Decal Transfer Lithography

Abstract

A new soft-lithographic method for micropatterning polymeric resists, Decal Transfer Lithography (DTL), is described. This technique is based on the adhesive transfer of elastomeric decal patterns via the engineered adhesion and release properties of a compliant poly(dimethylsiloxane) (PDMS) patterning tool. This procedure is capable of transferring micron to sub-micron-sized features with high fidelity over large substrate areas in both open and closed forms, negative and positive image contrasts. Methods are introduced to promote adhesion of PDMS to noble metals using either of two methods: self-assembling monolayers (SAMs) or silicon dioxide capping layers. A novel UV/Ozone (UVO) mask was developed, which allows the photopatterning of UVO modifications of polymer surfaces. This modification in turn enables the direct photoinitiated patterning of resist patterns transferred by the soft-lithographic DTL method Photodefined-Cohesive Mechanical Failure (P-CMF), which fuses the design rules of the contact based adhesive transfer of PDMS in DTL with those of photolithography. The second, so-called Spartacus method, transfers the design rules of photolithography directly onto PDMS surfaces, enabling a photodefined adhesive transfer of PDMS films onto silicon oxide surfaces. The most significant advance embodied in the DTL method, however, is that is offers useful new capabilities for the design and fabrication of patterns of non-planar surfaces, 3D microfluidic assemblies, and microreactors.