Growth of epitaxial TiN films deposited on MgO(100) by reactive magnetron sputtering: The role of low-energy ion irradiation during deposition

L. Hultman*, S. A. Barnett, J. E. Sundgren, J. E. Greene

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

114 Scopus citations


Plan-view and cross-sectional transmission electron microscopy have been used to investigate the role of low-energy ion irradiation in controlling the defect structure of epitaxial TiN(100). The films were deposited by reactive magnetron sputter deposition onto MgO(100) substrates at film growth temperatures Ts between 550 and 850°C (0.26 to 0.35 of the melting point of TiN in K) and negative substrate biases Vs between 0 and 500 V. Sputtering was carried out in pure N2 atmospheres, the energy per N ion incident at the film surface was ∼ eVs 2 (N2+ was the predominant ionic species), the incident ion to thermal-atom flux ratio for films grown with Vs≥100 V was ∼1.3, and the deposition rate was ∼1 monolayer s-1 (1.3 μm h-1). The primary defects observed in the films were dislocation loops on {111} planes. The number density nd of these loops decreased with increasing Ts (e.g., for Vs=0, nd ranged from 5×1012cm-2 at 550°C to 1.5×1010cm-2 at 850°C). However, nd also decreased rapidly with increasing Vs at constant Ts until a minimum defect density was attained at Vs*(Ts) after which nd incre ased again. Films grown at Ts≥750°C and Vs=Vs* ≅ 300 V were essentially free of dislocation loops. On the other hand, films grown with T s<650°C and Vs≥400V (i.e., Vs > Vs*) exhibited very high dislocation loop densities, ≥5×1012cm-2, together with the preci itation of N2 gas bubbles. The net effect of ion irradiation on film microstructure depended upon a competition between the defect annihilation rate due to enhanced adatom mobilities during deposition and the collisionally-induced defect formation rate. The residual defect density was thus a function of both Ts and Vs. Under the proper growth conditions, ion irradiation led to a reduction in dislocation loop densities by more than 5 orders of magnitude. Cross-sectional micrographs of multilayer films grown as a function of Vs at constant Ts showed that nd increased or decreased (depending upon the direction of the change in Vs) abruptly and reversibly.

Original languageEnglish (US)
Pages (from-to)639-656
Number of pages18
JournalJournal of Crystal Growth
Issue number3-4
StatePublished - Oct 2 1988

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Inorganic Chemistry
  • Materials Chemistry


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