Bimodal Dielectric Breakdown Failure Mechanisms in Cu–SiOC Low- k Interconnect System

The obtained bimodal V_BD failure distribution for Cu/SiOC low-k dielectric is attributed to the two main failure mechanisms that are distinguished by their current-voltage curves and physical failure modes. Type 1 failures show an abrupt increase in leakage current, i.e., an electrical short, without any apparent physical damage. Extrinsic factors such as shorted Cu lines and particle contamination that is already present in between metal lines are believed to be the cause of failure, and this is supported by the temperature independence. On the other hand, Type 2 failure mode follows an intrinsic breakdown mechanism due to its high V_BD, temperature dependence of V_BD, and visible burn marks, indicating thermal breakdown of the dielectrics in the interconnect system.