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 degreesC for 30 min and then bias temperature stressed at 150 degreesC 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 degreesC compared to the 250 degreesC films but a precipitous increase was observed for the 350 degreesC samples, which lead to shorting. Further, an electron spin resonance signal was observed for films annealed at 350 degreesC without bias. (C) 2004 The Electrochemical Society.