Investigations of the interaction between different barrier metals and copper surface during the chemical-mechanical polishing

We investigated the copper surface during chemical-mechanical polishing (CMP) by measurements of the mixed corrosion potential. The acceleration of the W or Ti polish rate can be explained by the galvanic coupling between Cu and barrier metal. Using patterned wafers we examined the influence of different barrier metal on the copper passivation layer and the copper dishing effect. The formation of Cu pattern by CMP is based on the planarization ability of the process during the removal of the passivations layer. The planarization ability is geometry dependent and has also an effect on Cu dishing.