A novel method to fabricate silicon nanoprobe array with ultra-sharp tip on (111) silicon wafer

In the work, a novel fabrication method for homogeneous and sharp nanoprobe array on (111) silicon wafer is presented. The specific spatial structure of {111} planes and the unique anisotropic etching mechanism on (111) wafer were utilized to form a size controllable funnel-neck structure. A highly downscaled size-reduction technology is developed for precise size control. Followed with a self-limiting oxidation procedure, sharp and long needles can be made with precise size control requiring only a series of conventional processes (dry etching of silicon by DRIE, anisotropic wet etching by potassium hydroxide solution and thermal-oxidation-based tip sharpening). The fabricated probe, whose tip’s diameter is less than 30 nm, can potentially have broad application to cell research.