Low-energy electron-beam lithography of hydrogen silsesquioxane

Low-energy electron-beam lithography using hydrogen silsesquioxane (HSQ) as a negative electron resist has been investigated in the energy range between 2 and 20 keV. It is found that the required electron dose is drastically reduced at low electron energies and the density of the pattern strongly depends on the concentration of the developer and exposure energy at low keV region. With the tetramethyl ammonium hydroxide (TMAH) developer at concentration of 2.5%, we achieved 12 nm lines of 50 nm period grating with 50 nm thickness of HSQ at 10 keV.