Ar ions and oxygen plasma interactions of amine terminated organosilicate glass: A combined experimental and ab initio simulations study.

Ar⁺ ion bombardment (900 eV) of organosilicate glass (OSG) in the presence of NH3 (1x10^-6 Torr) yields an overlayer containing Si-NH_x bonds. The NH_x layer decreases the rate of carbon loss from the remaining film upon subsequent oxygen plasma exposure, due to preferential removal of N from the surface region. Ab initio density functional theory calculations have been performed to investigate the stability of the bonds present in low-k dielectrics utilizing a trimethyltrisiloxane model system. Calculated bond energies are 6.30 eV (Si-NH₂), 6.27 eV (Si-OH), 5.69 eV (Si-CH₃), and 5.54 eV (Si-H). The slightly higher calculated Si-NH₂ bond energy is consistent with experiment and indicates that the nitrided OSG surface layer inhibits carbon loss in part by inhibition of O₂ diffusion into the bulk. [ABSTRACT FROM AUTHOR]