Asymmetrical critical current density and its influence on electromigration of two-level W-plug interconnection

Electromigration failure at contacts and vias is the potential limitation o f interconnect reliability in multilevel structures. In two-level structure s, it has been found that the upper and lower metal levels exhibit differen t electromigration failure characteristics; the latter fails predominantly. In this work, we have systematically studied the critical current densitie s: of the lower and upper level conductors terminated at W-plug vias. We fo und that the critical current density for the upper level is significantly higher. The effect of passivation layer on the critical current density is discussed. (C) 2000 The Electrochemical Society. S0013-3651(99)12-060-3. Al l rights reserved.