ABSTRACT
The Potassium hydroxide (KOH)-based solution has been used for decades for the purpose of anisotropic etching of single-crystal silicon. Etching of single-crystal materials such as quartz and silicon has been investigated for decades for industrial purposes. The etch rate anisotropy varies depending on KOH concentration, temperature, and some additives, including surfactant and metallic ions. In anisotropic wet etching using KOH as well as tetramethylammonium hydroxide solutions, the etch rate of silicon strongly depends on etching temperature. Roughness of the etched surfaces is comparable with the roughness obtained in KOH solutions containing isopropanol, though the sizes of isopropyl alcohol and diol molecules differ from each other significantly. In terms of silicon etching, the range with a very high alcohol concentration is not very much interesting since such concentrations are impossible to achieve in KOH–alcohol solutions due to limited solubility of alcohols in KOH.
