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 PDMSpatterns on electronic material substrates using decal transfer lithography DTL in conjunction withreactive ion-beam etching RIE. We validate the use of this unconventional polymeric system as asuitable resist material for fabricating Si-based microelectronic devices. In this process, an O2/CF4gas mixture was used to etch a supporting PDMS thin film that resides atop a closed-form decalpolymer to reveal conventional resist structures. These structures provide an effective latent imagethat, in turn, provides for an extension of soft lithography as a form of multilayer lithography—oneyielding submicron structures similar to those obtained from the conventional photochemicalmethods used to prepare such resists. This combined DTL/RIE patterning procedure was found tobe compatible with commercially available planarization layers and provides a direct means forpreparing high aspect ratio resist features. We illustrate the applicability of soft lithography as ameans for fabricating electronic devices by using it to prepare model silicon-based thin-filmtransistors exploiting silicon-on-insulator wafer technology.