Electromigration threshold in single-damascene copper interconnects with SiO/sub 2/ dielectrics

We demonstrate the electromigration threshold, or the so-called short-length effect, in single-damascene copper interconnects with SiO/sub 2/ dielectrics. With standard electrical lifetime measurements and a simplified equation based on the Blech model, the length-dependent electromigration behavior is studied quantitatively over a temperature range between 295/spl deg/C and 400/spl deg/C. It is shown that the electromigration threshold becomes more prominent with decreasing temperature. The applicability of the proposed equation is justified, and the practical aspects of the electromigration threshold in copper technologies are discussed.