On the use of methane as a carbon precursor in Chemical Vapor Deposition of silicon carbide

Yazdanfar, Milan; Pedersen, Henrik; Sukkaew, Pitsiri; Ivanov, Ivan Gueorguiev; Danielsson, Örjan; Kordina, Olof; Janzén, Erik

doi:10.1016/j.jcrysgro.2013.12.033

Cited by 21 publications

(12 citation statements)

References 22 publications

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“…Thus, the kinetics of the hydrocarbon chemistry was less well investigated. Moreover, experimental results performed by our group 132 , showed that there were difference in the growth rates and surface roughness when different hydrocarbons were used as precursors. This led us to study the gas-phase kinetics of hydrocarbons presented in the literature.…”

Section: Chapter 4 Results and Summarymentioning

confidence: 99%

A Quantum Chemical Exploration of SiC Chemical Vapor Deposition

Sukkaew¹

2017

Linköping Studies in Science and Technology. Dissertations

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SiC is a wide bandgap semiconductor with many attractive properties. It has attracted particular attentions in the areas of power and sensor devices as well as biomedical and biosensor applications. This is owing to its properties such as large bandgap, high breakdown electric field, high thermal conductivities and chemically robustness. Typically, SiC homoepitaxial layers are grown using the chemical vapor deposition (CVD) technique. Experimental studies of SiC CVD have been limited to post-process measuring of the layer rather than in situ measurements. In most cases, the observations are presented in terms of input conditions rather than in terms of the unknown growth condition near the surface. This makes it difficult to really understand the underlying mechanism of what causes the features observed experimentally. With help of computational methods such as computational fluid dynamic (CFD) we can now explore various variables that are usually not possible to measure. CFD modeling of SiC CVD, however, requires inputs such as thermochemical properties and chemical reactions, which in many cases are not known. In this thesis, we use quantum chemical calculations to provide the missing details complementary to CFD modeling.We first determine the thermochemical properties of the halides and halohydrides of Si and C species, SiHnXm and CHnXm, for X being F, Cl and Br which were shown to be reliable compared to the available experimental and/or theoretical data. In the study of gas-phase kinetics, we combine ab initio methods and DFTs with conventional transition state theory to derive kinetic parameters for gas phase reactions related to Si-H-X species. Lastly, we study surface adsorptions related to SiC-CVD such as adsorptions of small C-H and Si-H-X species, and in the case of C-H adsorption, the study was extended to include subsequent surface reactions where stable surface products may be formed. iv SammanfattningSiC är ett halvledarmaterial med stort bandgap som har många attraktiva egenskaper. Det har fått särskilt mycket uppmärksamhet inom kraftkomponenter och sensorer, men också för tillämpningar inom biomedicin och biosensorer. Detta beror på materialets stora bandgap, förmågan att klara höga elektriska fält, goda värmeledningsförmåga och kemiska stabilitet. Epitaxiska skikt av SiC för kommersiella tillämpningar tillverkas med hjälp av kemisk ångdepo-sition (Chemical Vapor Deposition, CVD). Experimentella studier av SiC CVD begränsas till mätningar som görs i efterhand, snarare än under processens gång. För det mesta görs observationer med utgångspunkt från processens ingångsvärden istället för från de okända tillväxtförhållandena vid ytan. Detta gör det svårt att verkligen förstå de underliggande mekanismerna för de observerade experimentella resultaten. Med hjälp av beräkningsmetoder, såsom computational fluid dynamics (CFD) kan vi utforska olika variabler som vanligtvis inte går att mäta. Dock kräver CFD-modellering av SiC CVD ingångs-data i form av termokemiska egenskaper och kemiska reaktion...

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Section: Chapter 4 Results and Summarymentioning

confidence: 99%

A Quantum Chemical Exploration of SiC Chemical Vapor Deposition

Sukkaew¹

2017

Linköping Studies in Science and Technology. Dissertations

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“…A very high surface roughness is produced by the combination of SiH 4 +HCl and CH 4 , suggesting that these conditions are out of the narrow chemical window needed for deposition with this precursor combination. 7 The AFM images for the precursor combinations at C/Si = 0.6 are given in Figure 6. It can be seen that SiH 4 +HCl gives step bunched surfaces at this silicon rich condition, in line with previous findings.…”

Section: Resultsmentioning

confidence: 99%

“…Except for SiH 4 +HCl which gives very rough morphology with CH 4 at C/Si = 0.6, which is in line with our previous findings. 7 One could suggest that the lower surface roughness for SiCl 4 is due to a lower growth rate in the carbon limited chemistry. But while the growth rate indeed drops 29%, from around 105 μm/h at C/Si = 1 to 75 μm at C/Si = 0.6 when using SiCl 4 , the growth rate for SiHCl 3 drops 27%, from 110 to 80 μm/h for SiHCl 3 , and the growth rate for SiH 4 +HCl drops 37%, from 95 to 60 μm/h for SiH 4 +HCl.…”

Section: Resultsmentioning

confidence: 99%

Finding the Optimum Chloride-Based Chemistry for Chemical Vapor Deposition of SiC

Yazdanfar

Danielsson

Kordina

et al. 2014

ECS J. Solid State Sci. Technol.

