Dielectric relaxation spectroscopy of single- and double-layer polyimide/SiO2 thin films

High temperature dielectric relaxation spectroscopy (DRS) experiments have been performed on MIS (metal-insulator-semiconductor), MOS (metal-oxide-semiconductor) single-layer and MIOS (metal-insulator-oxide-semiconductor) double-layer structures, where I is polyimide (PI) film (10μm), and O is PECVD SiO₂ thin film (1.5 μm-thick), from 200 to 350 °C, in the 10^-1 Hz to 10⁶ Hz frequency range. In such a high temperature range and/or at low frequencies, the dielectric spectra are often influenced by interfacial dielectric relaxations such as Maxwell-Wagner-Sillars (MWS) and electrode polarization (EP). The empirical Havriliak-Negami (H-N) model is used to determine the σ_dc values from the effective ac dielectric response. For single-(PI) and double-layer structures (PI/SiO₂), the σ_dc varies from 1.1×10^-10 to 5.5×10^-9 Ω^-1 cm^-1 and from 7×10^-14 to 2.3×10^-12 Ω^-1 1cm^-1 between 250 and 350°C, with an activation energy of the conduction phenomenon of 1.1 and 0.95 eV, respectively. The PI/SiO₂ structure is suited for semiconductor device passivation applications at high temperature up to 300°C.