Formation of Cr-O and Cr-N-O films serving as Cu oxidation resistant layers and their N2 pre-sintering effect

This study investigates the Cu oxidation resistant layers of sputter deposited Cr-O and reactively sputter deposited Cr-N-O of 200 Angstrom thickness. with and without, thermal N-2 pre-sintering treatment. The resistance against Cu oxidation (or the highest annealing temperatures without causing Cu oxidation) of the Cr-O and Cr-N-O covered Cu films were found to be 350 and 500 degrees C, respectively, in an O-2 ambient. The inherent defects in the Cr-O lavers and the nitrogen doping in the Cr-N-O layers were believed to be the principal causes for the distinction of the resistance against Cu oxidation. With Na pre-sintering treatments on the Cr-O or Cr-N-O covered Cu films, the ability of resistance against Cu oxidation was degraded. The higher the N-2 pre-sintering temperature was, the lower the oxidation temperature of Cu became. The N-2 pre-sintering thermal process led to formation of defects on the Cr-O and Cr-N-O layers, resulting in the degradation of the ability of resistance against Cu oxidation. Thus, the application of Cr-O or Cr-N-O as a resistant layer against Cu oxidation should avoid such an excess thermal treatment. (C) 1998 Elsevier Science S.A. All rights reserved.