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Improved Electromigration Lifetime for Narrow Al Cu Stripes

IP.com Disclosure Number: IPCOM000082730D
Original Publication Date: 1975-Jan-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Berenbaum, L: AUTHOR [+2]

Abstract

Because of the nature of dispersion of the CuAl(2) precipitate particles in an Al-Cu conductor prior to photoprocessing, there may result a wide spread in properties of the final narrow lines. Because of the variations of Cu and CuAl(2) distribution, lifetime during electromigration is decreased and the value of Sigma, i.e., spread in failure times, increases. A heat treating cycle is described which provides a uniform dispersion of CuAl(2) and Cu to obtain improved electromigration lifetime characteristics, to obtain usefulness of Al-Cu for electron-beam fabricated narrow conductors.

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Improved Electromigration Lifetime for Narrow Al Cu Stripes

Because of the nature of dispersion of the CuAl(2) precipitate particles in an Al-Cu conductor prior to photoprocessing, there may result a wide spread in properties of the final narrow lines. Because of the variations of Cu and CuAl(2) distribution, lifetime during electromigration is decreased and the value of Sigma,
i.e., spread in failure times, increases. A heat treating cycle is described which provides a uniform dispersion of CuAl(2) and Cu to obtain improved electromigration lifetime characteristics, to obtain usefulness of Al-Cu for electron-beam fabricated narrow conductors.

Stripes were quenched from 450 degrees C, and compared with standard stripes, e.g., slow cooled from 450 degrees C. The quenching treatment prevented Cu from precipitating as CuAl , whereas slow cooling allowed a wide dispersion of CuAl(2) particles. The electromigration damage mode changed from one of void formation to general stripe thinning, and significantly longer times were required for failure. During the electromigration of quenched stripes, supersaturated Cu migrated to grain boundaries from the lattice to form a uniform continuous network of CuAl(2), which then broke up into fine dispersions that finally coalesced into larger particles concentrated within triple points in the granular structure. All triple points contained precipitate particles.

Important factors for improving the electromigration lifetime of narr...