Etching

 

Etching chemically removes layers from the surface of a wafer during manufacturing. Dry etching refers to the removal of a masked pattern on the wafer by exposing the material to a variety of ions (usually a plasma of nitrogen, chlorine and boron trichloride), that dislodge portions of the material from the exposed surface.

 

Unlike with many of the wet chemical etchants used in wet etching, the dry etching process typically etches directionally or anisotropically. Some wet etchants etch crystalline materials at very different rates depending upon which crystal face is exposed. In single-crystal materials (e.g. silicon wafers), this effect can allow very high anisotropy.