For the emerging semiconductor material silicon carbide (SiC) used in high power devices, chemical vapor deposition (CVD) is the most prominent method to create the electrically active SiC epitaxial layers in the device. The process of growing such epitaxial layers is to use a hydrocarbon and silane diluted in hydrogen flow through a hot chamber where chemical reactions take place in such manner that Si and C finally deposit on the surface creating epitaxial SiC. The addition of chlorine (Cl) to the process has been thoroughly investigated due to its ability to reduce homogeneous nucleation in the gas phase attributed to the stronger Si-Cl bond compared to the Si-Si bond. In this thesis the fluorinated chemistry has been investigated, since the Si-F bond is even stronger than the Si-Cl bond and the fluorinated chemistry for SiC CVD has remained poorly understood.

Using SiF₄ as Si precursor in growth experiments combined with thermal equilibrium calculations of gas phase composition and quantum chemical computations of the surface chemistry first the silicon chemistry in the CVD process has been probed. It is shown that while growth rates on the order of 35 µm/h can be achieved with a fluorinated chemistry, the deposition chemistry is very sensitive to the mass flows of the precursors and not as robust as the chlorinated CVD chemistry which routinely yields 100 µm/h over wide conditions. By using the position for the onset of epitaxial growth along the gas flow direction as a new measurable, together with modeling, it is conclude that SiF is the main Si growth species with SiHF as a minor Si species contributing to growth.

The carbon chemistry in a fluorinated SiC CVD process has been probed by a similar approach. Here it is found that the slow kinetics of the SiF4 molecule needs to be matched by a carbon precursor with comparable slow kinetics. It is shown that methane is a suitable carbon precursor in combination with SiF₄.

Before a fluorinated CVD chemistry can be adopted in device processing, the effect of fluorine on the dopant incorporation must be understood since dopant incorporation is of paramount importance in semiconductor manufacturing. Dopant incorporation studies for n-type doping with N using N₂ and p-type doping with Al using TMAl in fluorinated CVD of homoepitaxial SiC are presented. It is found to be possible to control the doping in SiC epitaxial layers when using a fluorinated CVD chemistry for both n- and p-type material using the C/Si ratio as in standard SiC CVD. However, large area doping uniformity seems to be a challenge for a fluorinated CVD chemistry, most likely due to the very strong Si-F and Al-F bonds. It is found that no additional optically or electrically active defects are created due to the use of fluorine in the CVD process.

Finally, the fluorinated chemistry is compared to the chlorinated and brominated chemistries for SiC CVD and an overall model for halogen addition to SiC CVD is presented.

SiC is a wide bandgap semiconductor with many attractive properties. It hasattracted particular attentions in the areas of power and sensor devices as wellas biomedical and biosensor applications. This is owing to its properties suchas large bandgap, high breakdown electric field, high thermal conductivitiesand chemically robustness. Typically, SiC homoepitaxial layers are grownusing the chemical vapor deposition (CVD) technique. Experimental studiesof SiC CVD have been limited to post-process measuring of the layer ratherthan in situ measurements. In most cases, the observations are presented interms of input conditions rather than in terms of the unknown growth conditionnear the surface. This makes it difficult to really understand the underlyingmechanism of what causes the features observed experimentally. Withhelp 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 thermochemicalproperties and chemical reactions, which in many cases are not known. In thisthesis, we use quantum chemical calculations to provide the missing detailscomplementary to CFD modeling.

We first determine the thermochemical properties of the halides and halohydridesof Si and C species, SiHnXm and CHnXm, for X being F, Cl and Brwhich were shown to be reliable compared to the available experimentaland/or theoretical data. In the study of gas-phase kinetics, we combine ab initiomethods and DFTs with conventional transition state theory to derive kineticparameters for gas phase reactions related to Si-H-X species. Lastly, westudy surface adsorptions related to SiC-CVD such as adsorptions of small CHand Si-H-X species, and in the case of C-H adsorption, the study was extendedto include subsequent surface reactions where stable surface productsmay be formed.