Measurement of strain in Al-Cu interconnect lines with x-ray microdiffraction

We report measurement of strain in patterned Al-Cu interconnect lines with x-ray microdiffraction technique with a similar to 1 mu m spatial resolution. Monochromatized x rays from an undulator were focused on the sample using a phase fresnel zone plate and diffracted light was collected by an area detector in a symmetric, angle dispersive x-ray diffraction geometry. Measurements were made before and after the line sample was stressed for electromigration. Results show an increase in inter- and intra-grain strain variation after the testing. Differences in strain behavior of grains with (111) and (200) crystallographic planes parallel to the substrate surface were observed. A position dependent variation of strain after the testing was measured whereas no such dependence was found before the testing. (C) 1999 American Institute of Physics. [S0021-8979(99)08214-6].