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 various times. The reactivity and the reaction-product morphology were characterized using optical microscopy, surface profilometry, X-ray diffraction, 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 reaction proceeded, the initially formed Ni3Si2 layer was converted to Ni2Si and carbon precipitates were observed within this zone. The thin nickel film reacted completely with SiC after annealing at 950 degrees C for 2 h. The thermodynamically stable Ni2Si is the only observed silicide in the reaction zone up to 1050 degrees C. Above 1250 degrees C, carbon precipitated preferentially on the outer surface of the reaction zone and crystallized as graphite. The relative adhesive strength of the reaction layers was qualitatively compared using the scratch test method. At temperatures between 850 to 1050 degrees C the relatively higher critical load values of 20-33 N for SiC/Ni couples are formed.