Characterization of barrier and seed layer integrity for copper interconnects

A matrix of characterization techniques is presented, aiming at a thorough investigation of novel barrier / seed films with respect to their applicability in Cu damascene interconnects. The paper primarily focuses on the reliable testing of the Cu diffusion barrier performance using bias temperature stress (BTS) and triangular voltage sweep (TVS), as well as on the testing of Cu-wetting with regard to electromigration (EM), and on direct Cu plating. Typical test procedures are described. A good adhesion to low-k dielectrics, a good oxygen diffusion barrier performance and chemical mechanical polishing (CMP) capability are identified as further important criteria.