| In order to meet the demand for high-quality diamond applying in industrial application fields（such as mechanics, microelectronics and photoelectronics）,high-quality diamond films were prepared under high deposition pressure by microwave plasma chemical vapor deposition（MPCVD） with compressed rectangular waveguide. And the process of diamond deposition using CH4/H2, CH4/H2/O2,CH4/H2/Ar, and CH4/H2/O2/Ar as feed gas has been studied. And the uniform diamond films with low content of atmosphere carbon were synthesized by high deposition rate in this thesis.Firstly, the influence of pressure and methane concentration on deposition of diamond film by CH4/H2 plasma was studied. The uniformity of diamond films was researched. The results show that the radicals’ intensity increases with the increasing of pressure and methane concentration. And improving the deposition pressure is in favor of high-quality diamond film deposition with high growth rate. Under low deposition pressure（14 kPa）, only increasing the methane concentration is not useful for improving the growth rate of diamond films. In contrast, leading to reduce the crystallinity of diamond films and increase the content of amorphous carbon in diamond films. However, under high deposition pressure（31kPa）, the intensity ratios of C2, CH, Hγ to Hβ increased as a function of increasing methane concentration,which leading to improve the growth rate but depress the quality of film. At 31 kPa, in order to balance the quality and deposition rate of film, the methane concentration was fixed at 4.0 vol.%.Secondly, the effect of oxygen（0-0.56 vol.%） on high-quality diamond film growth using CH4/H2/O2 plasma was studied. The results indicate that the spectrum intensities of C2、CH and Hα decrease with the oxygen concentration increasing. While the intensity ratios of C2、CH to Hα also reduced as a function of increasing oxygen concentration. It is shown that the decrease of the absolute concentration of carbon radicals is attributed to the rise concentration of oxygen, while the relativeconcentration of carbon radicals to hydrogen atom is also reducing, which depressing the growth rate but improving the quality of diamond film. Furthermore, the OH radicals, role of etching, its intensities increase with the increase of oxygen concentration. Indicated that the improvement of OH concentration is also beneficial to reduce the content of amorphous carbon in diamond films.Thirdly, high growth rate deposition of polycrystalline diamond films with addition of argon.During the synthesis of diamond film by CH4（1.5 vol.%）/H2/Ar plasma, studied the relationship between the intensity, intensity ratio, special distribution of radicals in plasma and the deposition rate, quality, uniformity of diamond films. The results show that the addition of Ar is accelerated the dissociation rate of reaction gas CH4 and H2,and eventually increasing the spectrum intensities of Hα, Hβ, CH and C2. The deposition rate increases from 6.8 μm/h to 13.5 μm/h as a function of argon concentration was increased from 0.5 vol.% to 3.0 vol.%, but the film quality is degraded. The spectrum space diagnosis results show that the uniformity of CH, C2 radicals in plasma is not ideal, however, the ICH/IC2 intensity ratios in the central region tends to be consistent, which causes the thickness of film is uniform along the radial in that region. SEM characterization results show that the crystallite orientation of diamond films which deposited in 3.0 vol.% Ar changes from（110） to disorder,from the edge to the center region.At 25 kPa, using CH4（4.4 vol.%）/H2/O2（0.2 vol.%）/Ar（2.0 vol.%） plasma can successfully prepare high quality diamond film at a deposition rate of 18.2 μm/h. |
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