Characterization of C54 titanium silicide thin films by spectroscopy, microscopy and diffraction

Abstract

Titanium silicide (TiSi2) is well known for application as a local interconnect material in complementary metal-oxide semiconductor technology. This paper reports on a comprehensive analysis of titanium silicide thin films by a variety of spectroscopy, diffraction and microscopy techniques. The composition and uniformity of the thin films and the oxygen contamination in the thin films is studied using Auger electron spectroscopy and secondary ion mass spectrometry; these have highlighted the existence of a thin film of uniform and desired composition, with a layer of oxide on the surface. Atomic force microscopy is used to study the surface morphology of the thin films. Microanalysis of the titanium silicide thin films was carried out using cross-sectional transmission electron microscopy; and a silicide–silicon interface which is abrupt and free of amorphous oxide is evident. X-ray diffraction (Bragg-Brentano and glancing angle), reflection high-energy electron diffraction and selected-area electron diffraction have been used to analyse the orientation of the thin films, and verify the presence of the desired C54 phase. The stress of the thin films is qualitatively studied by forming micro-beams of titanium silicide by bulk-micromachining of silicon, and the curvature of the micro-beams formed confirms tensile stress at the silicide–silicon interface. The thin films are also characterized using ellipsometry and thin film resistivity measurements.