Self-encapsulation effects on the electromigration resistance of silver lines

Silver, the most conductive room-temperature material, has drawn attention as a potential interconnect replacement material. In this study, Ag lines w ere self-encapsulated by annealing a Ag/Ti/SiO2/Si structure in a flowing N H3 ambient. The microstructure of this structure after the anneal was studi ed by the use of cross-section transmission electron microscopy (XTEM). Upo n the anneal, the Ag surface was encapsulated by a TiN(O) layer, and a bila yer formed at the initial Ti/SiO2 interface. Electromigration testing shows that the self-encapsulation process improved the electromigration resistan ce of the Ag lines substantially by inhibition of the surface diffusion of Ag atoms. (C) 2001 Elsevier Science B.V. All rights reserved.