Blech effect in single-inlaid Cu interconnects

Abstract

This work demonstrates that we can prevent. electromigration failures in single-inlaid copper during DC electromigration testing by taking advantage of the Blech effect. Electromigration tests were performed on singleinlaid copper metal lines ranging from 5 to 250 pm in length at 300°C and a stress current density of 1 . 4~1 0~ Ncm'. Shorter lines showed no resistance increase, while longer lines failed at the same time, independent of line length. The critical product (jl), was calculated to be between 2800 and 3500 Ncm at 300°C for single-inlaid copper.

Temperature scaling of electromigration threshold product in Cu/low-K interconnects

“…Smaller number of experiments at 260 and 330°C leads to larger error bars at these temperatures. Even though, (jL) c values are in good agreement with previously published results [2,3,5]. It is worth noting that no failure could be detected for EM experiments performed at a jL value lower than (jL) c , independently of metal length and current density for a given temperature.…”

“…The threshold product value depends on the interconnect mechanical properties and is usually determined through accelerated life tests at a temperature far above the product operating temperature. However, it is still not clear from previous works whether (jL) c is temperature dependent [2,3,4] or not [5,6,7]. An accurate temperature dependence assessment is therefore necessary in order to derive (jL) c value at operating conditions.…”