Back stress model on electromigration lifetime prediction in short length copper interconnects

The short length on the electromigration lifetime is a useful effect to increase current limits in advanced circuits. A way to increase current limit is to consider the Blech effect. The electromigration threshold due to Blech effect in copper interconnect for 65 nm and 45 nm technology is reported in this study. The critical product (jL)c was determined by varying the metal length and stress current density. The higher (jL)c value is obtained for lower stress current, shorter metal lead and 65 nm technology with higher hardness ILD. Finally, this critical product (jL)c as the accelerated EM length factor was used to predict the lifetime. It is shown that the lifetimes of short leads with less than 5 mum have at least 9.52 and 1.45 times higher than that of 250 mum metal lead for 65 nm and 45 nm technology, respectively.