Dry etching is known as plasma dry etching is the process of removing materials from the surface of another material. This process occurred by collision of excited ions with the material and remove it without using any liquid chemicals or etchants. It is more directional or anisotropic than wet etching process helps reduce sloppy etching and possibly poor electrical reliability.     

Figure 1: Fabricating holograms with reactive ion etching

Dry etching is currently used in printed circuit board and semiconductor fabrication processes due to its unique ability over wet etch to do anisotropic etching (removal of material) to create high aspect ratio structures (e.g., deep holes or capacitor trenches). Otherwise, this process is completely safe and an environmentally friendly process available. Dry etching is also suitable for large scale production, while still having reasonably sized.