Browse Prior Art Database

Metal Etch Stop Under Interconnect Metallurgy

IP.com Disclosure Number: IPCOM000037349D
Original Publication Date: 1989-Dec-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Halbach, RE: AUTHOR [+3]

Abstract

By applying a thin layer of an appropriate metal, e.g., cobalt (Co), just prior to the deposition of interconnection metal, e.g., aluminum- copper (Al-Cu), reactive ion etching (RIE) stops after complete removal of the Al-Cu when forming interconnection lines. Selective wet etch removal of the exposed thin Co is achieved with a dilute solution of nitric acid (HNO3). Thus, damage to contacts is avoided since there is never direct exposure of materials under the metallurgy to the RIE process.

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Metal Etch Stop Under Interconnect Metallurgy

By applying a thin layer of an appropriate metal, e.g., cobalt (Co), just prior to the deposition of interconnection metal, e.g., aluminum- copper (Al-Cu), reactive ion etching (RIE) stops after complete removal of the Al-Cu when forming interconnection lines. Selective wet etch removal of the exposed thin Co is achieved with a dilute solution of nitric acid (HNO3). Thus, damage to contacts is avoided since there is never direct exposure of materials under the metallurgy to the RIE process.

For highest device density, metal contact size equal to contact hole opening size is required. Slight misalignment of a photomask for metal etching relative to contact holes can result in exposure of contact diffusions to damage by the RIE process. The figure shows such a misalignment of a metal line 8 and a via hole in insulating layer 6. A Co layer 10 is deposited as shown to form an etch stop and barrier to damage of the exposed portion of contact diffusion 2 in silicon substrate 4 at the end of the RIE process creating metal line 8. Exposed Co 10 is removed by selective wet etching in dilute HNO3.

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