Enhanced adhesion from high energy ion irradiation

We have found that irradiation of a variety of thin film-substrate combinations by heavy ion beams at energies of mega-electronvolts per atomic mass unit will produce a remarkable enhancement in the adherence of the film. For example, gold films can be firmly attached to soft materials such as Teflon using a 1 MeV beam of protons (1014 cm−2) or helium ions (1013 cm−2) and to harder materials such as silicon (1015 cm−2), quartz (2 × 1015 cm−2) and tungsten (2 × 1014 cm−2) with 0.5 MeV a.m.u.−1 beams of fluorine or chlorine ions. In the case of metal films on semiconductors a low resistance contact results. The mixed layer at the interface is observed to be quite thin (approximately 50 Å or less); for silver on silicon electron diffraction and imaging studies of the interface region reveal the presence of crystalline silver compounds.