Structural, optical and electrical properties of argon implanted TiN thin films

• Properties of TiN films can be controlled by combining ion irradiation and annealing.
• Ion irradiation significantly changed the structural parameters of the TiN films.
• Annealing of irradiated samples results in full recovery of the destroyed structure.
• Optical constants of implanted titanium nitride samples were increased.

Modification in structural, optical and electrical properties of titanium nitride (TiN) thin films induced by argon ion irradiation and thermal annealings was studied using various experimental techniques. TiN thin films deposited by dc reactive sputtering on Si substrate were implanted with argon ions at 200 keV. As-implanted samples were annealed before or after ion irradiation at 600 °C and 700 °C, respectively. Rutherford backscattering spectrometry, X-ray diffraction, cross-sectional (high-resolution) transmission electron microscopy, spectroscopic ellipsometry and electrical measurements were carried out in order to study structural, optical and electrical properties of TiN/Si samples. After irradiation with 200 keV Ar ions the columnar microstructure of TiN was changed and the presence of smaller crystalline grains was observed. Partial loss of columnar structure observed in implanted samples was completely recovered after annealing at 700 °C. Observed changes in microstructure induced by ion irradiation and annealings were correlated with the variation in optical parameters obtained by spectroscopic ellipsometry. It was found that both refractive index and extinction coefficient are strongly dependent on the defects' concentration and size of the crystalline grains in TiN layers.