INFLUENCE OF SURFACE CARBON ON THE FORMATION OF SILICON-REFRACTORY METAL INTERFACES

The influence of different chemical forms of carbon on the character o f processes taking place at Si-metal interfaces was shown. Carbon in t he form of a surface carbide of W (or Re and Mo) in contact with silic on is expelled from the surface to the bulk of the metal, to form a so lid solution, causing cleaning of the interface. Carbon in the form of a monolayer graphite film (on Ir or Re) at T<600 K is impermeable to the adsorption of silicon atoms, assuming the formation and maintenanc e of a sharp, non-reactive interface. The same form of carbon at T>900 K, on the contrary, is completely permeable to silicon and does not i nfluence silicide formation. Heating the silicon and rhenium interface which contains carbon dissolved in the metal bulk to T>1200 K leads t o its fast precipitation on the interface, in the form of a monolayer graphite film. The same amount of carbon, depending on the sample preh istory, can appear in different chemical forms and influence the inter face processes in opposite ways.