a1 Cascade Engineering Services Inc., Redmond, Washington 98052
a2 Department of Materials Science and Engineering, Lehigh University, Bethlehem, Pennsylvania 18015
Strain evolution in 0.45-μm-thick, 2-μm-wide, and 100-μm-long Cu conductor lines with a passivation layer has been investigated using synchrotron x-ray microdiffraction. A moderate electromigration-current density of 2.2 × 105 A/cm2 was used to minimize Joule heating in the Cu conductor lines. After 120 h of current flowing in the Cu lines at 270 °C, measurements show strain relaxation and homogenization occurring in the Cu lines with current flowing, but not in Cu conductor lines without current. Stronger interaction between electrons with Cu atoms in areas with higher strains was proposed to explain the observation.
(Received November 05 2010)
(Accepted December 28 2010)
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