Effect of current crowding on copper dual damascene via bottom failure for ULSI applications

Reliability issues are becoming more important in interconnect via. Electromigration experiments are performed on line/via structures in a two level Cu dual damascene interconnection system and it is found that wide line/via fails earlier than the narrow line/via. Semi-classical width dependence Black's equation together with finite element analysis revealed that the difference in the time to failure is due to the much larger average current density along the heterogeneous interface for the wide line/via structure, and good agreement is obtained between the simulation and experimental results.