THERMALLY ACTIVATED INTERFACE SHIFT IN THE TUNGSTEN SILICON MULTILAYERS/

The in situ x-ray reflectivity measurements during linear and isotherm al annealings of a W/Si multilayer (ML) were performed, and successive disappearance and reappearance of the second and third ML Bragg maxim a between 400 and 500 degrees C were observed. Such behavior is direct evidence of a long-range interface shift, and was found to be connect ed with a substantial decrease of the electronic density of the expand ing originally W layers and the ML period. Surprisingly, the changes t ake place without smearing-out the interfaces. The results are explain ed by the Si diffusion into the W layers. (C) 1996 American Institute of Physics.