Wet etching is the removal of material by immersing the wafer in a liquid bath of chemical etchant.

There are two kinds of wet etching etchants, isotropic etchants and anisotropic etchants:

- Isotropic etchants attack the material being etched at the same rate in all directions.

- Anisotropic etchants attack the silicon wafer ate different rates in different directions, on wavers the most used etchant is KOH.