Backend-of-line reliability improvement options for 28nm node technologies and beyond

This paper reviews the most encouraging process options for improving backend-of-line reliability performance in advanced technology nodes. Metal capping yields the best electromigration performance; however, this process is most challenging with respect to integration and may also suffer from significantly decreasing grain sizes in trench bottoms for future technologies. Furthermore, time-dependent dielectric breakdown has to be carefully evaluated. Alloying or silicidation techniques are less challenging to implement but can result in unacceptably high resistance increases. We analyze the respective results for each option and compare the performance on 45, 32, and 28 nm technology nodes. In addition to electromigration and time-dependent dielectric breakdown, the impact of the various process options on stress migration performance is discussed.