A STUDY OF THE PICOSTRUCTURE OF SPUTTERED ZRN FILMS

Stoichiometric zirconium nitride films deposited onto cemented carbide and stainless steel substrates as a function of the applied substrate bias were studied by X-ray diffraction (XRD Bragg-Brentano goniometer) and positron annihilation spectroscopy (PAS). Microhardness and color measurements were also carried out. The results at low bias levels show that the crystal lattice has no deviant behavior in the strain distribution or lattice parameters; such differences which are observed in the latter are due to the X-ray elastic constants. Shear stresses are found on the (h00) family of planes and probably on the (hhh) family at bias levels more negative than -70 V. The microhardness and residual stress are then constant. The PAS data indicate that the vacancy defect fraction is below the limit of detection at bias levels less negative than approximately -80 V; a low concentration of vacancies exists at more negative bias values. The color of the films is not affected by the bias applied during deposition, and is only slightly affected by annealing when deposited at low bias values. In view of the change in lattice parameters on annealing, it is concluded that the results do not correspond with those expected from the simple ionic model.