| Summary: | 碩士 === 大同大學 === 材料工程學系(所) === 93 === Deposition of amorphous carbon and amorphous carbon-nitrogen films by RF-plasma enhanced chemical vapor deposition was studied. The effects of deposition parameters, including N2/CH4 ratio, total flow rate, working pressure, RF power, deposition time and the self bias voltage, will be discussed. We investigate the effects of the parameters on the deposition rate, the structure and the hardness of the films by analyzing the weight and thickness of the films, raman spectroscopy, x-ray photoelectron spectroscopy (XPS) and nanoindentation. The experimental results show that the deposition rate decreases with increasing the N2/CH4 ratio and deposition time, and with decreasing the total flow rate and the working pressure. The deposition rate also increases as the range of the self bias voltage increases from 250 V-300 V to 335 V-365 V. As N2/CH4＜0.75, the deposition rate increases with increasing the RF power. On the contrary, the deposition rate is higher for lower RF power as N2/CH4≧0.75. Analysis of raman spectrum shows that the structure of the films has no obvious change with the total flow rate and deposition time. The characteristics of the films tend to be graphite like with increasing the N2/CH4 ratio and RF power, and with decreasing the working pressure. The characteristics of the films tend to be diamond like as the range of the self bias voltage increases from 250 V-300 V to 335 V-365 V. The position of G band is between 1540 cm-1 and 1580 cm-1. XPS analysis shows that the maximum N/C ratio of the carbon-nitrogen is 0.07 while the film was deposited under a RF power of 200 W, a total flow rate of 30 sccm and a working pressure of 0.3 torr. As N2/CH4 ratio increases, the relative quantity of sp3C-C decreases. XPS analysis also indicates that the oxygen content decreases when the sample was sputtered with Ar+ for 1 min. It is also shown that sp2C-C is preferentially sputtered. The results of nanoindentation are consistent with the results of the structure analysis by raman spectroscopy. In other word, the hardness increases when the ratio of sp3C-C/sp2C-C increases. No obvious change of hardness with the total flow rate and deposition time was found. However, the hardness decreases as the N2/CH4 ratio and RF power are raised, and as the working pressure is decreased. The hardness also increases as the range of the self-bias voltage increases from 250 V-300 V to 335 V-365 V. The hardness of all of the films investigated in this study is between 7 GPa and 19 GPa. Although the hardness decreases as nitrogen content increases, the films still possess the hardness of the DLC films under certain deposition parameters.
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