LAYER SEQUENCE AND SILICIDE FORMATION OF A CO/(REFRACTORY METAL) BILAYER ON (100)SI SUBSTRATE

The solid state reactions of bilayer systems, such as Co/Cr and Co/V, with a silicon substrate have been investigated. The layer sequence could be explained in terms of competitive relations between the diffusion of cobalt atoms toward the substrate and the surface reaction (i.e., silicide formation at the silicon substrate). It was also found that the intermixing between the cobalt and the refractory beneath it is related to the solid solubility between them, and the layer reversal phenomenon critically depends on the silicide formation temperature of the interlayer refractory metal. For example, in the Co/Cr bilayer, where the silicide formation temperature of the chromium is not higher than that of the cobalt, only a partial layer reversal occurs. However, in the Co/V bilayer, where vanadium has a higher silicide formation temperature than cobalt, a complete layer reversal occurs. (C) 1995 American Institute of Physics.