Etching Feasibility of CoWP and CoWB as Selective Metallic Capping Layer in Cu Dual Damascene Interconnection

Abstract

Recently, CoWP and CoWB have been applied as metallic-cap materials owing to their electrical conductivity and adhesion with Cu. However, when a metallic cap of CoWP and CoWB is applied, current leakage occurs because of damage caused by the misalignment and over-etching. Therefore, the etch process must be optimized to minimize the damage to the metallic cap. In this study, the problems occurring in the etch process were analyzed to minimize the damage of the metallic cap and optimize the surface morphology. Thus, it was confirmed that the etch damage is a major cause of damage owing to misalignment in the application of the metallic cap, and a via trench etch process is possible when CoWB is applied as a metallic-cap material instead of CoWP.