Limitations of TiSi2 as a source for dopant diffusion

The application of TiSi2 as a dopant diffusion source for boron and arsenic was studied. The TiSi2 layers were formed by the usual salicide process and doped by ion implantation. Diffusion was carried out by various furnace and rapid thermal processing steps. Using secondary ion mass spectrometry, scanning electron microscopy, and x-ray diffraction, clear evidence for compound formation between Ti and the two dopant species is found. This leads to low dopant concentrations at the silicide/silicon interface, very poor efficiency of the diffusion source, and unacceptably high contact resistivities.