Advanced Trench Filling Process by Selective Copper Electrodeposition for Ultra Fine Printed Wiring Board Fabrication

A trench filling type process to fabricate ultra-fine pitch printed wiring boards was developed by combining nano-imprint lithography (NIL) and selective copper deposition. Copper was electorodeposited selectively inside the trenches fabricated in the dielectric layer by NIL process, without causing excess deposition on the surface. The selective deposition was realized by a novel electrodeposition bath employing Cyanine dye as an inhibiting additive. The recessed interconnections with 10 µm line and space dimension were successfully fabricated. The developed process shows significant advantages to the processes employing non- or less- selective deposition, which require planarization to remove excess copper deposited on the surface, and may potentially replace the state of the art semiadditive process.