Tertiary Current Distributions on the Wafer in a Plating Cell
1Keisoku Engineering System Co., Tokyo, Japan
The tertiary current distributions on the wafer in a plating cell are studied in this work. An acid copper sulfate electrolyte composed of CuSO4/5H2O of 2.4 g/L and H2SO4 of 90 g/L is taken into account for copper deposition on the wafer. The solution of shear-plate agitating fluid dynamics is coupled into the calculation of tertiary current distributions. The obtained distributions of tertiary current densities and ion concentrations on the wafer present an oscillating wave form, indicating the strong effect of shear-plate agitation on the current distributions. The distance between the wafer and shear plate is analyzed, which determines the oscillating breadth of the tertiary current distributions on the wafer.