Plasma Etching
Plasma etching uses a gas that is subjected to an intense electric field to generate the plasma state of
matter. The electric field is produced with coils that are wrapped around the chamber and exposed to a
high level RF source. There are two different versions of this type of etching based on the shape of the
chamber used. One consists of a barrel type chamber where the wafers are placed sitting up while the gas
is flowed over the wafers and out through an exhaust pipe. The second process uses a parallel plate
reactor. There are two plates that are used to give the gas the electric field rather than the coil that is
wrapped around the barrel chamber. In plasma form, the gases used are very reactive, providing effective
etching of the exposed surface. Plasma etching provides good critical geometry but the wafer can be
damaged from the RF radiation.
Reactive Ion Etching
This method works at a lower pressure and uses a combined physical and chemical method to etch the
wafer.