As mentioned previously, dry etching and wet etching are the two main types of etching. Wet etching includes multiple chemical reactions.

It involves the following three steps:

1. Diffusion of the liquid etchant to the material (that needs to be etched)
2. Reaction between the liquid etchant and the material
3. Desorption of the byproducts from the surface

An example of dry etching is plasma etching. Plasma etching in plasma etching systems involves the following six steps:

1. Production of the reactive species in a plasma
2. Diffusion of the reactive species onto the material’s surface
3. Adsorption of the reactive species onto the material’s surface
4. Reaction (chemical) between reactive species and material that forms volatile byproducts
5. Desorption of the volatile byproducts
6. Diffusion of these byproducts into the bulk gas and expelled through vacuum system