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 paperinvestigates a method of filling blind vias using a copper electroplating technique. A CO2/UV laser was used to form highaspect ratio blind vias in printed wiring boards (PWB'S) and a Deep Reactive Ion Etcher (DRIE) was used to form blind viasin 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 testsubstrate'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 scanningelectron microscope measurement techniques.