Deposition and characterization of low-dielectric-constant SiOC(-H) thin films for interlayer dielectrics in multilevel interconnections

The SiOC(-H) films were deposited on p-type Si(100) substrates by using UV-source-assisted plasma-enhanced chemical-vapor deposition from methyltrimethoxysilane (MTMS) and oxygen precursors. The bonding configuration and the chemical structures of the SiOC(-H) films were investigated by using Fourier-transform infrared spectroscopy in the absorbance mode. UV irradiation of the MTMS+Ar+O-2 bulk plasma enhanced the selective dissociation of precursor molecules, leading to good film formation. At the same time, the carbon content increased about 2 % for the film deposited with UV irradiation compared to the film deposited without UV irradiation. The dielectric constant of the SiOC(-H) film deposited with UV irradiation decreased compared to that of the film deposited without UV. The lowest dielectric constant, about 2.13, was obtained for the SiOC(-H) film deposited with UV irradiation and annealed at 400 degrees C with a MTMS/O-2 flow rate ratio of 80 % at an rf power of 500 W.