New Method of Photopatterning with LB Films Based on a Chemically Amplified Mechanism

A new approach to introducing a photoacid generator( PAG) into Langmuir-Blodgett( LB) films to draw photopatterns as a lithographic process is described here. The chemically amplified positive-tone resist system used here consists of two components: a copolymer, poly ( dodecrylacrylamide-co-4-t-butyloxylvinyl-phenylcarbonate) [P(DDA-t-BVPC53)] and a PAG, tri(2,3-dibromopropyl) isocyanurate(TDBPIC). In the two-component system, the acid generated by the PAG catalyzes the deprotection reaction of P(DDA-t-BVPC53), to remove the tert-butoxycarbonyl group(t-BOC) in the exposed region during the postexposure baking process, thus rendering the exposed region soluble to alkaline aqueous solvents to form a positive tone. Photolithographic properties of the LB films have been evaluated. The patterns can be resolved with a resolution of 1 μm line width by UV irradiation, followed by development with an alkaline solution. The LB films can be used to generate etched gold relief images on a glass substrate via an aqueous iodide, like ammonium iodide, in alcohol / water as the etchant. The etch resistance of such LB films is sufficiently good, allowing patterning of a gold film suitable for photomask fabrication.