Effect of a photo-crosslinkable chemisorbed monolayer on thermal nanoimprinting of a poly(styrene) thin film on a gold substrate

Figure 1 shows SEM images of a poly(styrene) thin film on a gold substrate after thermal nanoimprinting. When a bare gold substrate without a monolayer was used, most of a patterned PSt layer adhered to a silicon mold modified with a fluoro-containing stripper as shown in Figure 1a. Similar results were obtained in the case of a gold substrate with the photo-crosslinkable chemisorbed monolayer as shown in Figure lb. When the PSt layer on a gold substrate with the photo-crosslinkable chemisorbed monolayer was irradiated with a ultraviolet light at 365 nm before thermal nanoimprinting, interestingly adhesion of patterned PSt layers to a silicon mold was suppressed as shown in Figure 1c. These results clearly suggested that a photo-crosslinking reaction of the benzophenone moiety with PSt proceeded, which strengthened adhesion of a PSt layer to a gold substrate surface.