3D Nanostructuring of hydrogen silsesquioxane resist by 100 keV electron beam lithography

The authors investigated the three-dimensional nanostructuring of hydrogen silsesquioxane (HSQ) resist by multiple-step 100 keV electron beam lithography. Consecutive overlay exposures were used to create two- and three-levels in high aspect ratio HSQ structures with lateral dimensions down to 30 nm and resist thicknesses of about 1 μm. The HSQ resist was developed by a high contrast solution and supercritically dried in a carbon dioxide environment after each exposure step. The three-dimensional HSQ patterning has potential applications in the fabrication of performance enhanced devices such as photonic crystals, nanoelectromechanical systems, and diffractive X-ray lenses.