A Simple Method for Fabrication of Self‐sharpened Silicon Tips for Atomic Force Microscopy Applications

Abstract

A simple and high yield method is presented for the bulk generation of atomic force microscopy (AFM) probes with self‐sharpened silicon tips. The experimental setup includes a controlled chemical etching environment at a constant temperature with continuous recirculation and filtration. A KOH solution is considered cost‐effective as the etchant and stabilized to the required concentration (55%, v/v) and temperature (40 °C), so as to provide an etch rate of 40 nm min−1 and yield a smooth etch profile. A high density of silicon tips is fabricated, with yield up to 90%, and a consistent tip radius of ≈12.73 ± 1.51 nm. These tips can be successfully integrated with AFM cantilevers, resulting in AFM probes. Further, such AFM‐probes are well characterized using laser Doppler vibrometry and scanning electron microscopy. The result shows a resonance frequency of 1.2–1.4 MHz and a high‐quality factor of ≈708.8. In addition, the AFM probes produced images are comparable in quality to those obtained from commercially available probes.

Applications of AFM in Membrane Characterization and Fouling Analysis

“…This blunting issue often requires additional steps such as thermal oxidation or focused ion beam (FIB) milling to sharpen the tip, but these steps can increase the overall technical costs. 93 Rudrappa et al 94 addressed this challenge by optimizing the conventional KOH wet etching technique. They achieved self-sharpening of the probe tip by using an extremely low etching rate and circular mask etching.…”

“…In many existing methods for manufacturing high aspect ratio probes, besides the aforementioned wet etching of silicon techniques, common approaches include dry etching or a combination of dry and wet etching, FIB milling, − and electron beam-induced deposition (EBID) . While wet etching offers cost advantages, KOH etching is highly dependent on crystal orientation and demands strict mask alignment; HF: HNO 3 : CH 3 COOH etching struggles to maintain a stable etching rate .…”