In situ scanning tunneling microscopy studies of the evolution of surface morphology and microstructure in epitaxial TiN(001) grown by ultra-high-vacuum reactive magnetron sputtering

Brian W. Karr, I. Petrov, P. Desjardins, David G. Cahill, J. E. Greene

Research output: Contribution to journalArticlepeer-review

Abstract

The group IV-B transition metal nitride TiN is widely employed as a wear-resistant coating on mechanical components and as a diffusion barrier in microelectronic devices. We use the epitaxial growth of TiN as a model system for insight on the evolution of surface morphology and microstructure in more complex polycrystalline films. Atomically-flat MgO(001) substrates, prepared by air annealing at 950°C for 12 h, are verified by atomic force microscopy (AFM). Epitaxial TiN layers are grown by reactive magnetron sputter deposition in pure N2 at 650 ≤ Ts ≤ 750°C. Scanning tunneling microscopy (STM) results show that the development of surface morphology is dominated by growth mounds with an aspect-ratio of ≈ 0.006; both the roughness amplitude and average separation between mounds follow an approximate power law dependence on film thickness, tγ, with γ = 0.25 ± 0.07. The films grow in a two-dimensional multilayer mode in which island edges exhibit dendritic geometries characteristic of limited step-edge mobility. Transmission electron microscopy (TEM) shows that the films are epitaxial with dislocation loops on {111} planes and 〈001〉 misfit dislocations at the interface. Low-energy N+2 ion irradiation during film growth leads to surface smoothing with the smoothest layers, having a surface width of ≅ 0.22 nm, obtained with Vs = 43 V. Increasing Vs ≥ 43 V leads to surface roughening with decreased in-plane length scales.

Original languageEnglish (US)
Pages (from-to)403-408
Number of pages6
JournalSurface and Coatings Technology
Volume94-95
DOIs
StatePublished - Oct 1997

Keywords

  • Epitaxial titanium nitride
  • Reactive magnetron sputtering
  • Scanning tunneling microscopy

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Condensed Matter Physics
  • Surfaces and Interfaces

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