AVS 57th International Symposium & Exhibition
    Plasma Science and Technology Tuesday Sessions
       Session PS-TuP

Paper PS-TuP22
2m Long-Linear Plasma Production by Microwave in a Narrowed Rectangular Waveguide with a Long Slot Antenna

Tuesday, October 19, 2010, 6:00 pm, Room Southwest Exhibit Hall

Session: Plasma Science and Technology Poster Session
Presenter: H. Shindo, Tokai University, Japan
Authors: H. Shindo, Tokai University, Japan
Y. Kimura, Tokai University, Japan
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Long line-shaped plasmas are inevitable in material processing in manufacturing industries, such as solar cell film CVD, flat panel displays (FPDs), and various surface modification of large-area thin films. In this work, a newly proposed method of large-scaled line plasma production is studied. In this method, microwave power of frequency of 2.45 GHz in a narrowed and flattened rectangular waveguide is employed to produce a long uniform line plasma. Since the width of waveguide is very close to the cutoff condition, the wavelength of microwave inside the guide is very much lengthened, providing a condition of long line high density plasma with a great uniformity.

The narrowed rectangular wave-guide of 1.0 and 2.0 m in length and 5mm in height were prepared and the width of the waveguide is 62.0 to 61.5 mm which is very closed to the cut-off condition. The waveguide has a long slot on the top surface to launch the micro-wave into the discharge plasma chamber of 1.0 and 2.0 m in length. At the end of wave guide, a short plunger was quipped to adjust the phase of the standing microwave, hence the uniformity of the plasma thus produced. The plasmas of Ar at the pressures of 100 to 500 mTorr were produced by employing an extremely long microwave wavelength. The plasma thus produced was three-dimensionally measured by a Langmuir probe.

The axial profile of electron density in the plasma thus produced was quite flat and as the microwave power is increased, the uniformity becomes improved. In particular, the uniformity within 4 % was attained in the entire plasma of 2 m in length in the condition of microwave power above 1000 W. This kind of uniform linear plasma production showed a threshold in the microwave power, above which the electron density becomes high enough above the cut-off density of microwave of 2.45 GHz. It was also found that the profile of electron density was adjustable by the short plunger. To be specific, the electron density measured at a fixed Z position showed a standing wave-like profile, indicating the short plunger has functions of standing wave generation as well as the phase-shifter as expected. Thus we conclude that the present method of large-scaled linear plasma production is quite advantageous for large area processing.