A small cantilever probe for high speed AFM imaging in water has been developed. It is a rectangular cantilever, so‐called beak‐like cantilever, made of silicon‐nitride with dimensions of about 10 &mgr;m × 2 &mgr;m × 0.13 &mgr;m. By applying oxide‐sharpening technique for silicon nitride probe apexes, the triangular apexes that were shaped by photo‐lithography, were further sharpened and terminated into one point. An average radius of curvature of 18.4 nm was achieved. This novel sharpening technique is useful for the fabrication of small cantilevers when low cost is required. The typical resonant frequency of the small cantilevers was 1.4 MHz in air and the estimated spring constant was 0.2 N/m. Immersing the cantilevers in water, the resonant frequency dropped by a factor of three to five. © 2003 American Institute of Physics