Structural and dielectric properties of parylene-VT4 thin films

•Parylene-VT4 exhibits a low dielectric constants and high thermal stability.•Parylene-VT4 shows structure stability (b-hexagonal) after FH aromatic substitution.•Parylene-VT4 shows a dielectric constant values, in the range of 2.05–2.35.•Annealing effect improves the dielectric properties of the parylene-VT4.•Material for microelectronic applications as organic insulator integrated layer.

58% semi-crystalline thin parylene-VT4 (–H2C–C6F4–CH2−)n films, have been investigated by dielectric spectroscopy for temperature and frequency ranges of [−120 to 380 °C] and [0.1–105 Hz] respectively. The study comprises a detailed investigation of the dielectric constant, dielectric loss and AC conductivity of this fluoropolymer. Dielectric behavior of parylene-VT4 is represented by a low dielectric constant with values in the range of 2.05–2.35 while the dielectric losses indicate the presence of two relaxation processes. Maxwell−Wagner−Sillars (MWS) polarization at the amorphous/crystalline interfaces with activation energy of 1.6 eV is due to the oligomer orientation. Electrical conductivity obeys to the well-known Jonscher law. The plateau in the low frequency part of this conductivity is temperature-dependent and follows an Arrhenius behavior with activation energy of 1.17 eV (deep traps) due to the fluorine diffusion. Due to its thermal stability with a high decomposition temperature (around 400 °C under air and 510 °C under nitrogen) and due to its good resistivity at low frequency (1015–1017 Ω m−1), parylene-VT4 constitutes a very attractive polymer for microelectronic applications as low k dielectric. Moreover, when parylene-VT4 is subjected to an annealing, the dielectric properties can be still more improved.

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