Kinetics of Cu₃Ge formation and reaction with Al

Cu₃Ge films have been found to have a low resistivity, good adhesion on SiO₂, good thermal stability on Si, and good oxidation resistance. It has the potential as an ideal adhesion/barrier/ passivation layer for Cu ultralarge scale integration metallization. The kinetics of Cu₃Ge formation and the thermal stability of Cu₃Ge against Al were studied by in situ resistivity measurement, Rutherford backscattering spectrometry, and transmission electron microscopy. We found that Cu reacted with Ge in the temperature range of 100-200°C. The activation energy of the Cu-Ge compound formation was found to be 1.1±0.1 eV. The Cu-Ge compound was identified as ε-Cu₃Ge from transmission electron microscope diffraction patterns. Upon annealing the ε-Cu₃Ge became unstable on Al at the temperature range of 300-350°C. In the reaction between Al and Cu₃Ge, Cu preferentially reacted with Al to form an ε-Al₂Cu₃ compound. The activation energy of formation of the Al-Cu compound was found to be 2.1±0.1 eV. © 1997 American Institute of Physics.