Offset printing of liquid microstructures for high resolution lithography

We have investigated the direct printing of polymer solutions from a chemically patterned stamp onto a hydrophilic target substrate as a new high-throughput alternative to optical lithography. The patterns on the stamp, which are typically in the micron size range, define regions of alternating wettability. They are produced by patterning a hydrophobic self-assembled monolayer previously deposited onto a hydrophilic surface, typically a glass slide or silicon wafer with a natural oxide coating. Polar liquids or aqueous polymeric solutions are then deposited only onto the hydrophilic surface patterns by dip-coating the stamp in a liquid reservoir. The deposited film thickness depends critically on the speed of withdrawal and the feature size and shape. For vertically oriented hydrophilic stripes dipped in a reservoir containing a polar liquid, we have developed a theoretical model whose prediction for the maximum deposited film thickness agrees exceptionally well with experimental measurements. After deposition, the wetted stamp is pressed against a target substrate by means of a motion controlled press. In this way we have so far printed 5µm wide polyethylene oxide lines onto a silicon wafer.