Copper deposition on micropatterned electrodes from an industrial acid copper plating bath

摘要

Copper was deposited on micropatterned electrodes in a parallel plate reactor (PPR) using an industrial acid copper plating bath, and the deposit thickness distributions were measured. The plating bath contained, besides copper sulfate and sulfuric acid as main components, small amounts of sodium chloride and an organic additive LP-1~(TM). Copper deposition was carried out under various flow conditions (laminar and turbulent) and applied current densities. Three patterns, each of them consisting of a series of parallel copper microtracks, were manufactured on the electrode surface. The pattern position was chosen to be parallel or perpendicular to the flow direction, corresponding to the two extreme positions for the industrial plating process of patterned electrodes, in casu the round pattern tracks of minicoils. A multi-ion model was used to simulate copper deposition from sulphuric acid solutions, taking into account flow phenomena controlling the mass transfer rate, and the deposition kinetics. The differential equations were solved numerically by use of the multidimensional upwinding method (MDUM). Copper deposition on plane electrodes was investigated and compared to cd distributions obtained from MDUM-simulations. For the case of perpendicular pattern position in laminar flow, the deposit growth in the vias was also modelled and simulated numerically.