Three-dimensional resist-coating technique and nanopatterning on a cube using electron-beam lithography and etching

A new resist-coating technique for three-dimensional substrates keeps a substrate in a quasi-static ambient of very fine mist of resist solution, so that a resist can be uniformly coated on each face of the substrate. We found that the temperature of the substrate has to be carefully controlled to obtain a smooth resist surface. A polymethylmethacrylate resist was coated with good uniformity on an oxidized Si cube, and patterns delineated on different faces by electron-beam lithography were similar. The resolution was confirmed to be 50 nm or less by observing dense line patterns etched in the oxide film on the cube.