Atomic layer deposition of TiN films : growth and electrical behavior down to sub-nanometer scale

During the last several decades, titanium nitride (TiN) has gained much interest because of its low resistivity, chemical inertness and compatibility with complementary metal-oxide-semiconductor (CMOS) technology. Thin films of TiN are commonly used as diffusion barrier and gate material for CMOS devices. Mostly sputtering and chemical vapor deposition (CVD) techniques were employed to deposit the TiN films. However, to achieve thin conformal films with accurate thickness control and excellent step coverage, atomic layer deposition (ALD) has become an ideal choice for making such high quality films in the thickness range of a few tens of nanometers. In this work, the growth mechanism and electrical properties of ALD TiN films are investigated. The films are grown on silicon dioxide (SiO2) substrate using titanium chloride (TiCl4) and ammonia (NH3) as precursors in the pressure range of 2.6-3.2 ×10-2 mbar and temperature range of 350−425 oC. The growth of the films is monitored by real time in situ spectroscopic ellipsometry (SE). The films are characterized by other complementary analysis techniques, including atomic force microscopy (AFM), high-resolution scanning/transmission electron microscopy (HR-SEM/TEM), X-ray fluorescence (XRF) and X-ray photoluminescence spectroscopy (XPS). We fabricated test structures to characterize electrical properties of the thin films. The main results of this research are presented in this thesis.