Highly ⟨111⟩-oriented 3C-SiC coatings with a distinct surface morphology consisting of hexagonally shaped pyramidal crystals were prepared by chemical vapor deposition (CVD) using silicon tetrachloride (SiCl 4 ) and toluene (C 7 H 8 ) at T ≤ 1250 °C and p tot = 10 kPa. In contrast, similar deposition conditions, with methane (CH 4 ) as the carbon precursor, resulted in randomly oriented 3C-SiC coatings with a cauliflower-like surface of SiC crystallites. No excess carbon was detected in the highly ⟨111⟩-oriented 3C-SiC samples despite the use of aromatic hydrocarbons. The difference in the preferred growth orientation of the 3C-SiC coatings deposited by using C 7 H 8 and CH 4 as the carbon precursors was explained via quantum chemical calculations of binding energies on various crystal planes. The adsorption energy of C 6 H 6 on the SiC (111) plane was 6 times higher than that on the (110) plane. On the other hand, CH 3 exhibited equally strong adsorption on both planes. This suggested that the highly ⟨111⟩-oriented 3C-SiC growth with C 7 H 8 as the carbon precursor, where both C 6 H 6 and CH 3 were considered the main active carbon-containing film forming species, was due to the highly preferred adsorption on the (111) plane, while the lower surface energy of the (110) plane controlled the growth orientation in the CH 4 process, in which only CH 3 contributed to the film deposition.

The approaches to conformal and superconformal deposition developed by Abelson and Girolami for a low-temperature, low-pressure chemical vapor deposition (CVD) setting relevant for electronic materials in micrometer or submicrometer scale vias and trenches, are tested here in a high-temperature, moderate pressure CVD setting relevant for hard coatings in millimeter-scale trenches. Conformal and superconformal deposition of polycrystalline silicon carbide (SiC) can be accomplished at deposition temperatures between 950 and 1000 °C with precursor partial pressure higher than 20 Pa and an optional minor addition of HCl as a growth inhibitor. The conformal deposition at low temperatures is ascribed to slower kinetics of the precursor consumption along the trench depth, whereas the impact of high precursor partial pressure and addition of inhibitor is attributable to surface site blocking. With the slower kinetics and the site blocking from precursor saturation leading the growth to nearly conformal and the possibly preferential inhibition effect near the opening than at the depth, a superconformal SiC coating with 2.6 times higher thickness at the bottom compared to the top of a 1 mm trench was achieved.

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