Grain Boundary Chemistry in Al-Cu Metallizations as Determined by Analytical Electron Microscopy

Conference · Sun Mar 31 23:00:00 EST 1991 · Materials Research Society Symposia Proceedings

DOI:https://doi.org/10.1557/proc-229-303· OSTI ID:5981666

Michael, J. R. ^[1]; Romig Jr., A. D. ^[1]; Frear, D. R. ^[1]

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1. Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

Al with additions of Cu is commonly used as the conductor metallizations for integrated circuits (ICs). As the packing density of ICs increases, interconnect lines are required to carry ever higher current densities. Consequently, reliability due to electromigration failure becomes an increasing concern. Cu has been found to increase the lifetimes of these conductors, but the mechanism by which electromigration is improved is not yet fully understood. In order to evaluate certain theories of electromigration it is necessary to have a detailed description of the Cu distribution in the Al microstructure, with emphasis on the distribution of Cu at the grain boundaries. In this study analytical electron microscopy (AEM) has been used to characterize grain boundary regions in an Al-2 wt.% Cu thin film metallization on Si after a variety of thermal treatments. The results of this study indicate that the Cu distribution is dependent on the thermal annealing conditions. At temperatures near the θ phase (CuAl₂) solvus, the Cu distribution may be modelled by the collector plate mechanism, in which the grain boundary is depleted in Cu relative to the matrix. At lower temperatures, Cu enrichment of the boundaries occurs, perhaps as a precursor to second phase formation. Natural cooling from the single phase field produces only grain boundary depletion of Cu consistent with the collector-plate mechanism. The kinetic details of the elemental segregation behavior derived from this study can be used to describe microstructural evolution in actual interconnect alloys.

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5981666
• Report Number(s): SAND--91-0933C; CONF-910406--6; ON: DE91012007
• Journal Information: Materials Research Society Symposia Proceedings, Journal Name: Materials Research Society Symposia Proceedings Vol. 229; ISSN 0272-9172
• Publisher: Springer Nature
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM BASE ALLOYS
COPPER
COPPER ALLOYS
CRYSTAL STRUCTURE
DISTRIBUTION
ELECTRON MICROSCOPY
ELECTRONIC CIRCUITS
ELEMENTS
GRAIN BOUNDARIES
HEAT TREATMENTS
INTEGRATED CIRCUITS
METALS
MICROELECTRONIC CIRCUITS
MICROSCOPY
MICROSTRUCTURE
SEGREGATION
TRANSITION ELEMENTS