The surface topography of Ag/Cu alloys sputtered by bombardment with 35–100-keV argon ions

Abstract

The surface topography of two phase Ag/Cu alloys was studied after argon ion bombardment. The parameters investigated include ion beam energy (35–100 keV), dose (1017–1019 ions cm−2) and alloy composition (20, 40, and 50 at. % Ag). At the lower doses the topography revealed the microstructure of the alloy due to higher sputtering rate of the silver crystallites in the eutectic mix of copper and silver crystallites. At intermediate doses the topography reflected the tendency of surfaces to rotate the angle for maximum sputtering yield, and sharp ridges were formed. At the highest dose a dense forest of cones was formed in the eutectic mix regions. The variation of cone angle and height with ion energy was found to be in agreement with previous measurements and theoretical predictions. All the topographic features that have been observed on pure copper were observed on the copper grains which were standing proud of eutectic mix. Rounding of the cone tip and deformation of the cones were observed. It is proposed that this resulted from minimumization of surface energy by diffusion and plastic deformation.