INNOVATVE ACID COPPER PROCESS FOR SIMULTANEOUSLY FILLING VIAS AND PLATING THROUGH HOLES

This paper relates to copper plating processes in the manufacturing of printed circuit boards, IC substrates, and semiconducting devices for electronic applications. The complex circuit hoard designs require simultaneously tilling of via structures and plating through holes (TH). This is highly challenging since the commonly used electrolytes for tilling vias are not suitable for plating of the through holes and vice versa. The requirements include filling BMV, while depositing no more than 18 - 20 mu m of copper onto the planar substrate areas, dimple no more than 10 mu m, and micro-distribution for the plated TH > 75 %. The described DC acid copper plating process is designed for simultaneously filling blind micro-vias and plating through holes across a variety of geometries in a variety of equipment applications with insoluble anodes, including vertical continuous plating equipment, VCP. The bath produces a bright, fine grained, ductile deposit. The thermal and physical mechanical properties of the copper deposits are excellent. Tensile strength > 42,000 psi and elongation > 20 % had been measured for deposits plated in a fresh and in an aged bath. The organic additive ranges have been optimized. All bath components are CVS analyzable and the electrolyte has an extremely long life.