Model for the Formation of Silicon Carbide from the Pyrolysis of Dichlorodimethylsilane in Hydrogen: II, Silicon Carbide Formation from Silicon and Methane

Abstract

A model is developed for the deposition of silicon carbide from the pyrolysis of dichlorodimethylsiane in hydrogen, in a tubular reactor at temperatures from 700° to 1100°C and 1.013 × 105 Pa (1 atm) pressure. Concentration of dichlorodimethylsilane varied from 2 to 8 vol%. Gas chromatography was used to determine the volatile products of reaction, and gravimetric analysis was used to determine the total silicon and silicon carbide deposition on the tube. The model developed based on the experimental data that assumes the following chemical reactions: The rate constants derived from a nonlinear regression analysis are reported.

CVD of SiC from Methyltrichlorosilane. Part I: Deposition Rates

“…A fraction of hydrogen is flowing through a saturator (2) for the uptake of MTS. This flow and that of pure hydrogen are mixed in a mixing chamber (3). After flowing through the reactor (4), the product stream passes a cold trap (7), held at a temperature of ±20 C, an absorption column (8) filled with a 1:1 mixture of isopropanol and glycol, another absorption column filled with a solution of NaOH (9), and a drying column filled with CaCl 2 (10).…”

“…[1,2] Deposition rate, gas phase composition as well as composition and structure of the deposit were determined in a single study. [3] Deposition rates have been studied using a thermobalance [8,9,12,13,34,35] or a flow reactor. [1±5,7,19,29,36] In both cases hot-wall [1±5,7±9,12,13,19,29,34,36] or cold-wall reactors [21] were used.…”

“…[21] A few studies have been concerned with modeling the gas phase composition based on thermodynamics [8,9,27,28] or kinetics of elementary reactions. [24±26,29] Energy dispersive X-ray (EDX) analysis [11] and elemental analysis [2,3] are the most frequently used techniques to determine the composition of the deposit. Structure and growth orientation of the deposit have been analyzed using X-ray diffraction (XRD).…”

“…[27] In one study, a model to simulate SiC deposition from DMS and hydrogen was applied. [3,4] In most cases, reduced models were discussed. Methane and methyl have generally been assumed to be the carbon source for SiC in a temperature range up to about 1100 C. SiC deposition from a carbosilane, CH 2 =SiCl 2 , was discussed in one study.…”

Chemical vapor deposition of SiC at different molar ratios of hydrogen to methyltrichlorosilane

“…Fig.7(e) shows that there is a little of HCl in the gas phase during the pyrolysis of MTS below 950 . During ℃ the consecutive reaction process, the increase of the concentration of HCl with the temperature trends to be more rapid above 950 because of the reactions of ℃ SiHCl 3 , SiCl 4 and CH 4 produced in the gas phase during the dissociation of MTS, as the following reactions (7) and (8): SiHCl 3 →SiCl 2 ••+HCl (7) SiCl 2 ••+CH 4 →ClSiCH 3 ••+HCl (8) It is obvious that the concentration of HCl at n(H 2 )/n(MTS)=8 is higher than that at n(H 2 )/n(MTS)=4, which can be explained by reaction (6). When the amount of H 2 is increased, reaction (6) is promoted, which results in large amount of HCl in the gas phase.…”