Thin electron beam defined hydrogen silsesquioxane spacers for vertical nanowire transistors

A method to fabricate inorganic vertical spacer layers with well-controlled thickness down to 40 nm using electron beam exposure is demonstrated. These spacers are suitable in vertical nanowire transistor configuration. As spacer material, the authors use hydrogen silsesquioxane (HSQ), a material with low permittivity and high durability. They show that the resulting HSQ thickness can be controlled by electron dose used and it also depend on the initial thickness of the HSQ layer. To achieve good reproducibility, the authors found it necessary to fully submerge the nanowires beneath the HSQ layer initially and that the thickness of HSQ before exposure needs to be determined. Finally, they introduce these steps in an existing transistor process and demonstrate vertical nanowire transistors with high performance. (C) 2014 American Vacuum Society.