Homogeneous and sharp Si nanoprobe array fabricated on (111) silicon wafer

This work presents a novel fabrication method for homogeneous and sharp nanoprobe array on (111) silicon wafer. Utilizing the specific spatial structure of {111} planes and self-limiting procedure, the probe can be made with precisely controlled size requiring only a series of conventional semiconductor processes (dry etching of silicon by DRIE, anisotropic wet etching by potassium hydroxide solution and thermal-oxidation-based tip sharpening). The fabricated probe is composed of a pyramid-shaped base and a sharp tip. The diameter of the tip is less than 30 nm, with a vertex angle less than 18°.