Inductively Coupled Plasma – Reactive Ion Etching (ICP-RIE) is a dry etch technique for removing material with the use of a chemically reactive plasma. The ICP part creates a plasma with a high ion density, while the RIE part creates a bias voltage at the substrate accelerating the reactive ions towards the substrate. At the substrate the ions will chemically react with the substrate material and etch away the material. Depending on the composition of the etch gas, the etch is more chemically or more physically. Materials that can be etched include materials like AlGaN, Al2O3, Al and Cr.