ION-BEAM-ASSISTED DEPOSITION OF ALN MONOLITHIC FILMS AND AL ALN MULTILAYERS - A COMPARATIVE-STUDY/

Monolithic AlN films and Al/AlN multilayers with periodic thickness ra nging from 6 to 24 nm were synthesized by ion beam assisted deposition (IBAD) from electron beam evaporated aluminum and a nitrogen ion beam . During deposition of the multilayers, the nitrogen ion beam was alte rnately switched on and off, corresponding to AlN and Al sublayer depo sition periods, respectively. A comparative study, with respect to mic rostructure and mechanical properties, was conducted both between the monolithic AlN films prepared with varied IBAD process parameters, and between the Al/AlN multilayers and their constituent monolithic AlN f ilms. Two fundamental IBAD parameters of ion energy (100-500 eV) and i on-to-atom arrival rate ratio (1.45-3.60) were found to play important roles in the properties of the monolithic AlN films, Some contradicti ons in this respect appearing in the literature are discussed. When co mparing the Al/AlN multilayers with their constituting monolithic AlN films, a substantial improvement of the mechanical properties has been observed only at low ion energies and ion-to-atom arrival rate ratios . Possible reasons are discussed. (C) 1998 Elsevier Science S.A.