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Passivation Design / Electromigration Performance Correlations in Layered Aluminum Metallizations

Published online by Cambridge University Press:  22 February 2011

Carole D. Graas
Affiliation:
Texas Instruments Inc. Dallas, TX 75265
Larry L. Ting
Affiliation:
Texas Instruments Inc. Dallas, TX 75265
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Abstract

The study presented in this paper establishes correlations between key passivation morphological characteristics and metal electromigration performance. This was done by using test structures including extrusion monitors which provided narrow gaps along both sides of the test stripes. The parameters studied were: (1) the nature of the gap filling (oxide process and step coverage), (2) local oxide planarization, and (3) oxide thickness above the leads tested. Failure analysis was conducted by SEM cross-sections of cracked passivation areas. We observed that in the case of aluminum metallizations capped by a thin anti-reflective coating (ARC) layer, failure occurred in all cases by aluminum extrusion from the top corners of the leads, and at 45 degree angles into the passivation. Ultimately, the lifetime was dependent on oxide thickness above the test leads rather than gap-filling characteristics.

Type
Research Article
Copyright
Copyright © Materials Research Society 1994

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References

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