Reactive-monolayer-assisted thermal nanoimprint lithography with a benzophenone-containing trimethoxysilane derivative for patterning thin chromium and copper films

Reactive-monolayer-assisted thermal nanoimprint lithography was applied for patterning thin films of chromium (Cr) and copper (Cu). The metal surfaces with the oxide layer were modified with a benzophenone-containing trimethoxysilane derivative to induce a surface graft reaction of the benzophenone moiety with poly(styrene) (PS) used for a resist polymer. A thin PS film was successfully prepared as a resist layer for wet etching on the modified metal surfaces by spin-coating, followed by exposure to ultraviolet light and annealing without dewetting the resist layer. The thin PS film could be patterned by thermal nanoimprinting involving a removal of the residual layer by exposure to UV/ozone. The patterned PS film worked as a resist mask for acidic aqueous wet etchants for Cr and Cu. We demonstrated that thin patterned films of Cr and Cu on micrometer scales could be fabricated by simple wet etching.