Abstract: A method for producing a silicon nanosensor integrated with advanced complementary metal oxide semiconductor (CMOS) logic circuit having gate length (Lg) of less than 0.25 ?m, comprising the steps of: allocating a silicon nanosensor region and a CMOS logic circuit region on one bulk silicon substrate; forming silicon nanowires at the allocated nanosensor region while shielding the CMOS logic circuit region; applying a layer of protecting hardmask on the substrate such that the hardmask acts as an extra protection layer to the nanosensor region while acting as a hardmask for CMOS logic circuit formation process thereinafter; subjecting the substrate to selective etching to form trenches, filling the trenches with silicon oxide and subjecting the substrate to chemical mechanical planarization; and removing the hardmask from the substrate in a region-by-region manner, in which the nanosensor region remains unexposed while removing hardmark from the CMOS logic circuit region, and vice versa.