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Chemical vapor deposition of silicon carbide with a chloride-based chemistry can be done using several different silicon and carbon precursors. Here, we present a comparative study of SiCl 4 , SiHCl 3 , SiH 4 +HCl, C 3 H 8 , C 2 H 4 and CH 4 in an attempt to find the optimal precursor combination. We find that while the chlorinated silanes SiCl 4 and especially SiHCl 3 give higher growth rate than natural silane and HCl, SiH 4 +HCl gives better morphology at C/Si around 1 and SiCl 4 gives the best morphology at low C/Si. Our study shows no effect on doping incorporation with precursor chemistry. We suggest that these results can be explained by the number of reaction steps in the gas phase chemical reaction mechanisms for producing SiCl 2 , which is the most important Si species, and by formation of organosilicons in the gas phase. As carbon precursor, C 3 H 8 or C 2 H 4 are more or less equal in performance with a slight advantage for C 3 H 8 , CH 4 is however not a carbon precursor that should be used unless extraordinary growth conditions are For the last, approximately ten years, chloride-based chemistry has been studied for chemical vapor deposition (CVD) of electronic grade SiC.1 The addition of Cl to the gas mixture circumvents condensation of silicon droplets above the substrate since the stronger Si-Cl bond (400 kJ/mol or 4.15 eV) 2 prevents Si-Si bonds (226 kJ/mol or 2.34 eV) 2 to form. This allows a higher precursor concentration in the CVD gas mixture which enables higher growth rates of epitaxial SiC layers; growth rates exceeding 100 μm/h are common, compared to the 5-10 μm/h usually obtained for the standard, non-chlorinated chemistry based on silane (SiH 4 ) and small hydrocarbons like ethylene (C 2 H 4 ) or propane (C 3 H 8 ). Cl-based CVD chemistry is therefore seen as an enabler of SiC power device technology 1 , where approximately 100 μm thick, low doped (10 14 cm −3 ), epitaxial layers are required for devices capable of blocking voltages on the order of 10 kV.Addition of Cl can be done either through the addition of HCl to the standard precursors, by using a chlorinated silane molecule (SiH x Cl y ) instead of SiH 4 , by using a chlorinated hydrocarbon (CH x Cl y ) instead of C 3 H 8 /C 2 H 4 or by using a single molecule (SiH x C y Cl z ). All these approaches have been reported to be successful and capable of growth rates exceeding 100 μm/h. 1 However, the optimal precursor for Clbased CVD of SiC is still not identified, despite ten years of research on Cl-based CVD chemistry. The single molecule approach has been successful, 3 but the inherent locked C/Si ratio hinders an efficient control of the doping incorporation 4 in SiC. Thermochemical studies suggests that the use of CH x Cl y is not likely an optimal route since the C-Cl bond is found to break, allowing Si-Cl bonds to form.5 Thus the CH x Cl y approach is probably a chemical detour. There have been attempts to compare data from various groups 1,6 but these comparisons are hampered by the fact that the data are acquired in differ...

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“…This is opposite to when CH 4 is used in chlorinated SiC CVD, where good growth conditions are confined to a narrower C/Si ratio window than when using C 2 H 4 as the C precursor. 28 The different rates at which growth species are formed from the precursors also suggests that combining different amounts of different precursors could be a way of controlling the spatial profile of the growth species impingement rate, and thereby the spatial profile of the C/Si impingement ratio.…”

Section: Discussionmentioning

confidence: 99%

Matching precursor kinetics to afford a more robust CVD chemistry: a case study of the C chemistry for silicon carbide using SiF₄ as Si precursor

et al. 2017

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Chemical Vapor Deposition (CVD) is one of the technology platforms forming the backbone of the semiconductor industry and is vital in the production of electronic devices. To upscale a CVD process from the lab to the fab, large area uniformity and high run-to-run reproducibility are needed. We show by a combination of experiments and gas phase kinetics modeling that the combinations of Si and C precursors with the most well-matched gas phase chemistry kinetics gives the largest area of of homoepitaxial growth of SiC. Comparing CH4, C2H4 and C3H8 as carbon precursors to the SiF4 silicon precursor, CH4 with the slowest kinetics renders the most robust CVD chemistry with large area epitaxial growth and low temperature sensitivity. We further show by quantum chemical modeling how the surface chemistry is impeded by the presence of F in the system which limits the amount of available surface sites for the C to adsorb.

Funding agencies: Knut & Alice Wallenberg Foundation (KAW) project Isotopic Control for Ultimate Material Properties; Swedish Foundation for Strategic Research project SiC - the Material for Energy-Saving Power Electronics [EM11-0034]; Swedish Government Strategic Research

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On the use of methane as a carbon precursor in Chemical Vapor Deposition of silicon carbide

Cited by 21 publications

References 22 publications

A Quantum Chemical Exploration of SiC Chemical Vapor Deposition

A Quantum Chemical Exploration of SiC Chemical Vapor Deposition

Finding the Optimum Chloride-Based Chemistry for Chemical Vapor Deposition of SiC

Matching precursor kinetics to afford a more robust CVD chemistry: a case study of the C chemistry for silicon carbide using SiF₄ as Si precursor

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On the use of methane as a carbon precursor in Chemical Vapor Deposition of silicon carbide

Cited by 21 publications

References 22 publications

A Quantum Chemical Exploration of SiC Chemical Vapor Deposition

A Quantum Chemical Exploration of SiC Chemical Vapor Deposition

Finding the Optimum Chloride-Based Chemistry for Chemical Vapor Deposition of SiC

Matching precursor kinetics to afford a more robust CVD chemistry: a case study of the C chemistry for silicon carbide using SiF4 as Si precursor

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Product

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Matching precursor kinetics to afford a more robust CVD chemistry: a case study of the C chemistry for silicon carbide using SiF₄ as Si precursor