A new type of polymer Langmuir-Blodgett (LB) films composed of N-dodecylacrylamide (DDA), which is known to form a stable monolayer, and a photodegradable monomer, tert-butyl-4-vinylphenyl carbonate (tBVPC), were prepared with the aim of developing a novel thin-film positive-tone resist. The copolymer [p(DDA-tBVPC)] could form a stable, condensed monolayer, even at high compositions of tBVPC (53 mol.%), and the monolayer could be successfully transferred onto solid supports, such as quartz, glass, and silicon slides, giving Y-type uniform LB films. The polymer LB films could be efficiently decomposed by deep UV irradiation, and after development with alkaline solution, a clear positive tone pattern with a line width of 0.75 mum, which is the highest resolution of the photomask employed, was visible. Moreover, it was found that these copolymer LB films with nm thickness show high resistance performance to an etching process. These fascinating features of the copolymer LB films show them to be potential candidates as key materials in nano-lithography.