Droplet spreading nanoimprinting method for micro-/nano-fabrication

This paper proposes an innovative nanoimprinting method that features imprinting a single droplet of resist and spreading it from center to edge to fully cover a full wafer substrate. Important advantages of this type of nanoimprinting include avoiding air bubble trapping, forming conformal mold/substrate contact, minimizing residual layer thickness, and saving the amount of resist being used. It also makes the demolding process much easier and more successful. To realize this nanoimprinting method, an imprinting tool is designed, constructed, and experimentally tested, and three key components are developed. First of all, a soft mold is integrated into a dovetailed metal ring so that it can be fixed at its edge and deformed by external force. Secondly, two independent loading mechanism are installed so that a soft mold can be initially deformed to form a point contact with a substrate and then followed by imprinting process. Finally, an elastomer cushion pad with a pre-designed convex surface profile is used to convert the loading force into a specific distributed contact pressure which can drive the resist flow. Nanoimprinting experiments have been carried out for pattering micro-scaled and nano-scaled structures on 4″ glass wafers. Excellent imprinting results are observed. The potentials and future perspectives of the proposed nanoimprint system will be addressed.