Browse Prior Art Database

Method for Making Micron-Size Cylindrical Lines

IP.com Disclosure Number: IPCOM000120852D
Original Publication Date: 1991-Jun-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Cronin, JE: AUTHOR [+3]

Abstract

To reduce wiring capacitance while maintaining required line resistance and line density, a wire having a circular cross-section is desirable. Micron size conductive lines having approximately circular cross- section are made by creating a semicircular depression in an insulator, over-filling the semicircular depression with metal, and approximating a semicircular top half of the cross-section of the metal line by any of several shaping processes.

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This is the abbreviated version, containing approximately 98% of the total text.

Method for Making Micron-Size Cylindrical Lines

      To reduce wiring capacitance while maintaining required
line resistance and line density, a wire having a circular
cross-section is desirable.  Micron size conductive lines having
approximately circular cross- section are made by creating a
semicircular depression in an insulator, over-filling the
semicircular depression with metal, and approximating a semicircular
top half of the cross-section of the metal line by any of several
shaping processes.

      Referring to Fig. 1, insulating layer 10, which remains as part
of the device structure, is deposited on substrate 12.  A second
layer 14 is deposited which does not necessarily remain as part of
the device structure. Photoresist 16 is applied and exposed to a beam
of light or electrons having a flux distribution resulting in a
near-semicircular bottom in the developed cross-section, as shown.
Relatively non- selective anisotropic etching is then used to project
the developed photoresist shape into layer 14 and subsequently into
layer 10, as shown.

      Referring to Fig. 2, photoresist is removed by selective
etching and conductor 18 is conformally deposited to completely fill
the etched depression and then planarized to expose layer 14.

      As shown in Fig. 3, layer 14 is selectively removed, thus over-
filling the semicircular depression in layer 10. The top half of
conductive line 18 is shaped to approximate a semicircle by any of
several means...