Method and apparatus for adjusting plating solution flow characteristics at substrate cathode periphery to minimize edge effect

A method of forming metallized bumps on predetermined terminal areas of a planar substrate, said bumps being of substantially uniform height across said substrate, wherein said method comprises:

• (a) providing a planar substrate having thereon a multiplicity of terminal areas;
• (b) applying an electrical potential having a first electrical polarity to said terminal areas;
• (c) applying an electrical potential having a second electrical polarity to an electrical terminal immersed in a container of an electroplating solution;
• (d) exposing said substrate to said electroplating solution to permit the growth of said metallization bumps on said terminal areas;
• (e) controlling the growth of said metallization bumps in a predetermined region of said substrate by altering the metallic ion concentration of said electroplating solution in said predetermined region;
• (f) providing said container with an opening whose shape approximates that of said substrate;
• (g) positioning said substrate proximate to said container opening;
• (h) providing an inlet within said container for pumping said solution into said container, said solution exiting said container through said opening;
• wherein said metallic ion concentration of said electroplating solution is changed by:
• (i) in step (f) altering the size of said opening;
• (j) in step (g) altering the distance of said substrate from said container opening;
• and
• (k) in step (h) altering the flow rate of said solution through said opening.