In-situ monitoring of the electronic properties and growth evolution of TiN films

We implemented in-situ spectroscopic ellipsometry (SE) to monitor the evolution of microstructure, composition and electronic properties of TiNx (1≤x≤1.12) films, 0.5–50 nm thick, during their growth. Effective medium theories described the growing films in terms of their constituent materials and provided the evolution of the film composition. The SE results revealed the growth mechanism, which can be either the island or layer-by-layer growth mode, depending on the substrate/film lattice match and the ion irradiation conditions. The TiN island growth is a two-step process based on the growth of a defective TiNx layer before the development of the TiN film. The evolution of the films’ electronic properties can be also evaluated by SE; thus, we controlled the evolution of carrier density and film resistivity and we identified the low thickness limit for stable, conducting TiN layers.