Generation methods for high pressure plasmas to be operated in wide parameter ranges and their applications.

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Plasma sources which can be operated at atmospheric pressure range are of much interest for applications to various surface treatment technologies. Therefore, the methods for realizing stable glow discharges over larger areas or volumes have been investigated enthusiastically. The aim of our research is to develop a new plasma source which can be operated stably in a wide pressure range including the atmospheric pressure with higher plasma density.In the first step, we have designed a new type of plasma source with an integrated structure of microplasmas arranged in a plane, which is categorized as a dielectric barrier discharge (DBD) scheme. Then, its characteristics have been investigated in a comparison with a conventional parallel-plate system. On the way, we developed a method for the quantitative measurement of metastable He^*(2^3S_1) atoms by using a laser absorption technique at the wavelength of 1.08 μm. We developed also a unique method for the measurement of plasma density with the transmittance characteristics of microwaves of mm-range, by which the electron densities were measured not only in He plasmas but also in N_2 and air plasmas. As the results of those diagnostics, it has been clarified that the plasma density obtained in our new plasma source is higher than that in a conventional source by about an order of magnitude even though the operating voltage is much smaller and also the stability range is wider.In the second step, the source has been applied to the chemical vapor deposition of SiO_2 films by using TEOS as the source material. It turned out that the flows of the diluent and source gases strongly influence the deposition rate and the uniformity under the atmospheric condition. We are trying to optimize the deposition condition by using a simulation tool for the gas flow to realize better results.