Direct Nitridation Of Silicon Nitrogen Kinetics And Mechanism Study

Silicon Nitride (normally Si3N4) has been widely used in such fields as micro-electronics and optoelectronics as a promising film material because of its excellent property. Many researches have been made on silicon nitride, especially on preparation for it with all kinds of CVD(Chemical Vapor Deposition). But the growth mechanism and kinetics of direct-nitridation in nitrogen are not investigated in detail, especially few work has been done on direct-nitridation of silicon wafer in nitrogen during heat treatment. Some researchers even think that silicon wafer cann't react with nitrogen during heat treatment (<1300 )because of its inertia. The direct-nitridation of silicon wafer in nitrogen is very important because it involves in silicon wafer's heat treatment, IC technics and pulling monocrystal in nitrogen. In this paper, the condition of direction-nitridation, the kinetics and nitridation mechanism are discussed in experiment and theoretically.Current researches, applications, preparation and structure of Si3N4 are summarized in this paper. A new conclusion is drawn that silicon wafer can react with nitrogen at the temperature higher than 1100 and in super-pure nitrogen by direct-nitridation of silicon at the temperature from 800 to 1200 . The prepared silicon nitride samples are tested by XPS(X-ray photoelectron spectroscopy), SEM (scanning electron microscopy), Optical Microscopy, XRD(X-Ray Diffraction) and EDX(Energy Dispersive X-Ray analysis).Samples are prepared at 1100 and 1200 for different time from 5 minutes to 4 hours to study direct-nitridation kinetics. The thickness of the silicon nitride films is measured by Single-Spot thickness System produced by Filmetrics Co. LTD. The direct-nitridation kinetics curve is attained and the maximum thickness of the silicon nitride film is about 50nm. At same time macroscopical and microcosmic mathematical model of nitridation are investigated.In this paper the thermodynamics of direct-nitridation, effect of temperature and nitrogen ambience on nitridaton and self-diffusion are discussed in the theory of physical chemistry in detail. The procedure of direct-nitridation in nitrogen and the growth mechanism are analyzed.In the end the direct-nitridation of silicon dioxides in nitrogen is investigated with EDX and Optical Microscopy. The effect of oxygen on nitridation of silicon by nitrogen is discussed in thetheory of physical chemistry.