New inductive rf discharge using an internal metal antenna

In conventional ICP (or TCP) reactors, a rf power is inductively coupled to an antenna placed outside a plasma vessel. Such an external coupling system is known to have several disadvantages. In order to avoid these disadvantages, a new internal coupling system has been developed in which a bare metal antenna is directly immersed in a plasma. thus forming a full metal reactor. This is accomplished by generating magnetic field lines around an antenna conductor, which effectively suppress the electron loss at the antenna and hence suppress the anomalous rise of plasma potential. Magnetic fields near the antenna are formed by superposing a dc current on a rf current along the antenna. This type of ICP enables rf discharges at rather low; pressures such as similar to 3 x 10(-4) Torr due to the magnetron effect. Other characteristics of internal metal antennas are also discussed.