Plasma enhanced chemical vapor deposition of low dielectric constant SiOC(–H) films using MTES/O2 precursor

Low dielectric constant SiOC(–H) thin films were deposited by plasma enhanced chemical vapor deposition (PECVD) using methyltriethoxysilane (MTES) and oxygen as precursors. The SiOC(–H) films were prepared with MTES/O2 flow rate ratio of 80%, rf power of 700 W and the working pressure was varied from 110 to 150 mTorr. Then the films were annealed at different temperatures in an Ar ambient for 30 min in order to study their thermal stability. Film thickness and refractive index were measured by SEM and ellipsometry, respectively. Bonding characteristics of the films were investigated by Fourier transform infrared (FTIR) spectroscopy. The dielectric constant of SiOC(–H) film was evaluated by C–V measurements using Al/SiOC(–H)/p-Si structure. The dielectric constants as low as 2.4 have been obtained for the film annealed at 500 °C with the working pressure of 150 mTorr. The annealing treatment was found to reduce dielectric constant significantly due to abundant incorporation of methyl group into the Si–O network. These results demonstrated the promising characteristics of SiOC(–H) thin films deposited by using oxygen and MTES precursor.