Correlation Between Bond Cleavage in Parylene N and the Degradation of Its Dielectric Properties

Parylene, a chemical vapor deposited polymer, is shown here to have limited stability when annealed and/or bias temperature stressed. Parylene N thin films were preannealed at 250, 300, and 350 deg C for 30 min and then bias temperature stressed at 150 deg C and 0.5 MV/cm for 0, 30, 60, and 90 min. An order of magnitude increase in leakage current was observed for films preannealed at 300 deg C compared to the 250 deg C films but a precipitous increase was observed for the 350 deg C samples, which lead to shorting. Further, an electron spin resonance signal was observed for films annealed at 350 deg C without bias.