Improved adhesion of copper on Al2O3

Summary Improved methods for Al₂O₃ metallization by Cu are described. Good adhesion between Cu and Al₂O₃ substrate depends on the formation of chemical bonds between the substrate and the metallic layer. The temperature needed for the formation of a CuAl₂O₄ spinel interface is reduced from 1050°C to 900°C by the addition of various oxides. The adhesion between the CuAl₂O₄ interface and deposited Cu is stronger then the tensile strength of pure Cu. Plasma techniques for the formation of a Cu containing interface are also described. Bombardment of a Cu film with Xe⁺ ions in a rf-glow discharge implants Cu atoms into the substrate to a depth of 5 nm, as determined by SIMS depth profiling. Methods for reduction of the CuAl₂O₄ surface for subsequent metallization are also presented.