A material removal process by means of chemical corrosion.
Etching, either isotropic etching or anisotropic etching, removes
part of material in a corrosive environment of either gas or liquid phase, sometimes assisted with
electric energy (electrochemical etching). In the field of micromachining technology, anisotropic
etching is popular. Examples are application of potassium hydroxide (KOH) or ethylene diamine
pyrocatechol (EDP) to single crystal silicon, where the (111) crystal plane is etched away slower
than other crystal planes, leaving a three-dimensional structure consisting of the (111) crystal