Ab initio investigation of interfacial layer formation in the Mo ∕ Si boundary for extreme ultraviolet lithography

The energetics and the electronic structure of the Si ∕ Mo ( 110 ) surface were investigated using the density functional theory calculations in an attempt to clarify the initial stage of silicide layer formation. The energy barriers for the migration of Si adatom to an adjacent hollow site passing the bridge site were calculated to be 0.64 eV [Mo (110)] and 0.74 eV [Si-substituted Mo (110)]. In order to analyze the bonding nature between Si adatom and Mo (110) surface, layer density of states and total valence electron density were obtained. It can be reasonably inferred that Mo 4 d states mainly contributed to the bonding between Mo and Si and, consequently, four Mo-Si covalent bonds were formed around the Si atom at the hollow site.