Browse Prior Art Database

Glass Damage Etch for Integrated Circuit Terminal Metallurgy

IP.com Disclosure Number: IPCOM000090279D
Original Publication Date: 1969-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Aimi, BR: AUTHOR [+2]

Abstract

To inspect a glass passivation layer of integrated circuit devices for damage after chrome-copper-gold contact metallurgy is applied, it is necessary to remove the contact metallurgy. This is done by using nitric acid followed by hydrochloric acid to cause complete removal of the chromium. The hydrochloric acid solution then removes aluminum conducting lines underlying the contact metallurgy, often causing destruction of the glass passivation layer which is the object of the inspection.

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Glass Damage Etch for Integrated Circuit Terminal Metallurgy

To inspect a glass passivation layer of integrated circuit devices for damage after chrome-copper-gold contact metallurgy is applied, it is necessary to remove the contact metallurgy. This is done by using nitric acid followed by hydrochloric acid to cause complete removal of the chromium. The hydrochloric acid solution then removes aluminum conducting lines underlying the contact metallurgy, often causing destruction of the glass passivation layer which is the object of the inspection.

Sufficient removal of the chrome-copper-gold metallurgy to allow glass damage inspection is accomplished by using an etch solution consisting of 90 per cent by volume of concentrated nitric acid and 10 per cent by volume of concentrated hydrochloric acid. Hydrochloric acid in such a solution is unstable, but it is active for a sufficient time to allow removal of the contact metallurgy if freshly prepared for use. By the time the chromium layer is exposed, the concentration of hydrochloric acid is greatly reduced due to reaction with the nitric acid. Further etching is therefore prevented. The glass passivation layer and aluminum conducting lines are not attacked and can now be inspected through the remaining chromium layer of the contact metallurgy.

If the device undergoes sufficient solder reflow processing to cause interdiffusion of the three contact metals, sufficient removal of the contact metallurgy to allow glass d...