Adsorption of hydrocarbon components generated in deuterated benzene plasma studied by in situ real-time infrared absorption spectroscopy

In situ, real-time infrared absorption spectroscopy in the multiple internal reflection geometry was employed to investigate the evolution of hydrocarbon components deposited during plasma-enhanced chemical vapor deposition with a deuterated benzene source. We detected a peak attributed to the C-D stretching vibration of the deuterated phenyl group, which indicated a mode in which the benzene ring structure is retained on the substrate during the adsorption. The evolution of each peak during the plasma exposure suggests that the addition reaction occurs during the adsorption. Furthermore, we observed that with increasing substrate bias applied, the benzene ring structures in the film were disrupted and the amount of alkane components increased. This addition reaction proceeded on the film surface, regardless of the substrate bias.