Fabrication of sharp tips with high aspect ratio by surfactant-modified wet etching for the AFM probe

We use the surfactant-modified wet anisotropic etching, a promising micromachining technique we have recently focused on, to fabricate sharp silicon tips with high aspect ratio without additional sharpening by thermal oxidation. Because of the intriguing variation of etching characteristics in surfactant-added solutions as compared to traditional etchants, tips possessing a front angle of about 18° and a radius of curvature of less than 20 nm are created. The intermediate statuses are simulated by software and modeled. Moreover, integrated with silicon cantilevers, a new atomic force microscopy (AFM) probe is fabricated which has precisely controlled beam thickness, thus enabling the observation of a narrower part of the sample with steep sidewalls.