Recently, it has been suggested that the existence of certain oxygen-containing chemical groups at copper/polymer interfaces aids copper ionization and its subsequent diffusion into these polymers. In the present study, poly(paraxylylene-N) or Parylene-N was selected for copper diffusion studies. It was demonstrated that no copper ion penetration was detected in the Parylene-N films under bias temperature stressing conditions of 150degreesC and 0.5 MV/cm. The present finding suggests that one may control copper penetration by employing dielectrics or passivation layers devoid of oxygen in the multilevel interconnect metallization scheme. (C) 2003 The Electrochemical Society.