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In-Situ X-Ray Microbeam Cu Fluorescence and Strain Measurements on Al(0.5 AT.% Cu) Conductor Lines During Electromigration

Published online by Cambridge University Press:  10 February 2011

H.-K. Kao
Affiliation:
Lehigh University, Bethlehem, PA 18015, gsc3@lehigh.edu
G. S. Cargill III
Affiliation:
Lehigh University, Bethlehem, PA 18015, gsc3@lehigh.edu
K. J. Hwang
Affiliation:
Lehigh University, Bethlehem, PA 18015, gsc3@lehigh.edu
A. C. Ho
Affiliation:
Lehigh University, Bethlehem, PA 18015, gsc3@lehigh.edu
P.-C. Wang
Affiliation:
IBM Microelectronics, Hopewell Junction, NY 12533
C.-K. Hu
Affiliation:
IBM Research, Yorktown Heights, NY 10598
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Abstract

We have used x-ray microbeam fluorescence and diffraction for in-situ measurements of Cu concentration and strain during 36 hours of electromigration with current density 5×105 A/cm2 at temperature 310°C for a passivated 10μm-wide, 200μm-long Al(0.5 at.% Cu) conductor line. These measurements indicate that Cu is quickly depleted at the cathode end of the line and is piled up at the anode end, where the Cu concentration first increases, then decreases, and finally remains constant. A void begins growing at the cathode end of the line about two hours after the start of current flow, with a nearly constant void growth rate of 1 μm/hr for the remainder of the test. The evolution of stresses within the line during electromigration involves changes by 100's of MPa and is more complex than seen previously for electromigration under similar conditions for pure Al conductor lines.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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