Atomistic mechanisms of Cu CMP in aqueous H2O2: Molecular dynamics simulations using ReaxFF reactive force field

Molecular dynamics simulations using ReaxFF reactive force field are employed to study the process of the silica abrasive particle sliding on the Cu(1 0 0) substrate in the aqueous H2O2 in order to clarify the atomistic mechanisms of the Cu chemical mechanical polishing process. Results reveal that there are mainly Cu-H2O, OH-Cu-OH, Cu-OH-Cu, Cu-OH-H2O, O-Cu-OH etc on the substrate, among them, the number of Cu-H2O is the most. And a part of H2O and OH in the above product come from H2O, some from H2O2, and the other are from the recombination of these two types molecule. Under the mechanical sliding effects, Cu atoms are mainly removed in the form of clusters by fracturing of Cu-Cu bonds and Cu-O bonds on the Cu substrate. When the polishing pressure is different, the more Cu atoms are removed, the greater the friction force between the abrasive particles and the substrate and the more H2O molecules are decomposed as the polishing pressure increases. Besides, H2O plays a dual effect by oxidizing the Cu substrate surface as well as by the effect of lubrication. Our results may shed light on the removal mechanism of Cu atoms in the CMP process at the atomic level and help to further understand the CMP of Cu.