Electroplated Copper Filling of High Aspect Ratio Blind Vias in High Density Interconnect Printed Wiring Boards and Silicon Wafers

摘要

Filling blind vias with electroplated copper is becoming a popular alternative to conductive paste plugging. This paper investigates a method of filling blind vias using a copper electroplating technique. A CO_2/UV laser was used to form high aspect ratio blind vias in printed wiring boards (PWB'S) and a Deep Reactive Ion Etcher (DRIE) was used to form blind vias in silicon wafers (SOI). An initial copper seed layer was deposited in the PWB vias using an electroless plating process; whereas, the silicon wafer's initial copper seed layer was deposited using a vacuum sputtering technique. The test substrate's blind vias were then filled using a copper electroplating process. Process variables examined were rectification, pretreatment processes, solution flow and current density. Via fill uniformity was evaluated by microsection and scanning electron microscope measurement techniques.