Dry etching refers to the removal of material, typically a masked pattern of semiconductor material, by exposing the material to a bombardment of ions (usually a plasma of nitrogen, chlorine and boron trichloride) that dislodge portions of the material from the exposed surface. Unlike with many (but not all, see isotropic etching) of the wet chemical etchants used in wet etching, the dry etching process typically etches directionally or anisotropically. (http://www.thefreelibra...)