Elementary gas‐phase reactions of radical species during chemical vapor deposition of silicon carbide using CH₃SiCl₃

Abstract

We established a kinetic model (the UT2017 model) for chemical vapor deposition of silicon carbide (SiC) from methyltrichlorosilane (CH3SiCl3, MTS)/H2, and quantitatively identified CH2SiCl3 as one of the SiC film‐forming species. In a previous study, we established a kinetic model (the UT2014 model), which reproduced the overall decomposition of MTS, but had not validated it in terms of radicals. In the present study, we first validated the UT2014 model by comparing it with the experimental results of radical production from MTS by Lemieux et al, without H2 present. The UT2014 model did not reproduce the production of CH2Cl from MTS at 1247°C. We found that the reactions of CH2SiCl3 isomerization to CH2ClSiCl2 and CH2ClSiCl2 decomposition to CH2Cl and SiCl2 were important for the production of CH2Cl from MTS. We re‐calculated those constants in pressure‐dependent formulas using the Rice‐Ramsperger‐Kassel‐Marcus method at the CBS‐QB3 level. These chemistries were added to the UT2014 model to yield the UT2017 model, which reproduced the production of radicals, including CH2Cl. Finally, using the UT2017 model, we simulated the gas composition under typical SiC chemical vapor infiltration conditions, which comprised mainly MTS and H2. A comparison of the simulation results with the partial pressure of film‐forming species in our previous report suggested that CH2SiCl3 was the possible film‐forming species of SiC from MTS/H2. For quantitative verification, we estimated the distribution of the partial pressure of CH2SiCl3 in our reactor while considering the consumption of CH2SiCl3 on the SiC surface. The values from this simulation result were almost identical to our experimental results for all positions in the reactor. Thus, we showed quantitatively that CH2SiCl3 is the film‐forming species of SiC.

Conformal and Stoichiometric Chemical Vapor Deposition of Silicon Carbide onto Ultradeep Heterogeneous Micropores by Controlling the Initial Nucleation Stage

“…For SiC-CVD from MTS/H 2 , the partial pressures of gas-phase species as a function of residence time were calculated via elementary reaction simulation using CHEMKIN-PRO, based on our developed UT2017 model. 27,28 3. FUNDAMENTALS: KINETIC STUDY ON CONTINUOUS FILM FORMATION OF SIC-CVD In this chapter, the surface reactions of SiC-CVD at the continuous film formation stage are discussed, where the number, η, and C of the film-forming species, were extracted experimentally.…”

“…Figure 8 shows the time-evolutional P of various gas-phase species calculated via the gas-phase elementary reaction simulation during SiC-CVD from MTS/H 2 , at T = 900 and 1000 °C, using our developed UT2017 model. 27,28 T profiles in the reactor are shown as dashed lines. The calculation does not include the deposition reaction of SiC on the surface, but is sufficient to determine the approximate C in the gas phase.…”

“…800 μm in diameter. For SiC-CVD from MTS/H 2 , the partial pressures of gas-phase species as a function of residence time were calculated via elementary reaction simulation using CHEMKIN-PRO, based on our developed UT2017 model. , …”

“…To design a conformal CVD process, a clear understanding of gas-phase and surface reaction kinetics and transportation of film-forming species is essential. New approaches for evaluation of the surface reaction kinetics of CVD (e.g., the Microcavity method , ) and the similar technique of atomic layer deposition (ALD) − have been developed using Si-based 3D test structures containing well-defined micrometer-scale trenches with ARs of over 100:1. − SiC-CVD has been conducted on Si microtrenches, and film-thickness decays along the trench depth have been analyzed to obtain the η values. − Combined with the time evolution of the gas-phase composition starting from an MTS/H 2 mixture, and calculated using elementary reaction simulations, − precise characterization of the surface reaction of SiC-CVD has been attempted. − ,, It has been shown that SiC-CVD involves three film-forming species: a high-η species (η ≈ 10 –2 ; probably CH 2 SiCl 3 ), a middle-η species (η ≈10 –4 ), and a low-η species (η ≈ 10 –6 ; MTS). ,, Furthermore, we have demonstrated conformal SiC-CVD via selective trapping of high-η species by using a sacrificial layer . Although the above experiments were conducted solely on heterogeneous Si surfaces due to the limited availability of test structures, the Si underlayers promoted the initial nucleation of SiC-CVD; thus kinetic studies on SiC-CVD during the continuous film-formation stages were successful.…”

Identifying the mechanism of formation of chlorinated silane polymer by‐products during chemical vapor infiltration of SiC from CH3SiCl3/H2

“…The calculated reaction rate constants are summarized in Table 1. The UT2019 model was devised by adding these data to the UT2017 model 20,21 …”