Ti-silicide formation during isochronal annealing followed by in situ ellipsometry

Single-wavelength ellipsometry is employed to monitor in situ the reaction of titanium layers of different thickness (10-80 nm) with Si(100) to form t itanium silicides during heating at constant rates up to 100 K/min. Previou s studies performed on the platinum/silicon system showed that by the use o f 'Kissinger' plots the activation energy for the formation of the intermed iate silicide phase Pt,Si and that of the final PtSi can be determined with an accuracy of 50 meV. Additionally, by directly modelling the evolution o f the ellipsometric data as they were obtained during the temperature ramp the pre-exponential growth factor of the two reactions was determined as we ll. In the present study the reaction of Ti with Si to the intermediate C49 -TiSi2 phase was followed and the activation energy of this reaction was de termined to be 2.30 eV. The isomorphous C49-/C54-TiSi2 phase transition can also be traced by ellipsometry. However, the change in the ellipsometric a ngles is less pronounced which might be ascribed to a TiOx overlayer. Compl ementary to the ellipsometric analysis of the silicidation, the chemical co mposition of the reaction products and the thicknesses of the formed layers were identified at crucial stages of the reaction by X-ray diffraction, Ra man spectroscopy, and Rutherford backscattering spectroscopy. (C) 2001 Else vier Science B.V. All rights reserved.