Abstract The original meaning of ‘etching’ is ‘to eat’; the process of removing something from an object. Moreover, it is impressive that another original meaning of it is ‘to feed’. In fact, reactive ion etching (RIE) consists of two processes; ‘to eat’ and ‘to feed’. The physical process of etching is to remove particles from a solid surface by the colliding energy of ions which is converted into thermal, chemical, or kinetic energy. The mechanisms of etching can be classified by forms of energy exchange: chemical and physical. The etched pattern can be classified into two types: anisotropic (directional) etching and isotropic (indirectional) etching. When thermal and chemical energies are transformed in the reaction, then indirectional etching will be processed. Liquid chemical etching is a typical example of indirectional etching.