Preparation and properties of low-dielectric-constant SiOC(-H) thin films deposited by using PECVD

Low-dielectric-constant SiOC(-H) films were deposited on p-type Si(100) substrates by using plasma enhanced chemical vapor deposition (PECVD) with methyltriethoxysilane (MTES) and oxygen gas as the precursors. The SiOC(-H) films were deposited at various substrate temperatures while all the other experimental parameters were kept constant. The SiOC(-H) film's properties, such as the deposition rate, refractive index, thickness, current-voltage (C-V) characteristics and the dielectric constant, were evaluated. The deposition rate decreased with increasing substrate temperature. The activation energies of the SiOC(-H) films were found to be -0.036 and -0.021 eV, for lower substrate temperature (RT - 200 °C) and higher substrate temperature (beyond 200 °C), respectively. When the substrate temperature was increased, the precursor molecules dissociated completely due to a breaking of the cage structures (voids), resulting in the formation of denser SiOC(-H) films. The dielectric constant of the SiOC(-H) film increased from 2.53 to 2.96 with increasing substrate temperature from RT to 350 °C.