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United States Patent 5,920,121
Forbes, et. al. Jul. 6, 1999

Methods and structures for gold interconnections in integrated circuits

Abstract

A typical integrated-circuit fabrication requires interconnecting millions of microscopic transistors and resistors with aluminum wires. Making the aluminum wires flush, or coplanar, with underlying insulation requires digging trenches in the insulation, and then filling the trenches with aluminum to form the aluminum wires. Trench digging is time consuming and costly. Moreover, aluminum has higher electrical resistance than other metals, such as gold. Accordingly, the invention provides a new "self-trenching" or "self-planarizing" method of making coplanar gold 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 gold with the non-oxidized region. The reaction substitutes, or replaces, the non-oxidized region with gold to form gold wires 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 resistance and capacitance which, in turn, enable faster, more-efficient integrated circuits.


Inventors: Forbes; Leonard (Corvallis, OR); Farrar; Paul A. (So. Burlington, VT); Ahn; Kie Y. (Chappaqua, NY).
Assignee: Micron Technology, Inc. (Boise, ID).
Appl. No.: 30,188
Filed: Feb. 25, 1998
Intl. Cl. : H01L 23/48, H01L 23/52, H01L 29/40
Current U.S. Cl.: 257/742; 257/522; 257/743
Field of Search: 257/742, 616, 743, 744, 745, 276, 522

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
5,757,072May, 1998Gorowitz et al. 257/522
5,801,444Sept., 1998Aboelfotah et al. 257/742

Foreign Patent Documents
5-275682Oct., 1993JP 257/742
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Primary Examiner: Martin-Wallace; Valencia
Assistant Examiner: Clark; S. V.
Attorney, Agent or Firm: Schwegman, Lundberg, Woessner & Kluth, P.A.
17 Claims, 12 Drawing Figures

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