TUNGSTEN SILICIDE FORMATION BY XECL EXCIMER-LASER IRRADIATION OF W SISAMPLES/

We report a study of the formation of tungsten silicide at the W-Si in terface, induced by multipulse (up to 300 shots) XeCl excimer-laser ir radiation of W(150 nm)/Si and W(500 nm)/Si samples. Laser fluences ran ging from 0.6 to 1.8 J/cm2 were used. After laser treatment the sample s were examined by different diagnostic techniques: Rutherford backsca ttering spectrometry, X-ray scattering, resistometry, and surface prof ilometry. Numerical computations of the evolution and depth profiles o f the temperature in the samples as a consequence of a single 30 ns la ser pulse were performed as well. The results indicate that it is poss ible to obtain a tungsten silicide layer at the W-Si interface at quit e low fluences. The layer thickness increases with the number of laser pulses. Complete reaction of the 150 nm thick W film with silicon was obtained at the fluence of 1.2 J/cm2 between 30 and 100 laser pulses and at 1.5 J/cm2 after 30 laser pulses. The sheet resistance of these silicides was 5-10 OMEGA. At the used fluences for the 500 nm thick W film only the onset of silicide synthesis at the W-Si interface was ob served.