Effect of Grain Boundary/Interface Network on Damaging Mechanism due to Atom Migration Induced by Electric Current and Stress in an LSI Conductor

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The electric current induces atom transport in an LSI conductor and the "electromigration (EM)" along grain boundary/interface (GB/IF) often brings about a cavity. Since the EM, of which flux is proportional to the electric current density, does not satisfy the law of mass conservation, stress is generated along the GB/IF.In other words, the migration due to the stress, "stress migration (SM)", compensates the mass conservation. Thus, the atoms flow not only by the EM but also by the SM under the condition without external loading. In this study, the functional of atom flux due to the EM/SM is derived and a numerical simulation method of migration along a GB/IF network is proposed. The mechanism of cavity growth in a polycrystalline LSI conductor under an electrical current is investigated on the basis of numerical simulation. The SM transports the atoms into the GB through the cavity tip and they are moved away by the EM.The cavity growth rate is strongly influenced by the IF/GB network.