STUDY ON THE INTERNAL-STRESS IN NICKEL FILMS DEPOSITED ONTO SILICON SUBSTRATES BY ION-BEAM AND VAPOR-DEPOSITION (IVD)

The effect of ion irradiation during deposition, in particular the eff ect of the formation of mixing layers at the interface between the fil m and the substrate by ion mixing, on the internal stress in nickel fi lms deposited onto silicon substrates was studied. The nickel films we re prepared on silicon (100) wafers by evaporation of nickel and simul taneous irradiation with inert gas ions (ion beam and vapor deposition method). The energy of inert gas ion bombardment was varied in the ra nge 0.5-10.0 keV. The transport ratios of vapor atoms to inert gas ion s, atoms/ions, to the substrates were constant at 15. The silicon subs trates were kept at a low temperature by a water cooling system. The i nternal stress in the nickel films was determined by measuring the cha nge in curvature of the substrates. From X-ray analysis and annealing experiments, it is considered that one of the main causes of tensile s tress in nickel films prepared on silicon substrates by IVD is the for mation by ion mixing of an Ni2Si layer at the interface.