The effect of microrelief evolution on the angular dependence of polycrystalline Cu sputtering yield

Abstract

The dynamically steady-state surface relief of polycrystalline copper sputtered by high-dose (1018–1019ion/cm2) 30keV Ar+ ion bombardment at room temperature has been traced as a function of the ion incidence angle θi in a wide (0–80°) angular range. For each incidence angle the distribution of local slope angles of relief facets f(β) in ion incidence plane and the corresponding distribution of the local angles of incidence w(θ) have been measured using the laser goniophotometry (LGP) technique. It has been found that the distribution f(β) has a narrow peak at grazing ion incidence, two wide peaks at oblique, and three peaks at normal ion incidence. The obtained results are discussed in terms of the theory of surface erosion under ion bombardment. A correction to the angular dependence of the sputtering yield was produced using the OKSANA computer code simulation for a smooth copper surface and the measured distributions w(θ). The experimental data and the calculation results agree well in the angular range θi=0−60°. At θi>60° the experimental points are close to the simulated curve for a smooth surface.