Handbook of Silicon Based MEMS Materials and Technologies

24.1. Basic Description of Anisotropic Etching: Faceting

Wet etching consists of the use of an alkaline or acidic solution (the etchant) to chemically remove material from the surface of a sample. Etching has its origins in an artistic technique, developed in the fifteenth century, consisting of covering a metal surface—such as that of a knight’s armor—with a waxy material, removing part of the wax to create the desired decorative pattern, and finally dipping the surface in an acid solution to chemically remove the metal from the wax-unprotected areas, thus transferring the pattern to the metal. In addition to metals, etching can also be used to create patterns in many other materials.

In the area of micro/nano electro-mechanical systems (MEMS ...