Non-correlated behavior of sheet resistance and stress during self-annealing of electroplated copper

A study of the sheet resistance and stress of electrochemically deposited (ECD) blanket copper layers on a TaN barrier shows that the time dependence of these two parameters are not necessarily the same. This indicates that they are not simply interconnected through the grain size distribution changes occurring at room temperature. The plating bath composition and the resulting contaminant incorporation in the Cu layer during ECD has been identified as an additional important parameter in the explanation of the self-annealing behavior.