Current crowding in high-density VLSI metallization structures

Novel metallization schemes for submicrometer device interconnections abound in the continuing quest to increase layout density. As dimensions shrink, the current density flowing in these interconnection lines increases. For this reason, design and fabrication processes must seek to alleviate the possibility of electromigration failure. One factor that affects the electromigration mean time to failure is the degree to which the current flow within a metal conductor is distributed throughout the conductor volume. In this brief, we derive analytical expressions for the current density distribution within a promising new metallization structure. We then examine the uniformity of the current density and discuss the effect of metal resistivity on this current density distribution.