Research on Large-Scaled Line Plasma Production by Microwave

点击翻译按钮获取中文摘要

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 linear plasma. Since the width of waveguide is very close to the cutoff condition, the wavelength of microwave inside the guide is extremely lengthened, providing a condition of long linear 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 61.5 mm-62.0 mm which is very closed to the cut-off condition of microwave. The waveguide has a long linear slot antenna on the top surface to launch the microwave power into the discharge plasma … More chamber of 1.0 and 2.0 m in length. At the end of wave guide, a short plunger was quipped to produce a standing microwave and to adjust the phase of the standing wave, hence the uniformity of the plasma thus produced. The plasmas of Ar at the pressures of 100 mTorr to 500 mTorr were produced by employing an extremely long microwave wavelength. The parameters of plasma thus produced were three-dimensionally measured by a Langmuir probe.The axial profile of electron density was extremely flat and the plasma uniformity was within 4 % in the entire plasma over 2 m long. It was also found that the profile of electron density showed a standing wave like profile for the short plunger position. To be specific, the electron density measured in a fixed axial position showed a standing wave-like profile, indicating the short plunger has functions of standing wave generation and the phase-shifter as expected. The value of electron density in the plasma showed a very high value, as high as 1x10^<12> cm^<-3> at the pressure of 100mTorr and the microwave power of 1 kW, indicating that the plasma electron density is adequately high above the cut-off condition of microwave. It was experimentally verified that the axially uniform plasma production has a threshold in microwave, above which the electron density becomes adequately higher than the microwave cut-off density. In these conditions, the microwave power comes onto the short plunger and is reflected, producing a standing wave, and thus the plasma uniformity can be improved very much. It is concluded thus that the present method can provide a powerful tool of large-scaled linear uniform plasma production in length more than 2 m. Less