Wet etching

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 at different rates in different directions. On wafers the most used etchant is KOH.