Reduced aluminium electromigration in future integrated circuits — A problem of test procedure and threshold mechanisms

Abstract

In aluminium interconnect lines of integrated circuits there are different electromigration failure modes such as stripe interruptions and contact failures. For the conditions demonstrated here, the electromigration drift velocity limits the lifetime of metallization by contact failure long before interruptions would occur. In short aluminium lines, as well as in all Al-Cu lines, the mass flow is reduced by a grain boundary electromigration threshold. Considering different threshold mechanisms, grain boundary and interface electromigration can be eliminated in large-grained narrow lines. The remaining, drastically reduced bulk electromigration will not be detectable under operating conditions.