Multiscale investigation of the influence of surface morphology on thin film CVD

Barbato, Alessandro; Fiorucci, A.; Rondanini, M.; Cavallotti, Carlo

doi:10.1016/j.surfcoat.2007.04.071

Cited by 11 publications

(15 citation statements)

References 17 publications

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“…Though much computational work is present in the literature on this reaction, the reported results are mainly concerned with determining activation energies rather then pre‐exponential factors, which are however needed in a KMC simulation. Also, in our previous study 27 in which we simulated Si deposition from SiH 4 , we found that at low substrate temperatures when the surface is mostly covered by hydrogen, the film growth rate is higher than could be calculated using our Si deposition mechanism. We interpreted this as an indication that in those conditions hydrogen desorption mechanisms different and faster than those reported in the literature might be active.…”

Section: Elementary Processesmentioning

confidence: 62%

“…The adopted molecular model, shown in Fig. 5, is larger than the cluster used in our previous simulations of the Si(100)2 × 1 surface 27, 94 and is able to represent a relatively large portion of the surface, consisting of four parallel Si dimers. The cluster is composed of 60–61 Si atoms and 50–52H atoms, depending on the simulated process.…”

Section: Elementary Processesmentioning

confidence: 99%

“…The challenges associated with the development of a multiscale model are related to the consistent coupling of the different single scale models, which is straightforward if one of the models is independently used to determine some of the parameters used by the other, but more complex if the coupling is bi‐directional, as is the case if the two models share a common boundary of a physical domain. In the latter case, several strategies have been proposed to couple consistently the two models, based either on the continuity of fluxes at the interface 20, 27, or on the definition of an effective reactivity function 7, 24.…”

Section: Introductionmentioning

confidence: 99%

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Challenges of introducing quantitative elementary reactions in multiscale models of thin film deposition

Barbato

Cavallotti

2010

phys. stat. sol. (b)

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The implementation of detailed surface kinetic mechanisms describing the thin film growth dynamics into models of chemical vapor deposition (CVD) reactors has been a challenge for many years. In this article we review the literature concerning the study of the dynamics of the Si(100)2×1 surface and introduce a multiscale model that captures the main features of its reactivity. The model combines the results of ab initio calculations with an atomistic description of the Si surface, obtained using a 3D-kineticMonte Carlo (KMC)model that explicitly accounts for the 2×1 surface reconstruction and the formation and diffusion of Si dimers on a hydrogenated surface. At the atomistic scale, we determined pre-exponential factors and activation energies of hydrogen desorption reactions proceeding through the 2H, 3H, and 4H mechanisms. The calculated kinetic constants were embedded in the KMC model and used to simulate literature TPD experimental data. The simulations were used to fit the activation energies of hydrogen desorption reactions, which showed that DFT calculations performed with B3LYP functionals are likely to overestimate hydrogen desorption energies by up to 9 kcalmol^-1, which was confirmed by successive ab initio calculations. Two examples of the solution of the KMC model in conjunction with a reactor scale model are provided, in which the coupling was performed adopting both a hierarchic and a two-way coupling strategy.We found that in the plasma deposition of nanocrystalline silicon performed at low substrate temperatures the growth proceeds through a layer-by-layer mechanism on a surface almost completely covered by hydrogen. The application of the same model to the simulation of the thermal CVD of Si showed that at intermediate growth temperatures, when the hydrogen surface concentration is high, a new hydrogen desorption mechanism, in which Si adatoms play an important role, is active. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

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Section: Elementary Processesmentioning

confidence: 62%

Section: Elementary Processesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Challenges of introducing quantitative elementary reactions in multiscale models of thin film deposition

Barbato

Cavallotti

2010

phys. stat. sol. (b)

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“…A 3 dimensional, grand-canonical, kinetic Monte Carlo (3D-KMC) method was implemented in order to reproduce the microscopic surface evolution during the growth process following the theory outlined in our previous publications [14,15]. The 3D-KMC code characteristic features are direct tracking of real-time and rejection-free choice of the random transition.…”

Section: Microscale Simulationsmentioning

confidence: 99%

“…KMC calculations were performed over 5 different equidistant points of the reactive surface. A stable convergent scheme is obtained by incorporating information about the jacobian contribution at the reactor-nodes boundary, as discussed more in detail in our previous publication [14,15].…”

Section: Microscale Simulationsmentioning

confidence: 99%

A Multiscale Model of The Low-Temperature CVD of Silicon

Cavallotti¹,

Barbato²

2008

ECS Trans.

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Among the semiconductor materials, silicon stands out for its technological, industrial, and scientific relevance. Its growth process has been widely studied, theoretically and experimentally, so that it's surface and gas phase kinetics are mostly known. In this work this knowledge was exploited to develop a 3D Kinetic Monte Carlo model that, combined consistently with a detailed fluid dynamic analysis of a CVD reactor and ab initio simulations of relevant surface processes, was used to investigate the surface and gas phase dynamics active during the film growth. The proposed mathematical model is thus able to link information coming from the atomic scale, such as the diffusion of hydrogen and silicon adatoms and dimers, with the surface microstructural evolution (density and shape of islands), and, finally, with the reactor operating parameters, such as pressure, temperature and gas phase composition.

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Reactivity of Silicon Surfaces in the Presence of Adsorbed Hydrogen and Chlorine

Cavallotti¹

2010

Chemical Vapor Deposition

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The desorption of hydrogen and hydrogen chloride from Si surfaces is the rate-determining step of the low temperature CVD of silicon from both hydrogenated and chlorinated precursors. Thus, in order to model the deposition process, the rate of these reactions must be known to a high level of accuracy. In this work, the surface desorption kinetics of H 2 and HCl from the Si(100)2 T 1 surface is investigated by modeling the surface through clusters of various dimensions (up to 60 Si atoms) and determining the reaction energies at the B3LYP, and coupled cluster methodology with inclusion of single, double and a perturbative estimation of triple excitations (CCSD(T)) levels. The investigated mechanisms are the pairwise intradimer and the 4H-2H reaction pathways. The desorption activation energy (57.4 kcal mol À1 ) and adsorption barriers (15.9 kcal mol À1 ) calculated for H 2 for the 4H and 2H pathways are in good agreement with experimental data, confirming that these are the H 2 main desorption and adsorption routes. The reaction mechanism of HCl is different to that of H 2 . The calculations in fact indicate that the less activated desorption pathway (65.0 kcal mol À1) is the intradimer mechanism, followed by the 2H pathway (67.1 kcal mol À1 ), which might thus compete with the intradimer pathway at low surface coverage. The HCl adsorption barrier on Si dimers is small (0.6 À 4.8 kcal mol À1), confirming the high reactivity of HCl with Si surfaces.

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Multiscale investigation of the influence of surface morphology on thin film CVD

Cited by 11 publications

References 17 publications

Challenges of introducing quantitative elementary reactions in multiscale models of thin film deposition

Challenges of introducing quantitative elementary reactions in multiscale models of thin film deposition

A Multiscale Model of The Low-Temperature CVD of Silicon

Reactivity of Silicon Surfaces in the Presence of Adsorbed Hydrogen and Chlorine

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