INFLUENCE OF OXYGEN ON THE FORMATION OF REFRACTORY-METAL SILICIDES

In very-large-scale integration, refractory metal silicides are generally obtained by codeposition but there is increased interest in self-aligned structures where the formation of the silicide occurs through a reaction between the deposited metal and silicon. The presence of impurities may affect the formation process and the properties of the silicide films. On the basis of thermodynamic and kinetic considerations it is possible to establish some essential features of the influence of oxygen as a function of the amount of oxygen and its location, the silicide considered and the procedure used to obtain it. Experimental evidence is presented to illustrate the behavior of oxygen in various systems. Methods to eliminate oxygen contamination or to overcome its detrimental effects are discussed.