Structural and dielectric study of parylene C thin films

alpha, beta, and gamma relaxation mechanisms have been identified in semicrystalline (45% of crystallinity) parylene-C (-H2C-C6H3Cl-CH2-)(n) films. C-Cl bonds induce the beta-relaxation and explain increase in the dielectric constant as the frequency decreases in usual temperatures of operation for devices incorporating parylene-C. At cryogenic temperature (<-20 degrees C), gamma-relaxation is assigned to the local motions of phenyl groups. Both beta and gamma relaxation processes obey an Arrhenius law with activation energy E-a(beta)=91.7 kJ/mole and E-a(gamma)=8.68 kJ/mole. alpha-relaxation associated with cooperative segmental motions of the (-H2C-subset of-CH2-)(n) chains is observed with a peak at 10(-2) Hz for T=80 degrees C and follows a Vogel-Fulcher-Tamman-Hesse law.