Codeposited silicides in very-large-scale integration

Abstract

Recently, with a view to their application as gate and interconnection metallization in metal/oxide/semiconductor devices, silicides have been formed by codepositing a metal and silicon mixture in the desired composition followed by annealing at higher temperatures. In this paper the codeposition of silicide films is reviewed. Both refractory and group VIII metal silicides have been deposited in this manner. Co-sputtering from two elemental targets for research purposes, and from one sintered target for routine depositions, are the preferred methods. Unannealed as-deposited films are conducting, and they crystallize on annealing to form lower resistivity silicides. The resistivity depends on the silicon-to-metal ratio and the contaminants. Other properties and processing factors are also discussed. The possible existence of a range of homogeneity in the refractory silicides, but not in group VIII metal silicides, is suggested.