Chemical dry etching (also called vapor phase etching) does not use liquid chemicals or etchants.

This process involves a chemical reaction between etchant gases to attack the silicon surface.

The chemical dry etching process is usually isotropic and exhibits high selectively.

Anisotropic dry etching has the ability to etch with finer resolution and higher aspect ratio than isotropic etching.

Due to the directional nature of dry etching, undercutting can be avoided.

Some of the ions that are used in chemical dry etching is tetrafluoromethane $(CH_4)$, sulfur hexafluoride $(SF_6)$, nitrogen trifluoride $(NF_3)$ , chlorine gas $(Cl_2)$ , or fluorine $(F_2)$.