate under UHV conditions and exposed to a 500 eV electron beam in order to cross-link the molecules through the vinyl groups in the precursor. The formed Si:C:H films have a chemical structure and stoichiometry very close to that of VTMS molecular precursor. The film thickness after annealing to 300 K is linearly proportional to total electron fluence on the condensed VTMS multilayer. The interactions between deposited Cu and Si:C:H films were also studied using DC magnetron Cu sputtering. XPS Cu core level and X-ray excited Cu(L3VV) Auger spectra indicate that sputter-deposited Cu interacts weakly with the polymeric film, displaying no charge transfer between Cu and substrate film, and growth by three-dimensional island formation. Upon annealing above 300 K, the Cu(2p3/2)/Si(2p) XPS intensity ratio decreases, but the Cu(2p3/2)/Cu(3p) intensity ratio remains constant. This indicates that annealing above 300 K induces Cu agglomeration and negligible Cu diffusion into the substrate.