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    Plasma Science Monday Sessions
       Session PS-MoP

Paper PS-MoP18
Electron Energy Control in an Inductively Coupled Plasma by Means of Induction Field Reversal

Monday, October 29, 2001, 5:30 pm, Room 134/135

Session: Plasma Diagnostics and Plasma-Surface Interactions Poster Session
Presenter: H. Shindo, Tokai University, Japan
Authors: H. Shindo, Tokai University, Japan
T. Urayama, ADTEC Plasma Technology CO., LTD, Japan
Y. Horiike, The University of Tokyo, Japan
S. Fujii, ADTEC Plasma Technology CO., LTD, Japan
Correspondent: Click to Email
In the deep submicron etching for ultra large-scale-integrated circuit (ULSI) processes, the development of low-pressure and high density plasma sources has been highly required. In these plasmas, however, several crucial problems have risen up in conjunction with electron energy. These are related to the fact that the electrons are prone to be excessively energetic in high density plasmas generated at low pressures. In this work, we studied electron energy control in an inductively coupled plasma by employing different azimuthal mode antenna. It is expected for electron energy to reduce at higher azimuthal mode antenna, because induction field is reversed with a shorter length. The experiments were carried out in an inductively coupled plasma (ICP) which was produced in a stainless-steel chamber of 350 mm in diameter by supplying the RF power of 13.56 MHz through the quartz window at one end. The three types of antenna were prepared.The electron temperature could be reduced by increasing the azimuthal mode number of one-turn antenna with no notable change in electron density. These effects were remarkable in low pressures below 10 mTorr, hence in a condition of longer electron mean free path. The mechanism for these behaviors is that the electron temperature at lower pressures depends on both the electron mean free path and the field reverse distance, as anticipated. The electron gains more energy with larger field reverse distance so long as the mean free path is same, and the electron mean free path is inversely proportional to the pressure.The RF magnetic field was also measured by a pick up coil, and its behavior was quite consistent with the electron energy, meaning that the electron energy change is not due to the capacitive effect. It was concluded that the induction field reverse distance in conjunction with electron free path was essential in electron energy control.