AVS 46th International Symposium
    Vacuum Metallurgy Division Wednesday Sessions
       Session VM-WeM

Invited Paper VM-WeM1
Microstructural and Surface Morphological Evolution at the Atomic Scale during the Growth of Polycrystalline TiN: a TEM, XRD, HT-STM, and Modeling Study

Wednesday, October 27, 1999, 8:20 am, Room 620

Session: Advanced Surface Treatments and Coatings
Presenter: I. Petrov, University of Illinois, Urbana
Authors: I. Petrov, University of Illinois, Urbana
S. Kodambaka, University of Illinois, Urbana
P. Desjardins, University of Illinois, Urbana
A. Vailionis, University of Illinois, Urbana
V. Petrova, University of Illinois, Urbana
J.E. Greene, University of Illinois, Urbana
L. Hultman, Linköping University, Sweden
G. Gilmer, Lucent
Correspondent: Click to Email
TiN is widely used as a diffusion barrier in microelectronics, as a hard wear resistant coating on cutting tools, and as a corrosion and abrasion resistant layer on optical components. Even though its diffusion barrier and elastic properties are known to be extremely anisotropic, little is known regarding the mechanisms and reaction paths leading to the development of preferred orientation in polycrystalline TiN layers deposited by PVD. We have used in-situ temperature-dependent STM measurements during deposition and post-annealing, detailed post-deposition microstructural analyses, and modeling to provide atomic-scale insights into microstructural and surface morphological evolution during TiN film growth. The results show that TiN layers grown at low temperatures (@<=@ 450°C, T@sub s@/T@sub m@ = 0.20) exhibit competitive texture evolution with a columnar 111 "kinetically-limited" texture eventually becoming dominant. The columns are narrow with inter- and intracolumnar porosity and facetted surfaces. Higher growth temperatures or the use of high incident N@super +@@sub 2@/Ti flux ratios (> 5) with low ion energies (20 eV) result in non-competitive growth with the development of a fully dense essentially complete 002 preferred orientation from the initial monolayer. The above microstructural results can be understood qualitatively assuming that the activation energy E@sub s@ for surface diffusion and the Ehrlich barrier E@sub b@ at descending step edges are larger on 111 surfaces than on 002. Using this, together with the assumption that pseudomorphic forces (i.e., local epitaxy) dominate once island orientation is determined locally, the general features observed in the experiments outlined above can be replicated using kinetic Monte Carlo simulations. The in-situ STM observations of the dynamics of island growth and decay also provide important additional insights into the atomic-scale growth of TiN and related transition-metal nitrides.