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Chromium Underlay for Electron Beam Resist Lift Off of Tantalum Gold Metallurgy

IP.com Disclosure Number: IPCOM000080526D
Original Publication Date: 1974-Jan-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Anderson, LC: AUTHOR [+3]

Abstract

In the formation of narrow tantalum-gold-tantalum interconnect lines for integrated circuits by the lift-off technique, an electron-gun evaporated chromium underlayer is used to avoid cracking of the tantalum and photoresist, which would result in loss of the interconnect lines.

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Chromium Underlay for Electron Beam Resist Lift Off of Tantalum Gold Metallurgy

In the formation of narrow tantalum-gold-tantalum interconnect lines for integrated circuits by the lift-off technique, an electron-gun evaporated chromium underlayer is used to avoid cracking of the tantalum and photoresist, which would result in loss of the interconnect lines.

A relatively thick photoresist layer is formed on the surface of the substrate which will carry the interconnect metallurgy. The photo-resist layer is imaged and developed to expose the portions of the substrate upon which the interconnect lines are to be formed. A 750 Angstrom thick blanket layer of chromium is first evaporated onto the exposed portions of the substrate and the photoresist layer, by electron-gun evaporation.

The tantalum-gold-tantalum metallurgy layers are then electron-gun evaporated at a temperature of about 80 degree C. The lower tantalum layer can have a thickness greater than about 150 angstroms without degrading the resist. This thickness of tantalum can be used to incorporate the barriers needed to avoid the alloying of gold and silicon in the contact holes. The process is completed by the solvent lift-off of the photoresist and the overlying metal layers.

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