Bulk electromigration reliability tests of large-grained aluminum lines with regard to semiconductor contacts

Abstract A test structure was devised for investigating electromigration reliability. Considering electromigration threshold, narrow large-grained Al/Si interconnect lines failed on contacts due to homogeneous bulk electromigration. Failure times were dependent on the uniformity of the contact interfaces. Bulk electromigration was marked by an extremely low mass flow at the test temperature of 200°C. This mass flow will be reduced considerably with decreasing temperature due to the activation energy of 1.38 eV. Si electromigration can damage pn -junctions. A double layer metalization, like annealed Ti-Al, may delay or prevent Si mass flow, but a strong interface electromigration occurs. Comparable double layers are improper for future integrated circuits. The advantage of bulk electromigration is not restricted to narrow lines. Wide lines have to be divided into separated sections, which behave like narrow, large-grained lines.