Simple method to measure the etching rate of monocrystalline silicon in KOH solution

A simple and low‐cost method is proposed to measure the etching rate of monocrystalline silicon in KOH solution with various pHs through atomic force microscopy. The native oxide on the silicon surface is applied as a mask film to achieve selective etching. A quadrate‐part area of the native oxide on silicon substrate surface is removed through the non‐destructive tribochemical removal of the SiO 2 microsphere. As a result, the fresh subsurface silicon is exposed and etched smoothly. The adjacent remaining native oxide is hardly etched by the KOH solution. After etching in KOH, a step forms at the boundary between the remaining native oxide layer and exposed silicon surface. The atomistic‐precision measurement of atomic force microscopy can detect a tiny etching depth of silicon, thereby acquiring the accurate etching rate in the KOH solution. This method provides a new and simple concept to measure the etching rate of materials in a suitable etchant and afford high‐precision measurement to the etching rate required in the design of a material etching process.