Study of copper diffusion through a ruthenium thin film by photoemission electron microscopy

Photoemission electron microscopy is used to study copper diffusion through a ruthenium thin film. The photoemission electron microscopy images display a large contrast between Cu and Ru due to the differences in work function, making photoemission electron microscopy an ideal methodology to study thin film diffusion in real time. Between 175 and 290 degrees C, Cu mainly diffuses through defect sites in the thin Ru film. Uniform diffusion of Cu through the Ru film begins at approximately 300 degrees C. The results are confirmed by x-ray photoemission spectroscopy depth profiling and scanning electron microscopy-energy dispersive x-ray spectroscopy analysis. (c) 2007 American Institute of Physics.