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Subtractive Etching of Copper Doped Aluminum

IP.com Disclosure Number: IPCOM000074866D
Original Publication Date: 1971-Jun-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Marinello, DA: AUTHOR [+2]

Abstract

A thin layer of copper sandwiched between aluminum layers may be used to produce copper-doped aluminum interconnection lines for integrated circuits. Etchants for such aluminum-copper-aluminum metallurgy must produce even etching of the aluminum-copper-aluminum without undercutting the copper. Such results are difficult to obtain due to the different reactivities of aluminum and copper with etchants.

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Subtractive Etching of Copper Doped Aluminum

A thin layer of copper sandwiched between aluminum layers may be used to produce copper-doped aluminum interconnection lines for integrated circuits. Etchants for such aluminum-copper-aluminum metallurgy must produce even etching of the aluminum-copper-aluminum without undercutting the copper. Such results are difficult to obtain due to the different reactivities of aluminum and copper with etchants.

Very even etching without undercutting of aluminum-copper-aluminum may be obtained with an etchant having the following formulation: Ingredient Amount H(3)PO(4) (85 weight percent solution) 75 weight percent H(2)O(2) (30 weight percent solution) 3.5 weight percent H(2)O 21.5 weight percent IGEPAL* CO-530 wetting agent two drops.

In use of the etchant, the aluminum-copper-aluminum layers to form the interconnections are covered with photoresist using conventional techniques to mask the metallurgy where etching is no desired. The metallurgy is then immersed in the etchant at a temperature of 35 to 50 degrees C with ultrasonic agitation, to allow removal of the metallurgy in areas not covered by photoresist. Excellent edge definition of the interconnections results, with no undercutting of the copper. * Trademark of General Aniline & Film Corp.

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