Direct observation of a critical length effect in dual-damascene Cu/oxide interconnects

Electromigration results have provided clear evidence of a short or "Blech" length effect in dual- damascene, Cu/oxide, multilinked interconnects. The test structure incorporates a repeated chain of Blech-type line elements and is amenable to failure analysis tools such as focused ion beam imaging. This large interconnect ensemble provides a statistical representation of electromigrationinduced damage in the regime where steady-state interconnect stress is manifest. Statistical analysis yields a critical length of 90 mum for interconnects with line width 0.5 mum at j=1.0x10(6) A/cm(2) and T=325 degreesC. (C) 2001 American Institute of Physics.