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13 September 1996 Intermetallic compound formation in hot aluminum metallization and its effect on etching and electromigration
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Application of hot aluminum (or aluminum plug) in deep submicron VLSI metallization has attracted much attention. Studies have shown that introduction of a titanium wetting layer prior to aluminum deposition improves the capability to fill deep submicron contacts/vias with vertical sidewalls in hot aluminum process. In this paper, we report that the introduction of this titanium wetting layer can also greatly improve the aluminum etching process window. Transmission Electron Microscope (TEM) analysis indicates that a continuous layer of TiAl3 intermetallic compound has formed at the AlSi(1%)Cu(0.5%)/Ti interface during hot aluminum deposition. In the case of without titanium wetting layer, TiAl3 compound can also form at AlSiCu/TiN interface but it is not a continuous layer. The formation of the continuous TiAl3 layer is believed to be responsible for the improvement of etching process window. Electromigration lifetime test is also performed on samples with and without titanium wetting layer. While results show that the introduction of titanium wetting layer increases the electromigration lifetime of the hot aluminum metallization, too much TiAl3 formation may degrade the electromigration performance due to its higher resistivity.
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Lianjun Liu, Dong Lu, Pang Dow Foo, Way Tat Tan, Kurt Kowk, Gang Zou, and Man Siu Tse "Intermetallic compound formation in hot aluminum metallization and its effect on etching and electromigration", Proc. SPIE 2875, Microelectronic Device and Multilevel Interconnection Technology II, (13 September 1996);


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