Research on Large-Scaled Line Plasma Production by Microwave

在太阳能电池薄膜CVD、平板显示器(FPD)以及各种大面积薄膜的表面改性等制造行业的材料加工中，长线形等离子体是不可避免的。在这项工作中，研究了一种新的大规模流水线等离子体生产方法。在该方法中，利用频率为2.45 GHz的微波功率在窄而平坦的矩形波导中产生长而均匀的线状等离子体。由于波导的宽度与截止条件非常接近，使得波导内部的微波波长极大地加长，为获得均匀的长线状高密度等离子体提供了条件。制作了长1.0 m和2.0 m、高5 mm的窄矩形波导，其宽度为61.5 mm~62.0 mm，非常接近微波的截止条件。该波导在顶面上有一个长长的线性缝隙天线，将微波功率发射到放电等离子体…中。更多1.0米和2.0米长的洞室。在波导端，用一个短的柱塞产生驻波并调整驻波的相位，从而产生均匀的等离子体。利用超长微波波长产生了气压为100mTorr到500mTorr的Ar等离子体。用朗缪尔探头对产生的等离子体参数进行了三维测量，电子密度的轴向分布非常平坦，在2m长的整个等离子体中，等离子体的均匀性在4%以内。研究还发现，在短柱塞位置，电子密度分布呈驻波状分布。具体来说，在固定的轴向位置测得的电子密度分布呈驻波状，表明短柱塞具有预期的驻波产生和移相器功能。在100mTorr气压和1kW的微波功率下，等离子体中的电子密度值表现出很高的值，高达1×10~(-3)cm~(-3)，表明等离子体的电子密度在微波截止条件以上是足够高的。实验证明，在微波作用下，轴向均匀等离子体产生存在一个阈值，超过该阈值，电子密度将充分高于微波截止密度。在这种情况下，微波功率进入短柱塞并被反射，产生驻波，从而可以极大地改善等离子体的均匀性。因此，该方法可以为长度大于2m、小于2m的大规模线性均匀等离子体生产提供有力的工具。

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