THE MICROSTRUCTURAL STABILITY OF AL(CU) LINES DURING ELECTROMIGRATION

We have used transmission electron microscopy to examine in detail how microstructural changes take place in aluminum/copper lines adjacent to tungsten contacts during electromigration testing. Observations mad e on aluminum-4% copper lines show that significant changes in the gra in structure surrounding precipitates occur during testing even under conditions where grain growth is not normally observed in the lines. G rain coarsening and precipitate growth produced by the applied current result in the formation of new diffusion blocking structures in the l ines which are likely to significantly influence their time to failure . (C) 1995 American Institute of Physics.