Copper Oxidation Effect in the EMC/Cu Interfacial Adhesion Improvement for a Novel Copper Interconnection Substrate Application

Copper oxidation structure, cupric oxide (CuO) and cuprous oxide (Cu2O), under Ar/H2 plasma reaction mechanism for the EMC/Cu interface adhesion improvement was studied in this work. This work is utilized TGA to figure out Cu oxidized state and sample preparation, and using plasma treatment Cu oxidation layer to evaluate the EMC/Cu interface adhesion strength by shear testing method. Results show a plasma reduction on Cu oxidation layer provide a better interface adhesion, and the layer structure has a significant composition change, Cu/Cu2O/CuO/EMC → Cu/Cu2O/CuO/Cu2O/EMC. These layer structures were identified by high-resolution TEM mapping with EELS spectrum fitting, it was also verified for CuO reduction to form Cu2O, following the Cu2O hydration would provide much hydrogen-bonding in the EMC/Cu interface. This kind of chain reaction mechanism including CuO reduction and Cu2O hydration was described by 2CuO + H2 → Cu2O +H2O → 2CuOH (hydration molecular). The reaction mechanism of the EMC/Cu bonding has been investigated and verified in this experimental study and our conclusion is that hydrogen bonding on the Cu oxidation layer surface can strengthen the EMC/Cu interface adhesion.