XPS analysis of Cu-glass interface obtained by RF ion-plating

The XPS (X-ray photoemission spectroscopy) analysis of the Cu-SiO ₂ interface was undertaken to obtain a better understanding of the cause of the enhanced adhesion reported in ion-plated films. The results indicate the formation of a (Cu₂O)_xSi interfacial layer, nearly 50 Å thick, lying mostly on the Cu side of the interface. Theories of metal-glass adhesion suggest that this (Cu ₂O)_xSi layer leads to chemical bonding between Cu and SiO₂ and is responsible for the enhanced adhesion of the ion-plated films. Because of the reported low reactivity of Cu with SiO ₂ it is believed that the use of negative substrate bias along with the (Cu+Ar) plasma in RF ion plating aids in the chemical reaction between Cu and SiO₂