We demonstrated the fabrication of a densely packed InAs fins network for nanoelectronic applications. High crystalline quality GaSb/InAs layers have been grown directly on 300 mm nominal (0 0 1)-Si substrate. The InAs was then processed by etching step using a lithographic mask based on block copolymer to obtain sub-20 nm width fins. This block copolymer has been optimized to self-assemble into lamellar structure with a period of 30 nm, standing perpendicular to the substrate thanks to a neutral layer. STEM-HAADF characterization displays vertical sidewalls InAs fins with a width as low as 15 nm spaced by almost 10 nm. Early electrical characterizations exhibit a current flow through the connected fins.