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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In this work, silicon carbide (SiC) coatings were successfully grown by pulsed chemical vapor deposition (CVD). The precursors silicon tetrachloride (SiCl4) and ethylene (C2H4) were not supplied in a continuous flow but were pulsed alternately into the growth chamber with H2 as a carrier and a purge gas. A typical pulsed CVD cycle was SiCl4 pulse—H2 purge—C2H4 pulse—H2 purge. This led to growth of superconformal SiC coatings, which could not be obtained under similar process conditions using a constant flow CVD process. We propose a two-step framework for SiC growth via pulsed CVD. During the SiCl4 pulse, a layer of Si is deposited. In the following C2H4 pulse, this Si layer is carburized, and SiC is formed. The high chlorine surface coverage after the SiCl4 pulse is believed to enable superconformal growth via a growth inhibition effect.

Highly <111>-oriented 3C-SiC coatings with distinct surface morphology consisting of hexagonally shaped pyramidal crystals were prepared by chemical vapor deposition (CVD) using silicon tetrachloride (SiCl4) and toluene (C7H8) at T ≤ 1250 ℃ and p = 10 kPa. In contrast, similar deposition conditions, using methane (CH4) as 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 using C7H8 and CH4 as carbon precursors is explained via quantum chemical calculations of binding energies on various crystal planes. The adsorption energy of C6H6 on the SiC (111) plane was 6 times higher than that on the (110) surface. On the other hand, the CH3 exhibited equally strong adsorption on both planes. This suggests that the highly <111>-oriented 3C-SiC growth in the C7H8 process, where both C6H6 and CH3 are considered the main active carbon-containing film forming species, is due to the highly preferred adsorption on (111) planes, while the lower surface energy of the (110) plane controls the growth orientation in the CH4 process, in which only CH3 contributes to the film deposition.

In this work, silicon carbide coatings (SiC) were successfully grown by pulsed chemical vapor deposition (CVD). The precursors silicon tetrachloride (SiCl4) and ethylene (C2H4) were not supplied in a continuous flow, but were pulsed alternately into the growth chamber with H2 as a carrier and a purge gas. A typical pulsed CVD cycle was SiCl4 pulse – H2 purge – C2H4 pulse – H2 purge. This led to the growth of superconformal SiC coatings, which could not be obtained under similar process conditions using a constant flow CVD process. We propose a two-step mechanism for the SiC growth via pulsed CVD. During the SiCl4 pulse, a layer of Si is deposited. In the following C2H4 pulse, this Si layer is carburized, and SiC is formed. The high chlorine surface coverage after the SiCl4 pulse is believed to enable the superconformal growth via a growth inhibition mechanism.

for the assistance in measurements and fruitful discussions in the weekly group meetings.Special thanks are given to Georgios Rizothanasis, Emilie Lindblad and Sarah McIntyre for all the Friday evenings we have spent in exploring restaurants in Linköping. In the end, I would like to wholeheartedly thank my parents, 黃坤德 and 林淑貞, and my sisters, 黃琳宴 and 黃伊婷 for their unconditional and endless support from Taiwan.

SiC multilayer coatings were deposited via thermal chemical vapor deposition (CVD) using silicon tetrachloride (SiCl4) and various hydrocarbons under identical growth conditions, i.e. at 1100 ℃ and 10 kPa. The coatings consisted of layers whose preferred growth orientation alternated between random and highly <111>-oriented. The randomly oriented layers were prepared with either methane (CH4) or ethylene (C2H4) as carbon precursor, whereas the highly <111>-oriented layers were grown utilizing toluene (C7H8) as carbon precursor. In this work, we demonstrated how to fabricate multilayer coatings with different growth orientations by merely switching between hydrocarbons. Moreover, the success in depositing multilayer coatings on both flat and structured graphite substrates has strengthened the assumption proposed in our previous study that the growth of highly <111>-oriented SiC coatings using C7H8 was primarily driven by chemical surface reaction.