Limiting roughness in anisotropic etching

An experimental study is made to establish if the roughness of the etched surface attains a saturation value during the KOH etching of silicon, as predicted by the atomic scale simulators. We showed there is a stable saturation roughness specific to the orientation of the wafer, but much greater than the values predicted by the simulators. The same saturation roughness is reached independent on the initial roughness of the surface. Surfactants dissolved in small concentrations in the etchant were shown to reduce drastically the saturation value of the roughness and rise the etching rates, without affecting noticeable the anisotropy diagrams.