Photolithographic Patterning of a Conductive Polymer Using a Polymeric Photoacid Generator and a Traceless Removable Group Horacio J. Salavagione,* a Marı ´a C. Miras, Cesar Barbero Departamento de Quı ´mica, Universidad Nacional de Rı ´o Cuarto, Agencia postal #3, 5800-Rı ´o Cuarto, Argentina Fax: þ34-965903537; E-mail: salavagione@ua.es Received: September 9, 2005; Accepted: October 18, 2005; DOI: 10.1002/marc.200500653 Keywords: conducting polymers; lithography; photoacid generator; traceless Introduction The fabrication of conductive patterns by chemical and photochemical means is of great importance in techno- logies such as printed board production and microelec- tronics. The increased use of conducting polymers (CPs) for electronic and optoelectronic applications [1,2] requires new patterning methods of CPs. [3] Holdcroft and co-workers [4] synthesized polythiophenes bearing pendant groups, which can be hydrolyzed by acids, to make them amenable to chemically amplified lithography. In previous work, [5] we developed a simple chemical lithographic process to produce conducting polyaniline (PANI) images using nitrosated PANI (PANI-NO) as a PANI precursor and hydrochloric acid as the hydrolyzing agent. In that pro- cedure the modifier functional group could be removed after the polymer was processed (a traceless functional group removal [6] ), and the resultant material then retained its intrinsic properties during processing. A similar proce- dure has later been used to pattern PANI from a tert- butyloxycarbonyl (t-BOC)-modified PANI film. [7] Technological applications of this lithographic method is limited by the use of strong acids, which can be harmful for some parts of the devices. To avoid this problem, litho- graphic patterning of PANI has been achieved using acid [7,8] or base [9] photogenerators, which could alter the solubility of the polymer by both changing its protonation state (doping–undoping) or cross-linking chains. [10] Fur- thermore, photoacid generators (PAGs) have been used as polymerization initiators. [11] Most PAGs are blended with the PANI precursor by dissolving both in the same solvent. Nevertheless, the available PAGs may give strong acids and residual sub- products, like free radical species, which frequently are not eliminated, and remain occluded in the polymeric films where they contribute to its deterioration. In addition, the PAG could diffuse during the process and thus generate distortion in the borders. Blends of poly(vinyl chloride) (PVC) with intrinsic con- ductive polymers (ICPs), such as PANI or polypyrrole, could Summary: In the present communication we describe a photolithographic method to produce polyaniline (PANI) patterns using PANI modified with a traceless removable functional group (nitrosated polyaniline, PANI-NO) and external inexpensive polymeric photoacid generators (poly (vinyl chloride), PVC). Therefore, residual sub-products created by irradiation of the plate do not remain occluded in the polymeric films. The borders of the patterns are better defined than in the case of chemical lithography using inorganic acids as the hydrolyzing agent. Macromol. Rapid Commun. 2006, 27, 26–30 ß 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 26 DOI: 10.1002/marc.200500653 Communication a Present address: University of Alicante, Departamento de Quı ´mica Fı ´sica e Instituto Universitario de Materiales, Apartado 99, 03080 Alicante, Spain.