Multiparameter investigation of the sputtering behavior of Ag∕Cu Alloys for low energy argon ion bombardment

Abstract

The sputtering behavior of Ag∕Cu alloys due to low energy (100–1500eV) Ar+ bombardment as a function of component composition, sample temperature, ion current density, ion dose, and ion energy has been completed. The results indicate that the surface topography development is a strong function of temperature and depends to a lesser extent on ion energy, ion dose, and ion current density. The surface at low temperature coupled with low ion dose and/or low ion current density is flat and faceted with widely dispersed large cones. As the temperature is raised, the rate of Ag surface diffusion increases faster than that of Cu and Ag begins to coat the Cu grains thereby, decreasing the subsequent erosion of the Cu. Selective sputtering of the higher yield Ag and continuous Ag diffusion toward the surface results in a decrease in the Ag concentration in the near surface region as measured by energy dispersive spectroscopy. Auger electron spectroscopy (AES) depth profiles indicate significant diffusion of both Cu and Ag when the electron beam was used in spot mode. Angular distributions of sputtered material indicate that Ag is ejected more preferentially at large angles to the surface normal. The total sputter yield is a function of temperature, ion energy, and dose. These effects are related to the growth of surface topography and the subsequent recapture of ejected material on to the sides of surface features. A method of increasing the thermal conductivity between the sample and holder using graphite colloid was found to affect the surface topography growth and AES profiles. The results of these experiments have implications for depth profiling of multicomponent metallic alloys.