Effect of Cracks in TiN Anti-Reflection Coating Layers on Early via Electromigration Failure

Due to the increased circuit current densities and temperatuers, interconnect reliability continues to be one of the major reliability concerns with the progress of device scaling. Electromigration has received extensive study because electromigration failure becomes increasingly serious in multi-level structure, which have been employed to achieve higher interconnect cirucit densities and enhanced functionality. Recently, chemical vapor deposition (CVD) tungsten and chemical mechanical polishing (CMP) have been widely used for good via fill and planarization. However, W-plug vias are more vulnerable to electromigration failure than conventional Al-Al vias. The W/Al interface creates an atomic flux divergence and hinders the continuous supply of Al, hence producing voiding at the interface, leading to eventual failure of the via.