Wet Chemical and Plasma Etching
Etching is the process of removing portions of a thin film by chemical or physical processes. Wet chemical and plasma etching are two of the most common methods used in research and manufacturing. Advantage of wet chemical etching is the low damage, since there are no ions or energetic particles involved. Since the etching process is strictly a surface action, the atoms immediately below the surface will remain damage free. A large number of etch chemicals have been developed for different metals and dielectrics assuming silicon as the substrate and photoresists as the etch mask. Plasma etching is best understood from the perspective of chemical vapor deposition. The basic plasma etching system is almost identical to a plasma-enhanced chemical vapor deposition system. It consists of a vacuum chamber with a controlled gas in-flow rate and a throttled pumping rate to control the chamber pressure. Most etch processes are rarely performed with a single gas.