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Electromigration Behavior in Layered Ti/AlCu/Ti Films and its Dependence on Intermetallic Structure

Published online by Cambridge University Press:  15 February 2011

K. P. Rodbell ,
P. W. DeHaven  and
J. D. Mis
K. P. Rodbell
Affiliation:
IBM Research Division, Yorktown Heights, NY 10598
P. W. DeHaven
Affiliation:
IBM General Technology Division, Hopewell Junction, NY 12533
J. D. Mis
Affiliation:
IBM General Technology Division, Hopewell Junction, NY 12533
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Abstract

A sputtered aluminum-low copper (Cu concentration < 2wt.%Cu), multilayered, submicron, device interconnect metallurgy consisting of two TiAl3 layers (∼,0.1μm thick) under and over an Al-Cu alloy conductor (0.95μm thick) with either an Al-Cu or TiN cap layer (0.05μm thick) has been developed. These films were patterned by reactive ion etching, and showed both a low susceptibility to corrosion and a low resistivity. Electromigration lifetime data on Al, Al-Cu, and both dc magnetron sputtered and electron gun evaporated multilayered fine lines, fabricated and tested in the same laboratory, are included for a direct comparison. Outstanding electromigration behavior was measured for sputtered, multilayered, submicron films with copper concentrations between 0.12 – 2wt.%Cu. In contrast, electromigration lifetimes of evaporated, multilayered films were found to degrade rapidly at < 2wt.%Cu. This anomalous electromigration behavior was attributed to structural differences in the Ti-Al intermetallics formed. It is proposed that defects present in the Ti-Al superlattice phase cause decreased electromigration performance compared to films in which TiAl3 exclusively forms. Multilevel structures, consisting of CVD W interlevel vias, were also investigated and found to have significantly degraded electromigration performance compared to planar samples. This was attributed to geometric and material flux divergences at the via/conductor interfaces.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 225: Symposium G – Materials Reliability Issues in Microelectronics , 1991 , 91
Copyright
Copyright © Materials Research Society 1991

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