Browse Prior Art Database

Metallurgy Barrier for Au and Pb

IP.com Disclosure Number: IPCOM000076722D
Original Publication Date: 1972-Apr-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Revitz, M: AUTHOR [+4]

Abstract

In this metallurgy concept a barrier layer or Ta is provided between Au and Pb layers to prevent interaction.

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Metallurgy Barrier for Au and Pb

In this metallurgy concept a barrier layer or Ta is provided between Au and Pb layers to prevent interaction.

The value of semiconductor devices utilizing Au metallurgies can be significantly enhanced, by using solder bonds for joining the device to a substrate support. In order to achieve this objective Pb and Au are necessarily in electrical contact, normally in the area of the contact terminals. The Pb Au eutectic which occurs at 219 degrees C necessitates that the two metals be separated by a barrier layer. It is conventional to provide a Ta layer on the top and bottom of a Au stripe. However, the upper Ta layer was noted to be inadequate as a barrier layer between the contact metallurgy, when the device was processed in the normal manner.

In this process, a Ta layer is deposited on a via hole in contact with the underlying Au stripe separating the stripe from the contact pad. An important aspect in the success of the barrier layer is shielding it during fabrication from conventional etchants and resists, which appear to degrade the Ta film to make it ineffective as a barrier. The technique of fabricating consists of depositing a blanket layer of Ta through a via hole 10 in glass layer 12 to establish contact with the metallurgy layer. The metallurgy layer consists of an intermediate Au layer 14, an upper layer 15 of Ta, and a lower layer 16 of Ta separated from the substrate 18 by SiO(2) layer 20. Ta layer 22 is preferably de...