Investigation of Boron Redistribution during Silicidation in TiSi_2 using Atom Probe Tomography

摘要

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.