Microstructure Evolution with Direct Current Density on Electrodeposited Copper Films

Copper is a state of the art material for the semiconductor and microelectronics industries due its superb electrical properties. Since the replacement of aluminum by copper, in the manufacture of interconnects, the microchip performance and efficiency has been enhanced significantly. However, the market’s continuous demand for faster and more complex integrated circuitry has been pushing the performance of copper to new limits. Thus, microstructure parameters, such as grain size, fraction of twin boundaries, crystallographic defects and crystal orientation, have become critical for achieving outstanding electrical and mechanical properties [1-3]. In this regard, the purpose of this work was to characterize the microstructure evolution of copper films, produced by direct current electrodeposition, under different current densities. Copper films 30-50 μm thick were deposited on a graphite substrate using current densities ranging from 20 to 420 mA/cm2 and an additive-free copper and hydrogen sulfates electrolyte (concentration of 1.0 M and pH of 1.0) at room temperature. The films were detached from the substrate, grinded and fine-polished for electron backscatter diffraction (EBSD) characterization. Subsequently, 3 mm diameter discs were cut-off from the films, grinded and jet polished for transmission electron microscopy (TEM).