AVS 52nd International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS-ThA

Paper PS-ThA1
Characteristics of Large-diameter Plasma using a Radial Line Slot Antenna

Thursday, November 3, 2005, 2:00 pm, Room 304

Session: Plasma Sources and Equipment
Presenter: C. Tian, Tokyo Electron LTD., Japan
Authors: C. Tian, Tokyo Electron LTD., Japan
T. Nozawa, Tokyo Electron LTD., Japan
K. Ishibasi, Tokyo Electron LTD., Japan
H. Kameyama, Tokyo Electron LTD., Japan
T. Morimoto, Tokyo Electron LTD., Japan
Correspondent: Click to Email
A radial line slot antenna (RLSA) for surface-wave-plasma at 2.45GHz is a promising candidate with respect to increased process requirements for the large-diameter plasma as well as the gas dissociation control and free plasma damage. Characteristics of such a kind of plasma have been studied by both direct plasma probe measurements and numerical simulations. The discharge chamber is 40 cm in diameter and 30 cm in depth with a quartz glass window 3 cm thick on the top. A custom inductively coupled plasma (ICP) is also evaluated for comparison by replacing the RLSA with an RF coil mounted on the top window. Some unique characteristics of RLSA has been found by both radial and vertical direction plasma measurements, which are: (1) the electron temperature of RLSA is about 0.9eV-1.2eV low under the various power input and gas pressure conditions, half as many as the ICPs; (2) the main plasma generation area of RLSA is limited in the plasma surface just below the quartz glass window, while the ICP involve a much wider range; (3) the electron energy distribution functions (EEDFs) of RLSA plasma show few high energy electrons existing in the plasma diffusion area as compare to the ICPs. Numerical simulations are implemented to reveal the more essential difference in plasma generation between the RLSA and the ICP, where the superiority of RLSA plasma has been confirmed. The critical uniformity of the radial plasma distribution has been evaluated by the view of RLSA optimization. Optimal design of the slot pattern and the top glass window shape are effective in keeping the high plasma uniformity robustly from various processing conditions. Numerical analysis of microwave propagation helps to achieve the RLSA optimal design. The features of high plasma uniformity and low electron temperature lead to free plasma damage in our associated etching process.