Patterning of Conducting Polymers Using UV Lithography: The in-Situ Polymerization Approach

We report on the in situ polymerization of 3T with CU(ClO4)(2) inside several host polymers such as Novolak-based negative tone photoresist, polystyrene (PS), poly(4-vinylphenol) (P4VP), poly(methyl. methacrylate) (PMMA), and poly(4-vinylphenol)-co-(methyl methacrylate) (P4VP-co-MMA) to form an interpenetrating Polymer, network (IPN). Conducting IPN films in the order of 10(-4)-150 S/cm are obtained depending on the specific IPN composition., Moreover, the convenience of this synthetic approach has been demonstrated using a commercially available negative tone photoresist based on Novolak as a host polymer. Novolak photoresist was properly formulated with 3T and Cu(ClO4)(2) to preserve.,as far as possible the negative lithographic characteristics of Novolak-based photoresist and generate conductive micropatterns by means of UV lithography. The CP is in situ synthesized into the Novolak matrix by a postbake after the lithography process (exposure development). The electrical conductivity of the patterned film is 10(-2) S/cm. We accurately patterned three-different types of microstructures with different resolutions: interdigitated structures with a width of 100 mu m, 200 mu m side squares, and a 20 mu m wide cross. We believe this synthetic approach is of potential application to modify the conductivity of numerous insulating polymers while preserving their physical and chemical properties.