ELECTRICAL-RESISTIVITY OF COPPER AND NICKEL THIN-FILM INTERCONNECTIONS

The resistivity and temperature coefficient of resistivity of copper and nickel thin films used as high-density interconnections in hybrid packages have been measured in the temperature interval 298-723 K. The effects of film thickness, deposition conditions, and postdeposition anneal were analyzed in detail. Minimum as-deposited resistivities approximately 18% and 80% above bulk values could be achieved under optimized deposition conditions for 1-μm-thick copper and nickel films, respectively. Contributions to the resistivity values attributable to electron scattering at phonons, surfaces, impurities, grain boundaries, and intragranular defects were also established. Although subsequent annealing had little impact on the resistivity of copper, a significant reduction in the resistivity of nickel was observed, due primarily to dislocation sinking. Lastly, the relationship of resistivity to the temperature coefficient of resistivity for both metal films was found to be in agreement with Matthiessen's rule.