GRAIN-BOUNDARY MISORIENTATION ANGLES AND STRESS-INDUCED VOIDING IN OXIDE PASSIVATED COPPER INTERCONNECTS

Grain boundary misorientations were determined by electron backscatter ing diffraction for tantalum-encapsulated, copper interconnects which contained thermal-stress-induced voids. The misorientation angles at v oided and unvoided line segments were analyzed for two differently hea t treated sample types, which were not equally susceptibile to stress voiding. Unvoided line segments contained a larger percentage of low m isorientation angle, lower diffusivity boundaries than regions adjacen t to voids. In addition, the mow void resistant sample type also conta ined an overall higher proportion of low misorientation angle boundari es than the sample type which exhibited more voiding. The data provide further support for the importance of local variations in microstruct ure, which control the kinetics of stress void formation and growth. ( C) 1997 American Institute of Physics.