Atomistic simulation of the vapor deposition of Ni/Cu/Ni multilayers: Incident adatom angle effects

Molecular dynamics simulations have been used to explore the effects of inc ident adatom angle upon the atomic scale structure of Ni/Cu/Ni multilayers grown by vapor deposition under controlled incident atom energy conditions. For incident atom energies of 1 eV or less, increasing the incident angle increased interfacial roughness, resulted in void formation in the nickel l ayer, and intermixing at the interfaces between metal layers. The interfaci al roughness that formed during low impact energy oblique angle deposition was significantly reduced by substrate rotation during growth. However, rot ation had no beneficial effects upon interfacial mixing. The use of a highe r incident atom energy (greater than or equal to 5 eV/atom) resulted in fla tter interfaces and eliminated voids under oblique incidence conditions, bu t it also caused more severe interfacial mixing by an atomic exchange mecha nism. When low (thermal) impact energies were used to deposit the first few monolayers of each new metal layer, intermixing by the exchange mechanism during subsequent hyperthermal energy deposition could be significantly red uced. Using this modulated incident energy growth strategy, films with litt le interfacial roughness and intermixing could be grown over a wide range o f incident angles with or without substrate rotation. (C) 2000 American Ins titute of Physics. [S0021- 8979(00)01301-3].