Formation mechanism of periodic wrinkles around trimmed nanoimprint resist masks studied by surface analyses

Abstract We performed surface analyses of UV-cured films of a bisphenol A-based dimethacrylate resin by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry to understand the formation mechanisms for different resist shapes of wrinkled and dome imprint masks via oxygen reactive ion etching (O 2 RIE) and UV/ozone exposure, respectively, in trimming to decrease the diameters of resist masks for ultraviolet nanoimprint lithography. O 2 RIE generated a carbon-rich and oxygen-poor layer near the film surface owing to preferential oxidation of aliphatic hydrocarbons by hydrogen abstraction. In contrast, UV/ozone exposure generated an oxygen-rich outermost layer on a carbon-rich and oxygen-poor layer. The formation of the outermost layer was attributed to the photooxidation and ozonization of the aromatic hydrocarbon rings, whereas the underlying layer arose from the hydrogen abstraction of aliphatic hydrocarbons by atomic oxygen. The formation of bilayers suggests that the O 2 RIE caused buckling instability and generated wrinkles around the resist masks.