RAMAN-STUDY OF TUNGSTEN DISILICIDE FORMATION IN THIN-FILMS

The formation of WSi2 by thermal annealing of W/Si multilayers on Si s ubstrate and of W thin films on Si0.67Ge0.33 has been characterized by Raman scattering. Frequency shifts of these lines give evidence of te nsile stresses in the films. Intensity measurements of the Si substrat e line in different samples have allowed an estimation of the absorpti on coefficients of WSi2 and of W respectively close to 710(5) cm(-1) and 3.510(7) cm(-1). After annealing, the WSi2 lines are observed sim ultaneously with slight frequency shifts of the Si-Ge lines which agre e with a Ge concentration increase of the alloy. An enriched-Ge compos ition is also evidenced in the X-ray diffraction pattern of the sample s in addition to the initial composition. Attempts of laser annealing on the same as-deposited W films on Si-Ge reveal a considerable and ir reversible intensity increase of the Ge-Ge lines attesting a Ge-enrich ment of the alloy as a result of the laser heating as well as the form ation of additional lines in the spectrum.