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
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 O2/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.