Simulation study of three-dimensional grayscale ice lithography on amorphous solid water for blazed gratings

Electron beam lithography (EBL) on amorphous solid water (ASW), termed as ice lithography (IL), has demonstrated promising capability in pattern transfer with unique advantages such as reduced proximity effect. So far, ice lithography for binary patterning has been proved a great success, however, application for three-dimensional (3D) profiling in nanoscale has still not been addressed to the best of our knowledge. This paper reports, for the first time, our progress in simulating study of three-dimensional ice lithography on ASW for linear blazed gratings, aiming to overcome the difficulty in replicating high quality blazed gratings with high diffraction efficiency. Systematic simulation of grayscale ice lithography for 3-D blazed grating templates with desired surface quality as the task was carried out, using Monte Carlo algorithm based on the measured contrast curves of ASW. For comparison, grayscale electron beam lithography on PMMA was also performed. The resultant profiles of blazed wavelengths around 1550 nm by grayscale IL show less flaws and higher diffraction efficiencies than by EBL. The successful simulation of 3D grayscale IL provides us with instructive guide for the fabrication of 3D nanostructures as a whole through the grayscale ice lithography on ASW.