Dielectric properties of parylene AF4 as low-k material for microelectronic applications

Using dielectric spectroscopy analysis, three relaxation mechanisms have been identified in 60% semi-crystalline parylene AF4 ([-F2C-C6H4-CF2-]n) fluoropolymers. At high temperature, fluorine species located at the electrode/polymer interface involve a space-charge polarization. β-Process assigned to local molecular motions of the C-F dipoles and the γ-relaxation due to local fluctuations of the F2C-C6H4 groups are also evidenced at intermediate and cryogenic temperatures respectively. Space-charge fluorine F−, β and γ relaxations obey an Arrhenius law against temperature with activation energy Ea (F−) = 1.26 eV, Ea (β) = 0.59 eV and Ea (γ) = 0.29 eV.