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PROCESS FOR DEPASSIVATING Cr/Cu/Cr METALLURGY FIRED AT HIGH TEMPERATURE

IP.com Disclosure Number: IPCOM000035702D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Powell, JL: AUTHOR

Abstract

This process provides a technique for depassivating a highly passivated layer of chromium to assure good electrical conductivity between metallurgy layers that make contact through vias.

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PROCESS FOR DEPASSIVATING Cr/Cu/Cr METALLURGY FIRED AT HIGH TEMPERATURE

This process provides a technique for depassivating a highly passivated layer of chromium to assure good electrical conductivity between metallurgy layers that make contact through vias.

In metallurgy systems utilizing chromium-copper-chromium, chromium-silver- chromium, or similar metallurgies, a problem frequently occurs in depassivating the upper chromium layer exposed through a via in a dielectric layer. When the exposed chromium is subjected to heat treatments as, for example, in depositing the dielectric layer at 800-820oC, a chromium oxide layer in the exposed via sites is formed. The standard KMnO4 solutions used to remove the chromium layer are not sufficient for depassivating or removing the chromium oxide layer. If the chromium oxide layer is not removed, excessive resistance is formed between the metallurgy layers.

This technique alleviates the aforementioned problem. The top exposed chromium layer can be depassivated by exposing the passivated chromium to an aqueous solution of HCl containing zinc metal at an elevated temperature. The zinc metal is needed in the mixture to depassivate the chromium oxide.

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