The influence of fluid dynamics on plating electrolyte for the successful production of blind micro-vias: laboratory investigations leading to optimised production equipment

摘要

Successful copper plating of blind micro-vias is very strongly dependant on the effective mass transport of copper ions into the vias. This mass transport limitation is demonstrated by a rough or even in extreme cases at high aspect ratio or high applied current densities, a burnt appearance of the copper deposit at the base of the via. The poor quality of deposited copper has an obvious impact on productivity and also on the feasibility of filling the blind micro-vias required for highest packaging density. This paper describes the methods used to evaluate solution flow in micro-vias carried out in controlled laboratory conditions. The subsequent successful implementation of improved solution flow in simulated production equipment and also in full-scale production is shown. Results are included from horizontal and also vertical processing; in both cases using production equipment operating with reverse pulse plating and insoluble dimensionally stable anodes.