MODIFICATION OF ELECTRICAL-CONDUCTIVITY AND SURFACE-STRUCTURE IN POLYMERS USING ULTRAVIOLET-LASER RADIATION

Irradiation of most polymers with ultraviolet lasers results in perman ent changes in their surface morphology and electrical conductivity. U sing KrF (248 nm) excimer laser radiation, the electrical conductivity of polyimide (Kapton) and polybenzimidazole (PBI) has been increased by as much as sixteen orders of magnitude, obtaining values on the ord er of 10 OMEGA-1 cm-1. This laser-induced conductivity exhibits a thre shold both in fluence and in the number of laser shots and has a satur ation conductivity which is slightly fluence dependent. Periodic line structures with a period of 167 nm and linewidths varying from 30 to 1 00 nm have been produced in polyimide by direct ablation with a KrF la ser using an interferometric technique. This experiment establishes th e optics- and materials-dependent spatial resolution limits for laser ablation and for the modification of the electrical conductivity in po lymers. An array of sub-micron wires has been produced in polyimide, d emonstrating the ability to modify electrical conductivity in polymers with high spatial resolution.