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United States Patent 6,143,655
Forbes, et. al. Nov. 7, 2000

Methods and structures for silver 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 silver. Accordingly, the invention provides a new "self-trenching" or "self-planarizing" method of making coplanar silver 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 silver with the non-oxidized region. The reaction substitutes, or replaces, the non-oxidized region with silver to form silver 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.: 30,113
Filed: Feb. 25, 1998
Intl. Cl. : H01L 21/00, H01L 21/3205, H01L 21/44, H01L 29/40
Current U.S. Cl.: 438/686; 257/742; 257/743; 257/762; 438/46; 438/602; 438/660; 438/752; 438/770; 438/85
Field of Search: 438/602, 686, 660, 658, 85, 46, 752, 770, 779, 796; 257/762, 743, 742

References Cited | [Referenced By]

U.S. Patent Documents
4,702,941Oct., 1987Mitchell et al. 427/250
4,855,252Aug., 1989Peterman et al. 437/189
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
5,710,454Jan., 1998Wu 257/413
5,757,072May, 1998Gorowitz et al. 257/522
5,796,151Aug., 1998Hsu et al. 257/410
5,796,166Aug., 1998Agnello et al. 257/751
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.Drake; Eduardo E.
28 Claims, 12 Drawing Figures

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