Electroless deposition of Cu with solutions containing either Mg2+ or Pd2+ ions

Abstract

The electroless deposition of Cu was carried out with aqueous solutions containing either Pd2+ or Mg2+ ions. The substrate was SiO2 with a TiN/Ti adhesion layer. Copper obtained from electroless deposition had smaller grains, a higher impurity level (Ti Cl, S, Na and Pd) and a higher resistivity than Cu deposited by sputtering. After electroless deposition of Cu with Pd2+ ions, the samples were submitted to a heat treatment in Ar at 500°C. The annealed Cu films had a lower impurity content (Ti, C and S), larger grains as well as a lower resistivity. Copper films obtained by electroless deposition with Mg2+ ions presented a very high O content, a small grain structure as well as a high resistivity. Furthermore, the higher the Mg concentration was in the aqueous solution, the higher was the O level in the Cu and the higher was the resistivity. The Cu resistivity was found to be strongly dependent on the Cu grain size and O content.