The Magnetic frequecny dependency of enhanced inductively coupled plasma

초록

Inductively Coupled Plasma(ICP) has a several merits, such as high density at low pressure at cheap price, simplicity, and good expandability. However, further efforts to improve plasma density and selectivity were hampered by some limitations; the power is transferred from the electric fields to plasma within a very short skin depth layer, and it is hard to control the ion energy, electron temperature, and ion/radical ratio. To improve the limitation of ICP, various solutions are proposed, such as new type of rf antenna, Faraday shield, applying the magnetic field and etc. Specially, the magnetization characteristics of plasma are studied most important. Recently, a novel method proposed by us, named as `Enhanced-ICP � (E-ICP) using periodic weak axial magnetic field added to a normal ICP source, has shown great improvement in etch characteristics. The physical origin of these good characteristics has not been known yet clearly. In this paper, we analyzed the plasma characteristics of E-ICP by the fast-operation technique of Langmuir probe and optical emission spectroscope. The periodic variation of ion density and the electron density are shown clearly in this measurement, and the effective electron temperature shows similar behavior. It is quite interesting to compare these characteristics to that of the pulsed plasma technique. The evidences of controlling plasma characteristics with magnetization frequency will be reported also. Furthermore, simple theoretical analysis for E-ICP is carried out as a stepping stone of further discussion.