Role of temperature on structure and electrical properties of titanium nitride films grown by low pressure plasma enhanced atomic layer deposition

Film crystallinity is one of the key factors determining the resistivity of thin conductive nitride films. In the process of plasma enhanced atomic layer deposition (PEALD), the film crystallinity can be significantly improved by the ion bombardment effect taking place at a low pressure. At a low plasma pressure, ion bombardment supplies additional energy for adatom rearrangement and ligand desorption which significantly enhances the film crystallinity. The deposition of low resistive (∼300 μω cm) TiN films is demonstrated here at a temperature as low as 100 °C. The role of deposition temperature on TiN PEALD structure and electrical properties, such as resistivity and temperature coefficient of resistivity, is investigated. The effect of postdeposition annealing is discussed as well. The resistivity can be further reduced (to ∼60 μω cm) by increasing deposition temperature up to 250 °C or by postdeposition annealing. The increased temperature results in larger grain size, which is the dominant factor in determining the electrical properties of the film.