Investigation of Boron Redistribution during Silicidation in TiSi(2) using Atom Probe Tomography

The silicidation reaction between a titanium metal film, capped by a TiN layer, and a boron-implanted silicon substrate has been analyzed by Atom Probe Tomography. Two different thicknesses of titanium metal film were considered to study the process of silicidation and subsequent effects on the redistribution of the dopants. The concentration depth profiles determined by atom probe tomography and secondary ion mass spectrometry depict an additional amorphous TiSi(x) phase for the thicker Ti film in contrast to a fully silicided TiSi(2) layer for the thin one. The experimental data shows lower solubility of boron in TiSi(2) in comparison to the amorphous TiSi(x) phase. Additionally, boron accumulation at the interface between the TiSi(2) and the TiN capping layer is observed. The atom probe study clearly reveals boron precipitates at interfaces between TiSi(2) and Si substrate or TiN capping layer. These precipitates can be identified either to a stoichiometric ratio of TiB(2) or TiB correlated to the size of the individual precipitate.