The thermal stability of tungsten/silicon multilayered nanostructures

The influence of excimer laser processing on the thermal stability, especia lly on the surface roughness evolution of W1-xSix/Si multilayers (MLs), is studied. MLs with the compositions x = 0 (W/Si) and x = 0.33, 0.5 and 0.66 were evaporated by e-beam evaporation and co-evaporation onto Si substrates . The samples were irradiated by XeCl laser pulses at fluences F = 0.075-0. 6 J cm(-2) and N = I or 100 pulses. Then, they were studied by atomic force microscopy, thus completing previous X-ray scattering analyses. It was fou nd that for x greater than or equal to 0.5 the clusters are formed at the M Ls surface even in the as-deposited state. Sources of surface roughness are the laser melting itself, Si crystallization and shrinking of the volume c onnected with the formation of tungsten silicides. (C) 2001 Elsevier Scienc e B.V. All rights reserved.