Masayoshi Omura

Aluminum reflow and electromigration characteristics of sputtered TiN/Ti/AlSiCu/TiON/Ti interconnects

Aluminum (Al) reflow is suppressed in TiN/Ti/AlSiCu/Ti/TiON/Ti interconnects because the interfacial AlxTi layer hinders the migration of Al atoms during reflow annealing. Therefore, electromigration (EM) characteristics of sputtered TiN/Ti/AlSiCu/TiON/Ti interconnects with Al reflow were investigated. The sputtered interconnects with Al reflow treatment have a three times longer electromigration lifetime than the sputtered interconnects without Al reflow treatment. The difference in EM performance between the two metallizations cannot be explained merely by 〈111〉 orientation of Al crystallites and the grain size of Al. We verify that the most effective factor in electromigration performance is the stress relaxation between AlSiCu and TiON during reflow annealing. The negligible residual compressive strain has little influence on EM resistance of sputtered interconnects with Al reflow treatment. On the contrary, the residual compressive strain lowers the EM resistance in sputtered interconnects without Al...