Improved pattern transfer in soft lithography using composite stamps

Composite stamps composed of two layers-a stiff layer supported by a flexible layer-extend the capabilities of soft lithography to the generation of 50-100-nm features. The preparation of these stamps was adapted from a procedure originally developed by Schmid et al. (Macromolecules 2000, 33, 3042) for microcontact printing. This paper demonstrates how pattern transfer using other soft lithographic techniques-micromolding in capillaries, microtransfer molding, and phase-shifting lithography-can be improved using two-layer stamps relative to stamps made of Sylgard 184 poly(dimethylsiloxane).