Crystallographic texture of C54 titanium disilicide as a function of deep submicron structure geometry

Abstract

Detailed analysis of the crystallographic texture of C54 TiSi2 was performed and showed a strong correlation between the geometry of the suicide structures and preferential crystallographic orientation. The study was undertaken on blanket and patterned TiSi2 films formed in the reaction between 32 nm of Ti and undoped polycrystalline silicon using both in situ x-ray diffraction during heating and post-anneal four-circle pole figure reflection geometry measurements. Full pole figures were taken to determine the distribution of C54 TiSi2 grain orientations in narrow (0.2 to 1.1 μm) lines which was compared with similar results obtained from unpatterned (blanket) films. While in blanket films we found the presence of weak 〈311〉 C54 TiSi2 crystallographic orientation perpendicular to the sample surface, the 〈040〉 preferential orientation dominated in patterned submicron line structures and increased with decreasing linewidth. Using pole figure analysis, we observed strong 〈040〉 fiber texture in narrow lines with a slight variation in the tilt of the (040) planes normal in the direction perpendicular to the line (full width at half maximum [FWHM] ≈6°), but very little along the length of the line (FWHM ≈2°). In addition, a preferred in-plane (azimuthal) orientation of 〈040〉 crystals was found which showed that most of the 〈040〉 grains had their (004) plane normals oriented parallel with the line direction. These findings support a model of the C49 to C54 TiSi2 transformation involving rapid growth of certain orientations favored by the one-dimensional geometry imposed by narrow lines.