Boundary slip measurement and mechanism analysis in ultraviolet nanoimprint lithography of subwavelength moth-eye nanostructure

摘要

Subwavelength moth-eye nanostructure has been commonly used to reduce the surface reflection of optoelectronic devices, such as liquid crystal display, solar cell, image sensor, etc. Among various fabrication processes, the ultraviolet nanoimprint lithography (UV-NIL) technique combined with anodic aluminum oxide (AAO) mold provides an effective way for high-precision and high-efficiency fabrication of moth-eye nanostructure. To obtain high-precision moth-eye nanostructure, accurate analysis of UV-curing resin filling process into nanoscale AAO mold is necessary. In this research, the boundary slip phenomenon in nanoscale flow was investigated using atomic force microscope (AFM) method and it was found that boundary slip could produce a significant effect on nanoscale flow. Besides, the slip law on rough surfaces was further investigated. It was found the slip length reduced from 23.7 nm to 12.7 nm as roughness Ra increased from 0.47 nm to 3.18 nm, indicating that the roughness suppressed the slip motion. Moreover, the physical mechanism of boundary slip was also revealed, that was, the fluid properties and wettability caused intrinsic slip motion while the roughness could suppress intrinsic slip motion due to enhancement of internal viscous dissipation loss. The research could provide guidance for a more accurate understanding of boundary slip in nanoscale flow and high-precision fabrication of subwavelength moth-eye nanostructure.