AVS 45th International Symposium
    Vacuum Metallurgy Division Tuesday Sessions
       Session VM+TF-TuM

Invited Paper VM+TF-TuM1
Deposition, Structure, and Properties of Superlattice Thin Films

Tuesday, November 3, 1998, 8:20 am, Room 328

Session: Advances in Hard and Superhard Coatings
Presenter: S.A. Barnett, Northwestern University
Authors: S.A. Barnett, Northwestern University
A. Madan, Northwestern University
P. Yashar, Northwestern University
I. Kim, Northwestern University
Correspondent: Click to Email
In this talk, superlattice thin films with nitride/nitride, metal/nitride, and oxide/oxide layers are described. Processing issues for high-rate superlattice deposition using reactive magnetron sputtering are described, including reactive-gas partial pressure control for obtaining stoichiometric layers and use of substrate bias to achieve ion bombardment densification. The stability of the layered structures at elevated temperatures is described; it is found that nanometer thick layers can exhibit excellent stability in cases where the relevant phase diagram shows little miscibility. The key materials criteria for obtaining hardness enhancements are delineated by making comparisons between different superlattice systems. Hardness predictions based on dislocation glide mechanisms are discussed. For cases where both superlattice layers have the same structure, a substantial difference between the layer shear moduli is required to limit dislocation motion and thereby strengthen the material. Superlattices where the layers have different structures, such that there is no common dislocation glide system, can also exhibit large hardness enhancements.