Reliability of dielectric barrier films in copper damascene applications

The film properties of two PECVD deposited dielectric copper barrier films have been optimized to improve BEOL device reliability in terms of electromigration. Two critical aspects that affect electromigration are the dielectric barrier film hermeticity and adhesion to copper. We use a method to quantify the barrier film hermeticity and have optimized the hermeticity of the BLOkappa((TM)) low-kappa dielectric barrier film to be similar to that of silicon nitride. By using FT-IR we find that the film porosity has a much stronger effect than the film stoichiometry on hermeticity. In addition, the interfaces between Damascene Nitride(TM) with copper, as well as BLOkappa with copper have been engineered to improve the interfacial adhesion energy to >10 J/m(2) for both Damascene Nitride and BLOkappa.