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Segmented Aluminum Stripe Devices

IP.com Disclosure Number: IPCOM000073465D
Original Publication Date: 1970-Dec-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Ainslie, NG: AUTHOR [+3]

Abstract

Long aluminum stripes have relatively short lifetimes compared with shorter segments during electromigration. On the surface of the longer stripes, especially close to areas of severe damage, are masses of material which have been extruded out of the stripes by a great extrusion pressure.

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Segmented Aluminum Stripe Devices

Long aluminum stripes have relatively short lifetimes compared with shorter segments during electromigration. On the surface of the longer stripes, especially close to areas of severe damage, are masses of material which have been extruded out of the stripes by a great extrusion pressure.

During electromigration in constrained glass topped stripes, the electron wind creates an undersaturation of vacancies downstream leading to a build up of tremendous pressure, as predicted by the Gibbs Thompson equation, which leads to extrusion of the material, damage and ultimate failure. By use of segmented stripe devices, instead of long continuous stripes, this extrusion pressure can be greatly reduced thereby increasing electromigration resistance and lifetime.

During electromigration in an aluminum stripe with a current density j, atoms are transferred from left to right in Drawing B. This leads to a change in vacancy concentration from equilibrium at the left to something less far down stream on the right due to their filling with atoms.

Assume stripe of length X is powered by a current density j which is a pulsating DC signal as shown in Drawings A and B, where Delta t = period of pulse wave RDelta t = time of current pulse; where 1 >/- 0

In the steady state J, average vacancy flux = 0, where J is composed of a flux due to an electromigration force and a flux due to a vacancy concentration gradient force:

(Image Omitted)

Pressure exerte...