Fabrication of Periodic Nanostructure in Nanoimprint Process

In this paper nanoimprint molds with 50nm and 100nm feature size nanostructure were fabricated. The periodic pattern of a positive resist was formed on silicon wafer by electron beam lithography, and then the nanostructure of Si was etched using an inductively coupled plasma reactive ion etching (ICP-RIE) system. During the etching process, different ratio of C4F8gas was added to the original etching gases SF6/O2. By increasing the C4F8gas, the sidewall protection was improved. The C4F8gas also increased the etching resistance of the electron beam resist, and the nanoseale resist patterns were maintained through the etching process. The resist was removed after etching, and then the 50nm periodic nanostructure with aspect ratio 6 was obtained. To achieve nanoimprinting process with less damage, the possible sources of stresses resulting from the molding/demolding process, film solidification and thermomechanical mismatch during cooling were studied.