Modeling of the role of atomic hydrogen in heat transfer during hot filament assisted deposition of diamond

Abstract

The temperature and atomic hydrogen concentration profiles in a hot filament type diamond deposition reactor were determined experimentally and theoretically to demonstrate that the reaction of atomic hydrogen on the substrate surface plays an important role in the heating of the substrate. For a given filament temperature, the substrate temperature in helium was significantly lower than that in either pure hydrogen or 1% methane-hydrogen atmospheres. The presence of small amounts of methane in hydrogen did not have any significant effect in influencing the shape of the atomic hydrogen concentration profile. In the space between the filament and the substrate, the concentration field is established mainly due to the diffusive mixing of the atomic hydrogen with the molecular hydrogen and other species in the gas phase. Homogeneous chemical reactions in the gas phase do not significantly affect the atomic hydrogen concentration distribution in this region.

Production and Detection of H Atoms and Vibrationally Excited H2 Molecules in CVD Processes

“…Film precursors adsorbed on the growing surface move to find energetically favorable sites, leading to the formation of a crystallized structure. Local heating may also play a role in diamond deposition,9, 16 but it can be more important in the deposition of silicon‐related films, since the typical substrate temperature is rather low (between 600 and 800 K) in silicon deposition. The temperature for diamond growth is typically over 1000 K. The lower substrate temperatures are necessary to retain the quality of silicon‐related films 14.…”

Numerical simulation of HFCVD process used for diamond growth

“…The streamlines are slightly compressed near the filament while streamlines are relatively spread out in the direction of the substrate. This may suggest that the gas flow has an insignificant influence on the temperature distribution and that conduction is the primary factor in establishing the temperature field [7]. Fig.…”

Fabrication of smooth diamond films on SiO2 by the addition of nitrogen to the gas feed in hot-filament chemical vapor deposition

“…Hydrogen acts as an efficient catalyst for hybridization of the existing free bonds of the already-deposited carbon atoms on the substrate so that the arriving carbon atoms may easily form C-C sp 3 bonds. 3,4 However, this process often produces a film of columnar structure with grain facets ending in ͑111͒ planes, which results in a film of very high roughness.…”