| Capacitively coupled plasma(CCP) has been widely used in thin film deposition and plasma etching due to its simple device, which can be easily controlled and could produce large plasma. Plasma enhanced chemical vapour deposition(PECVD) is a preparation technique to achieve the growth of thin film materials, in which chemical reactions among gases containing film components are produced by glow discharge plasma. In photovoltaic industry, silicon-based thin films play a very important role, especially silicon oxynitride(SiOxNy) thin film, which integrated the advantages of silicon oxide(SiO2) thin film and silicon nitride (Si3N4) thin film. Due to their excellent properties, including good photoelectrical characteristics, mechanical property, chemical stability and low stress, SiOxNy films have been widely applied in optical and microelectronic fields as graded index films or antireflection coatings. Meanwhile, SiOxNy films are also used as the reflection film of solar cells in order to get high utilization. So, SiOxNy thin film has broad application prospects and the research on it has the vital significance. However, in continuous discharges, high-energy ions produced will damage to the substrate and the photoelectric of the film is poor in this condition. By contrast, high quality of SiOxNy film can be obtained in pulse modulation discharge with more flexible parameters. Nevertheless, apart from pure gas discharges, such studies on mixture gas discharge is relatively insufficient due to the complexity of both the chemical components and the reaction process. There is still an increasing need for deep descriptions and predictions of silicon discharge, especially for pulsed radio frequency plasma. In this paper, the behavior of silicon plasma mixed with SiH4, N2 and O2 driven by time modulated voltage have been carried out by using a one-dimensional fluid model.Chapter I and Chapter II introduce the related background knowledge and the one dimensional fluid mechanics model separately, and give a detailed summary of the related parameters in the calculation.Chapter III emphasizes on the effect of pulse parameters on SiH4/N2/O2 capacitive coupling plasma discharge characteristics. Our results demonstrate great influence of pulse duty cycle and modulation frequency on the plasma parameter. When the averaged density of the deposition power is kept constant, the electron density at the center of the discharge is inversely proportional to the duty cycle, and more higher plasma density can be achieved. If the rf voltage is fixed, the electron density is proportional to the duty cycle, but decreases with the increasing modulated frequencies. Meanwhile, the electron temperature changes obviously under different duty cycles or modulated frequencies, and shows a quite dynamic behavior when the duty cycle or the modulated frequency is smaller. The electronegativity of the plasma keeps almost constant in the bulk plasma and shows great change near the plates. Furthermore, lower ion energy will be obtained under the same deposition power density by reducing the modulated frequency of duty cycle, leading to less damage to the substrate. The change of mean velocity and flux of the positive ions at the powered plate under pulsed discharge will re-adjusted the other prameters, making the film deposition process more flexible. The impacts of other discharge parameters on the plasma, such as air pressure, plate width and rf voltage are investigated at the fixed duty cycle and modulation frequency. The plasma density can be effectively improved with higher rf voltage, larger pressure or more wide plate width. Small periodic change of electron temperature at the center of the plates occurs with the various of pressure and plate width. Furthermore, ion energy can be reduced because of the intensified collisions between particles when the pressure or the width of the plates increases. Meanwhile, higher rf voltage can offer more energy to ions.It is concluded that while choosing proper duty cycle, modulated frequency or other discharge parameters, high plasma density and deposition power density can be provided in pulse modulated discharge, and the ion energy can be lowered effectively. Thus, damage on the substrate caused by ion bombardment can be reduced in order to get high quality thin films.
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