Permittivity and Conductivity of Low-Dielectric-Constant SiOC:H Films Deposited by Plasma-Enhanced Chemical Vapor Deposition

We study the dielectric properties (dielectric constant, loss and leakage current) of SiOC:H (silicon oxycarbide) thin films deposited by plasma-enhanced chemical vapor deposition from trimethylsilane (Dow Corning Z3MS gas precursor). The complex permittivity is studied from 0.01 Hz to 1 MHz as a function of temperature (room temperature to 115°C). The conductivity is studied as a function of the electric field, temperature, and time (current transients following application of bias). The films possess a low dielectric constant (around 2.8), which slightly decreases (from 2.88 to 2.82) when the frequency increases from 0.01 Hz to 1 MHz. The temperature dependence of the dielectric constant follows a Debye law (variation with Electronic, ionic, and dipolar polarizations contribute 0.93, 0.53, and 0.37 to the dielectric constant, respectively. The loss factor is around 0.006 (dissipation factor Application of a voltage step leads to current decays which persist up to at least The current density is very low in these films (a few at 1 MV/cm). Leakage currents are thermally activated (activation energy of 0.35 eV).