Micron and submicron patterning of polydimethylsiloxane resists on electronic materials by decal transfer lithography and reactive ion-beam etching: Application to the fabrication of high-mobility, thin-film transistors

Abstract

We describe a technique for fabricating micron and submicron-sized polydimethylsiloxane (PDMS) patterns on electronic material substrates using decal transfer lithography (DTL) in conjunction with reactive ion-beam etching (RIE). We validate the use of this unconventional polymeric system as a suitable resist material for fabricating Si-based microelectronic devices. In this process, an O-2/CF4 gas mixture was used to etch a supporting PDMS thin film that resides atop a closed-form decal polymer to reveal conventional resist structures. These structures provide an effective latent image that, in turn, provides for an extension of soft lithography as a form of multilayer lithography-one yielding submicron structures similar to those obtained from the conventional photochemical methods used to prepare such resists. This combined DTL/RIE patterning procedure was found to be compatible with commercially available planarization layers and provides a direct means for preparing high aspect ratio resist features. We illustrate the applicability of soft lithography as a means for fabricating electronic devices by using it to prepare model silicon-based thin-film transistors exploiting silicon-on-insulator wafer technology.