Liquid electrolytes (i.e. acids and bases) can be used to pattern metal and semiconductor surfaces. The removal process is an electrochemical surface reaction that is often dependent on reactant and product concentrations, therefore non-homogenous etch rates are common. STAR-CCM+ can be used to aid understanding and optimization of wet-etch processes by predicting these concentration dependent etch rates. The above images show etch-product concentration and etch profiles along a copper surface at the bottom of a two-dimensional trench.