Enabling backside processing for perforated microfluidic devices

In this work, we review various methods for surface protection of perforated microfluidic devices. Among these methods, applications of adhesive tape and polymer coating have shown fundamental limitations for preserving device integrity. It is also revealed that conventional temporary bonding process incorporating wafer carrier and temporary bonding material (TBM) poses a major risk to microchannels-based devices. Furthermore, three approaches are evaluated to improve effectiveness of removal of TBM. The first approach uses a solvent spray process, which shows significant TBM residues after extensive cleaning. The second approach employs a mechanical peeling process to remove the bulk of TBM followed by a short-wet cleaning. The third approach utilizes a dry film resist (DFR) as an intermediate layer between the TBM and perforated wafer surface, resulting in a more efficient cleaning process and complete removal of TBM residues.