INTERFACIAL REACTION AND ADHESION BETWEEN SIC AND THIN SPUTTERED NICKEL FILMS

Thin sputtered nickel films grown on SiC were annealed in an Ar/4 vol% H-2 atmosphere at temperatures between 550 to 1450 degrees C for vari ous times. The reactivity and the reaction-product morphology were cha racterized using optical microscopy, surface profilometry, X-ray diffr action, scanning electron microscopy and electron probe microanalysis. The reaction with the formation of silicides and carbon was observed to first occur above 650 degrees C. Above 750 degrees C, as the reacti on proceeded, the initially formed Ni3Si2 layer was converted to Ni2Si and carbon precipitates were observed within this zone. The thin nick el film reacted completely with SiC after annealing at 950 degrees C f or 2 h. The thermodynamically stable Ni2Si is the only observed silici de in the reaction zone up to 1050 degrees C. Above 1250 degrees C, ca rbon precipitated preferentially on the outer surface of the reaction zone and crystallized as graphite. The relative adhesive strength of t he reaction layers was qualitatively compared using the scratch test m ethod. At temperatures between 850 to 1050 degrees C the relatively hi gher critical load values of 20-33 N for SiC/Ni couples are formed.