Molecular dynamics simulation of Cu and Ar ion sputtering of Cu (111) surfaces

Abstract

In ionized physical vapor deposition, used in Cu interconnect technology, the interaction of energetic ions with the growing Cu film is sensitive to both the impact angle and the energy. Detailed information, such as the angle and energy dependence of the sputter yield and sticking probability, is required for realistic feature scale modeling of film coverage in the metallization of micron-sized features (vias and trenches) in integrated circuits. Here we describe the results of molecular dynamics (MD) simulations of sputtering of Cu (111) surfaces by Cu and Ar ions suitable for incorporation into feature scale simulations. For each impact angle and energy considered (10–100 eV for Cu ions and 50–250 eV for Ar ions), the following averaged properties were calculated: sputter yield (number of Cu atoms sputtered per impact), sticking probability, thermal accommodation coefficient, average reflection angle of the impact ion, and average emission angle of the sputter products. The calculated sputter yields and energy threshold at normal incidence for both Ar and Cu sputtering of Cu are in good agreement with experiment and other MD simulations. Detailed comparisons are also made with previously reported sputter yields calculated with binary collision theory.