A strategic copper plating method without annealing process

An improved copper (Cu) process with a plating current strategy was used to stabilize the residual stress and suppress the void formation. The Cu grain size was inversely proportional to the amplitude of the plating current in the electroplated process, and it dominated the density of the grain boundary due to the aggregation of Cu grain. Therefore, the elimination of the grain boundaries happens in the first thermal cycle and generates a tensile residual stress. The electroplated process by the improved plating current strategy was presented to produce various grain sizes to enhance the interface packing density of the Cu film. This result leads to a higher density of the grain boundaries and is helpful to the grain growth only through the effect of Cu self-annealing. The residual stress maintains a stable value without the thermal treatment. This plating method strategy presents a reliable Cu interconnect process without considering the change in the residual stress.