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

Invited Paper VM+TF-TuM5
Energetics of Cubic Boron Nitride Deposition

Tuesday, November 3, 1998, 9:40 am, Room 328

Session: Advances in Hard and Superhard Coatings
Presenter: R. Clarke, University of Michigan
Authors: R. Clarke, University of Michigan
D. Litvinov, University of Michigan
Correspondent: Click to Email
As a structural analog of diamond, cubic boron nitride (c-BN)is attracting increasing interest as an ultrahard coating material. An ongoing challenge towards exploiting the favorable properties of c-BN, including its chemical intertness and high thermal conductivity, is its tendency to build up substantial levels of stress at practically useful thicknesses of a few microns. If this stress is not remediated, it can lead to loss of adhesion. In this talk we present recent results demonstrating our approach to characterizing and controlling the intrinsic stress in c-BN coatings. Through an improved understanding of the kinetics of c-BN growth, using dc-biased ECR-assisted sputtering, we have achieved highly adhesive coatings on Silicon with film thicknesses up to 2µm. A novel multibeam optical wafer curvature method allows us to track, in-situ, the stress build-up during growth, and to implement 'reduced-bias' conditions after the initial nucleation and coalescence of c-BN islands. Reducing the kinetic energy of arriving nitrogen ions in this way (to ~ 50eV), leads to fewer defects in the film, reduced levels of stress, and higher growth rates, compared to values obtained at bias conditions necessary to initiate c-BN growth. Work partly supported by ONR grant N00014-94-J-0763, and by k-Space Associates Inc.