Thermal and electromigration-induced strains in polycrystalline films and conductor lines: X-ray microbeam measurements and analysis

Abstract

X-ray microbeam measurements of thermal and electromigration-induced strains have been made at NSLS using white-beam energy dispersive x-ray diffraction, averaging over many grains, and at APS using white-beam Laue x-ray diffraction, from single grains. Grain-by-grain deviatoric strain measurements in Al films show wide variation in behavior for different grains in the films. Room temperature relaxation of residual strains was observed to occur at different rates for Al films with different bonding layers and substrates. X-ray microbeam measurements of strain development during electromigration for Cu and Al conductor lines show that strain gradients do not develop in the copper lines under conditions similar to those for which large strain gradients have been seen for Al lines. © 2006 American Institute of Physics.