Simulation and experimental determination of the macro-scale layer thickness distribution of electrodeposited Cu-line patterns on a wafer substrate

The impact of adjacent patterned zones with different active area densities on the current density and electrodeposited layer thickness distribution over a wafer substrate is examined, both by experiment and numerical simulation. The experiments consist in running an acid copper plating process on the patterned wafer, and layer thickness measurements by means of X-ray fluorescence (XRF) and atomic force microscopy (AFM). The simulations are based on a potential model approach taking into account electrolyte ohmic drop and electrode polarization effects, combined to a boundary element method (BEM) approach to compute the current density distribution over the electrodes. Experimental and computed layer thickness distributions are in very good agreement.