Uniform and rapid nucleation of diamond via bias-assisted hot filament chemical vapor deposition
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Uniform and rapid nucleation of diamond via bias-assisted hot filament chemical vapor deposition Yan Chen, Feng Chen, and E. G. Wanga) State Key Laboratory for Surface Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603-5, Beijing 100080, People’s Republic of China (Received 27 December 1995; accepted 14 September 1997)
A new method was developed to obtain high density, uniform diamond nuclei via bias-assisted hot filament chemical vapor deposition. A negative bias was applied between a mesh (installed above the filament) and the substrate to produce abundant uniform ions at the growth surface. Raman spectroscopy, scanning electron microscopy, and Auger electron microscopy were used to analyze the films obtained. The results show that a layer of diamond film with a nucleation density of 109ycm2 can be obtained after 10 min deposition under 1 Torr.
I. INTRODUCTION
Because of its potential applications in high temperature semiconductor devices, the attainment of high nucleation density of diamond in low pressure chemical vapor deposition (CVD) on a defect free hetero-substrate surface is one of the most exciting challenges. Even if we obtain ultrathin continuous film demanded by the microelectrical industry, our understanding of the initial formation of diamond nucleation is still primitive. Recently, negative substrate bias1,2 has been employed in microwave plasma CVD (MPCVD) environment to reach a nucleation density of 109 –1011ycm2 . By using a similar method in the nucleation stage, Jiang et al.3 and Wolter et al.4 have deposited heteroepitaxial diamond (100) film on mirror-smooth Si(100), respectively. Positive bias in MPCVD is also regarded as an effective method to enhance the diamond nucleation.5 The easily achieved high diamond nucleation density in MPCVD environments via bias was examined due to the existence of abundant ions in the plasma. However, the situation is quite different in a hot filament CVD (HFCVD) apparatus. Recently, Stubhan et al.6 and Chen et al.,7 respectively, reported heteroepitaxial nucleation and growth of diamond(100) on Si(100) by HF-CVD while the uniformity of the films has not been given attention. The results of Zhu et al.8 showed that the diamond nuclei were obtained only at the periphery of the substrate and almost no nuclei were obtained in the center region when the negative bias was applied only between the filament and the substrate. A similar result was reported by Chen et al.,7 which was also observed in our earlier experiments.9 How to obtain uniform, high density diamond nucleation via bias assisted HF-CVD is still an open question in this field. a)
Author to whom correspondence should be addressed. e-mail: [email protected]
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J. Mater. Res., Vol. 13, No. 1, Jan 1998
In this paper, we propose the application of negative bias in HF-CVD apparatus to obtain uniform diamond nuclei on the substrate rapidly. An intense glow discharge was formed over the substrate surface in our arrangement; a rel
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