All-wet TSV filling with highly adhesive displacement plated Cu seed layer

For realizing high aspect ratio TSV with a low cost, the all-wet process using electroless barrier and seed layers prior to Cu electroplated fill is one of the key technology. However, improvement of adhesion property of electroless plated Cu seed layers on the barrier layer has been intensively required. In this study, we studied displacement plating of Cu on electroless CoWB barrier layer in an acidic bath. It is confirmed that the displacement plated Cu film has a high adhesion strength which is enough to pass CMP process.