Reactive Ion Etch

a technique whereby radio frequency radiation is coupled into a low pressure gas to ionize the gas producing disassociation of the gas molecules into more reactive specie, and the substrate being etched is biased to induce ion bombardment. Compounds containing carbon (C) and halogens such as, fluorine (F), chlorine (Cl) or Bromine (Br) are typically used as gases. When the compounds disassociate in the plasma, both highly reactive halogen atoms or halogen compounds, and polymers that may deposit on the substrate blocking the highly reactive species are generated. Ions accelerated towards the substrate being etched by the applied or induced bias remove polymers on substrate surfaces oriented normal to the direction of ion motion, polymers coat substrate surfaces that are oriented parallel to the ion motion and block etching of those surfaces. Ion bombardment may also activate or accelerate chemical etching reactions. RIE therefore has the capability to etch surfaces normal to the direction of ion motion at a higher relative rate and surfaces parallel to the ion motion at a lower relative rate resulting in anisotropic etching. Typical RIE conditions are low pressure, low ionization levels and high ion energies relative to other dry etch techniques.

see Reactive Ion Etch.