Wet Etching

Wet Etching is an etching process that utilizes liquid chemicals or etchants to remove materials from the wafer, usually in specific patterns defined by photoresist masks on the wafer.  Materials not covered by these masks are 'etched away' by the chemicals while those covered by the masks are left almost intact.  These masks were deposited on the wafer in an earlier wafer fab step known as 'lithography.'

 A simple wet etching process may just consist of dissolution of the material to be removed in a liquid solvent, without changing the chemical nature of the dissolved material. In general, however, a wet etching process involves one or more chemical reactions that consume the original reactants and produce new species.