Hard mask free DRIE of crystalline Si nanobarrel with 6.7nm wall thickness and 50∶1 aspect ratio

Because of the unique mechanical and electrical properties, silicon was widely used in IC/MEMS devices for decades. However, it is difficult to fabricate high aspect ratio structures when the feature size scaling down to 7nm. In this paper, single crystal Si nano barrel with wall thickness 6.7nm and aspect ratio 50:1 was achieved by top-down process. The fabrication was carried out by Electron Beam Lithography (EBL) for patterning and DRIE for pattern transfer, utilizing photoresist as etching mask directly. To predict the barrel profile, a model of ion transportation was established. This tactic provides a potential arsenal for the next generation of 3D-IC and NEMS devices.