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Inhibition of Electromigration in Thin Films by Use of Preferred Orientation

IP.com Disclosure Number: IPCOM000074674D
Original Publication Date: 1971-May-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Attardo, MJ: AUTHOR [+4]

Abstract

Electromigration in films is considered to occur primarily by a grain boundary diffusion mechanism. The flux of ions transported in a particular boundary depends on the relative diffusivity associated with that boundary, i.e., if diffusivity is low, ionic mobility and rate of electromigration are correspondingly low. It has been pointed out that damage in a film results from a divergence in the flux such that mass depletion occurs in particular locations in the stripe. One such location is the intersection between grain boundaries of differing diffusion characteristics such that ions do not enter and leave the intersection at equal rates, thus resulting in a net loss (or gain) in the number of ions present.

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Inhibition of Electromigration in Thin Films by Use of Preferred Orientation

Electromigration in films is considered to occur primarily by a grain boundary diffusion mechanism. The flux of ions transported in a particular boundary depends on the relative diffusivity associated with that boundary, i.e., if diffusivity is low, ionic mobility and rate of electromigration are correspondingly low. It has been pointed out that damage in a film results from a divergence in the flux such that mass depletion occurs in particular locations in the stripe. One such location is the intersection between grain boundaries of differing diffusion characteristics such that ions do not enter and leave the intersection at equal rates, thus resulting in a net loss (or gain) in the number of ions present.

To prevent failure of film stripes by electromigration it is desirable to decrease grain boundary diffusivity and to reduce variation between boundaries. This not only decelerates the overall ion mobility but also minimizes the number of sites where divergencies can occur. Highly oriented films are used in which all grains have a common axis normal to the specimen surface, e.g., <111> texture. The boundaries thus produced are of a tilt type whereby most structural defects, e.g., ledges and dislocations, will be parallel to the texture axis. Diffusivity in the direction of the electron flow is in a direction perpendicular to the defects on which diffusion normally occurs and a reduced rate will be...