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United States Patent 6,121,126
Ahn, et. al. Sept. 19, 2000

Methods and structures for metal interconnections in integrated circuits


A typical integrated-circuit fabrication requires interconnecting millions of microscopic transistors and resistors with metal wires. Making the metal wires flush, or coplanar, with underlying insulation requires digging trenches in the insulation, and then filling the trenches with metal to form the wires. Trench digging is time consuming and costly. Accordingly, the invention provides a new "trench-less" or "self-planarizing" method of making coplanar metal wires. Specifically, one embodiment forms a first layer that includes silicon and germanium; oxidizes a region of the first layer to define an oxidized region and a non-oxidized region; and reacts aluminum or an aluminum alloy with the non-oxidized region. The reaction substitutes, or replaces, the non-oxidized region with aluminum to form a metallic wire coplanar with the first layer. Another step removes germanium oxide from the oxidized region to form a porous insulation having a very low dielectric constant, thereby reducing capacitance. Thus, the present invention not only eliminates the timing-consuming, trench-digging step of conventional methods, but also reduces capacitance which, in turn, enables faster, more-efficient integrated circuits.

Inventors: Ahn; Kie Y. (Chappaqua, NY); Forbes; Leonard (Corvallis, OR); Farrar; Paul A. (S. Burlington, VT).
Assignee: Micron Technologies, Inc. (Boise, ID).
Appl. No.: 30,430
Filed: Feb. 25, 1998
Intl. Cl. : A01L 21/28
Current U.S. Cl.: 438/602; 438/46; 438/619; 438/688; 438/752; 438/770; 438/779
Field of Search: 438/688, 85, 46, 602, 660, 658, 752, 770, 779, 796, 619, 618; 257/765, 771, 743, 542

References Cited | [Referenced By]

U.S. Patent Documents
4,702,941Oct., 1987Mitchell et al. 427/250
4,959,705Sept., 1990Lemnious 257/522
5,148,260Sept., 1992Inoue et al. 257/276
5,187,560Feb., 1993Yoshida et al. 257/743
5,324,684Jun., 1994Kermani et al. 437/95
5,341,016Aug., 1994Prall et al. 257/412
5,371,035Dec., 1994Pfiester et al. 437/69
5,470,801Nov., 1995Kapoor et al. 437/238
5,510,645Apr., 1996Fitch et al. 257/522
5,563,448Oct., 1996Lee et al. 257/742
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5,757,072May, 1998Gorowitz et al. 257/522
5,796,151Aug., 1998Hsu et al. 257/410
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5,801,444Sept., 1998Aboelfotah et al. 257/742
5,925,918Jul., 1999Wu et al. 257/413
5,942,799Aug., 1999Danek et al. 257/751

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Primary Examiner: Niebling; John F.
Assistant Examiner: Nguyen; Ha Tran
Attorney, Agent or Firm: Schwegman, Lundberg, Woessner & Kluth, P.A.
28 Claims, 12 Drawing Figures

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