Masaru Naito

Electromigration Characteristics of Sputtered TiN/Ti/AlSiCu/TiON/Ti Interconnects with Aluminum Reflow

Electromigration-induced failures in sputtered TiN/Ti/AlSiCu/TiON/Ti interconnects with aluminum (Al) reflow treatment have been studied in terms of aluminum microstructure and stress relaxation between the AlSiCu and TiON barrier metal. The sputtered interconnects with Al reflow treatment have an electromigration lifetime three times longer than the sputtered interconnects without Al reflow treatment. Furthermore, electromigration-induced voids in sputtered interconnects without Al reflow treatment are generated at the interface between the AlSiCu and TiON. Voids in sputtered interconnects with Al reflow treatment are seldom generated at the interface between the AlSiCu and TiON. The difference in electromigration performance between the two metallizations cannot be explained merely by the orientations of aluminum crystallites and the grain size of the aluminum. We conclude 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 the electromigration resistance of sputtered interconnects with Al reflow treatment. On the contrary, the residual compressive strain lowers the electromigration resistance in sputtered interconnects without Al reflow treatment.

Roles of Cap‐Metal on Via Electromigration Resistance in Aluminum‐Based Interconnections

Cap-metal of the lower metal can be partially etched at shallow via contacts in actual LSI devices. Influence of the cap-metal which partially remains in via contacts on via electromigration (EM) was investigated in cases where the cap-metal was WSi and TiN/Ti. The EM lifetime of via contacts where cap-metal remains is longer than that of via contacts where cap-metal is partially etched when using WSi cap-metal. However, the EM lifetime of via contacts where cap-metal is etched partially is longer than that of via contacts where cap-metal remains when using the TiN/Ti cap-metal. These mechanisms are discussed. Furthermore, EM characteristics of via contacts where aluminum and aluminum are connected directly are reinvestigated and also discussed.

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...