The thermal stability of tungsten/silicon multilayered nanostructures

The influence of excimer laser processing on the thermal stability, especially 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=1 or 100 pulses. Then, they were studied by atomic force microscopy, thus completing previous X-ray scattering analyses. It was found that for x≥0.5 the clusters are formed at the MLs surface even in the as-deposited state. Sources of surface roughness are the laser melting itself, Si crystallization and shrinking of the volume connected with the formation of tungsten silicides.