Behavior of TiN and Ti Barrier Metals in Al‐Barrier‐Al Via Hole Metallization

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Abstract
The behavior of and Ti barrier metals in Al‐barrier‐Al via structures was investigated. When a reactive‐sputtered film is deposited onto an Al‐1 weight percent (w/o) Si‐0.5 w/o Cu surface, is formed at the interface due to the reaction of to Al, and causes an increase in via contact resistance. To suppress the increase in via contact resistance, it is crucial to interpose a Ti buffer layer at the interface. The via contact resistance of the structure increases at annealing temperatures over 450°C, since is formed at both the and interfaces. The via contact structure presents a specific low resistance after annealing above 450°C, is formed at both the Al/Ti and Ti/Al interfaces. Further, the layer can improve the electromigration performance of the interconnection which consists of a structure. The electromigration performance for various via structures also was investigated. Al/Ti/Al and via contact structures tend to increase the chain resistance before via open failure, where the dominant mechanism is the void formation originating from the migration of Al atoms in the vias rather than the via lift‐off mode. This means that Al atoms migrate easier on a layer than on a Ti layer. As a result, an Al/Ti/Al via structure is better for electromigration performance.

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