Simulations on the optimum conditions for propargyl alcohol to function as a shape control agent in the process of nickel electrodeposition onto a micropatterned substrate

It was found that the addition of propargy alcohol (PA) to a nickel sulfamate solution was effective for controlling the shape of deposit in the process of nickel electrodeposition onto a micropatterned substrate. The factors, i.e. the electrode potential, the thickness of diffusion layer and the concentration of PA, that affect the shape control function of PA were simulated by the boundary element method, based on the assumption that PA is consumed by diffusion-adsorption-reduction mechanism and that the concentration of PA vary along the cathode/solution interface. The function that represents the variation of PA concentration along the interface was used for the boundary values. The results of simulation explained well the difference in growing habit of the deposits obtained experimentally at different potentials, and figured out the important factors for suppressing the growth in horizontal direction. The optimum conditions for obtaining probe shape deposits were proposed.