Influence of oxygen plasma treatment on boron carbon nitride film composition

Variations in the composition and bonds of boron carbon nitride (BCN) film caused due to an oxygen (O2) plasma ashing process are investigated for a low dielectric constant (low-k) insulating film for next generation LSI devices. The O2 plasma treatment is preformed for BCN samples with various C compositions. The etching rate of BCN films with an O2 plasma decreases with increasing C composition. The reaction of O atoms is suppressed in the BCN film with a high C composition. B-N and B-C bonds with lower bond energies are easily broken by the O2 plasma and replaced by the generation of B-O, N-O, and C-O bonds. The B-atom concentration for all samples is decreased significantly by the O2 plasma treatment. Ion bombardment may play a more dominant role than the O-atom reaction in the etching of the BCN film. The existence of C-N bonds with a high bonding energy may suppress etching and incorporation of O atoms.