An investigation is made of the plasma polymerization of fused polycyclic monomers containing a dioxy-ring that is fused to an aromatic ring. These molecules provide the basis for very efficient polymerization mechanisms in which only the dioxy-ring undergoes ring opening during the polymerization with the remaining part of the monomer remaining intact. XPS, ToF-SIMS, and IR are used to investigate the chemistry of the films produced by plasma polymerization of EDT, which contains a high content of the aromatic group. We find that the plasma-polymerized films of EDT contain intact thiophene groups with hydrogen in the position which is able to co-polymerize with thiophene derivatives polymerized by conventional oxidative polymerization, thereby forming a conducting thiophene polymer bonded to the substrate. The durability of the surface modification procedure is demonstrated by micropatterning of PEDT by a lithographic lift-off technique, where line-widths down to 1.25 m are obtained.