Growth of Ti and TiSi2 films on Si(111) by low energy Ti+ beam deposition

The deposition of titanium and titanium disilicide thin films on Si(111) by low-energy (10–500 eV) Ti+ beams in the temperature range 25–700°C has been investigated by in-situ Auger electron spectroscopy (AES) and reflection high-energy electron diffraction (RHEED) as well as ex-situ depth profile X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and transmission electron diffraction (TED). Small XPS chemical shifts in the Si2p and Ti2p peaks and changes in the AES line shapes originating from elemental silicon and titanium and the titanium disilicide compound have been resolved. The XPS shifts were used for resolution of the silicide layer in the depth profiles. This interfacial silicide layer is formed even at 25°C, and its characteristics are dependent on both Ti+ energy and Si temperature. The RHEED and TED results confirm the growth of a polycrystalline Ti film for T≤500°C, the C49–TiSi2 phase for T∼600°C, the C54–TiSi2 phase for T∼700°C or above, and the existence of synergistic effects between the substrate temperature and Ti+ kinetic energy on the crystalline quality of the films. The AFM images exhibit a broad range of morphologies as a function of growth conditions. The effects of energetic ions and temperature in Ti and TiSi2 film deposition are discussed accordingly.