Photopatterning Based on a Chemically Amplified Mechanism Nano-Sheet Films

Abstract

In the paper, an approach for introducing a photoacid generator (PAG) into Langmuir- Blodgett (LB) films to draw photopatterns is described. The chemically amplified positive-tone resist system used here consisted of two components: a copolymer, poly(iso-pentylmethacrylamide- co-4-t-butyloxylvinylphenylcarbonate) [poly(iPMA-t-BVPC39)] and a photoacid generator (PAG), tri(2,3-dibrompropyl)iso-cyanvrate (TDBPIC). In the two-component system, the acid generated by the photoacid generator (PAG) catalyzes the deprotection reaction of poly(iPMA-t-BVPC39) to re- move the tert-butoxycarbonyl group (t-BOC) in the exposed region during the post exposure baking process, thus rendering the exposure region soluble to alkali aqueous to form a positive tone. Phhot- olithographic 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 alkali solution. Quantum yield is determined to be 0.065 and catalytic chain length is also calculated to be 2460. The LB films used above can be used to generate etched gold patterns on a glass substrate using an aqueous iodide, 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.