Dependence of crystallographic texture of C54 TiSi₂ on thickness and linewidth in submicron CMOS structures

Abstract

Preferential crystal orientation of low-resistance C54 TiSi2 formed in the reaction of polycrystalline and single crystal silicon with titanium was investigated for Ti thicknesses ranging from 15 to 44 nm. Using in situ synchrotron x-ray diffraction during heating of 15 nm of Ti on single crystal Si, we observed that the C54 TiSi2 silicide film showed predominantly 〈040〉 grains oriented normal to the sample. In thicker silicide films the 〈311〉 orientation dominated or film was randomly oriented. An ex situ four circle diffractometer was used to investigate the strong 〈040〉 texture in narrow line arrays of C54-TiSi2 formed on polycrystalline silicon with linewidths from 0.2 to 1.1 μm. We observed that the angular distribution of 〈040〉 TiSi2 grains is dependent on the line direction, where the majority of grains had their (100) planes 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.