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Reduced Electromigration Damage in Al Cu Stripes

IP.com Disclosure Number: IPCOM000074676D
Original Publication Date: 1971-May-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 3 page(s) / 32K

Publishing Venue

IBM

Related People

Rosenberg, R: AUTHOR

Abstract

The grain structure of Al-Cu stripes contains a wide distribution of grain size and does not have strong preferred orientation. Superposition of both uniform distribution of grain size and strong preferred orientation are achieved by depositing pure aluminum of ideal stable structure and then adding solute.

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Reduced Electromigration Damage in Al Cu Stripes

The grain structure of Al-Cu stripes contains a wide distribution of grain size and does not have strong preferred orientation. Superposition of both uniform distribution of grain size and strong preferred orientation are achieved by depositing pure aluminum of ideal stable structure and then adding solute.

It has been suggested that the presence of solute in the form of grain boundary ions is necessary to restrict the electromigration of the solvent species, and a relationship was presented which illustrated the expected decrease in solvent electromigration flux as the boundary solute concentration increased. It was also shown how structural discontinuities in a stripe can lead to rapid deterioration in the presence of a solute, under assumption that the solute in an interstitial-type position can move freely. One example of such a discontinuity is the triple point shown in Fig. 1. If J(II) +J(III) > J(I), where J is the flux of solute ions, a depletion occurs at x = 0 and a solute profile as in Fig. 2 results. In this figure , S(b) degrees is the initial solute concentration and S(b)/1/ the depleted concentration. By use of Fig. 2 and the relationship ship connecting the solute boundary concentration, S(b), and solvent flux, J(s), a plot of J(s) vs x is obtained, as shown in Fig. 3. The slope of the curve of Fig. 3 at any point dJ(s)/dx gives the depletion rate of solvent at the triple point. The depletion rate, approximated by J(s)/1/ - J(s)/degrees/ can be greater than the rate without the solute, DeltaJ(o).

The possible lifetime advantage by using solute addition cannot be achieved if local irregularities exist. This problem has been considered for pure aluminum, IBM Technical Disclosure Bulletin, May 1971, Page 3823, and it has been shown that a high degree of preferred orientation and a narrow distribution of grain sizes ...