Title:
3D EBL with organic ice resist

Abstract:
A novel technique, 3D Ice lithography, for printing 3D structures at the nanoscale will be presented. The presentation will focus on its potential as a new versatile lithographic tool. Organic vapours are condensed into thin layers of ice on the surface of a cold substrate. Each layer is exposed to an electron beam cross-linking the molecules of the ice layer in a pattern defined by the electron beam. Complex 3D structures of cross-linked material can thus be created by varying the beam pattern from layer to layer. After all layers have been processed, the substrate is heated to a temperature high enough to cause sublimation of the unexposed material, so only the printed 3D lithographic structure is being left on the substrate, leading to an entire spin- and development-free lithography process. All processing requires only a single custom instrument. We report the design, material choice, implementation and operation of this apparatus. It is based on a scanning electron microscope fitted with an electron beam control system like the ones normally used for electron beam lithography. The microscope is also equipped with a gas injection system, a liquid nitrogen-cooled cryostage, a temperature control system, and a load-lock. All in all, a 2-in-1 solution being both a unique, high-resolution 3D printer or lithographic tool and, at the same time, also an electron microscope.