Generation of Bonding Structure Due to Organic Carbon and Organometallic Carbon as a Function of Gas Source

SiOC films with low dielectric properties were deposited by high density plasma chemical vapor deposition (CVD) using mixed source gases by considering of oxygen and bistrimethylsilylmethane. SiOC films can be divided into two bonding structures on the basis of the chemical shift according to the flow rate ratio: the cross-link and cross-link breakage structure. The chemical shift is determined as the result of the Diels–Alder reaction between a carbocation and a substituent group induced by both the resonance and inductive effects during the nucleophilic deposition reaction. The relative carbon content decreases as the oxygen flow rate increases, but the lowest dielectric constant of 2.1 was obtained for an annealed film with an organometallic carbon structure. The different bonding structures between organic carbon due to the dominant resonance and organometallic carbon due to the dominant inductive effect can be analyzed from FTIR and Raman spectra.