RAMAN-STUDY OF THE FORMATION OF TUNGSTEN SILICIDE THIN-FILMS

Raman scattering has been used to study the formation of tungsten sili cide thin films. The tungsten films were sputter deposited on p-type [ 100] and [111] silicon substrates and the tungsten silicide formed by either rapid thermal annealing or laser annealing. Raman data were cor related with sheet resistance measurements and scanning electron micro graphs to demonstrate that rapid thermal annealing at high temperature s for short times results in low resistance tungsten silicide thin fil ms. All of the annealed samples forming tetragonal tungsten silicide d isplay a sharp Raman peak around 333 cm-1 and a less intense peak arou nd 450 cm-1. X-ray diffraction studies confirmed the formation of tetr agonal tungsten silicide. Samples laser annealed at low laser powers s how additional Raman peaks which suggest the formation of an intermedi ate WSi(x) state. Finally, an estimate of the microcrystallite size of the tungsten silicide thin films was obtained from the Raman data for both rapid thermally annealed and laser annealed samples.