The significant progress of SiC material development achieved in recent years opened the possibility to utilize unique features of SiC-based devices. However, advanced and SiC-specific modeling techniques have to be developed in order to optimize device properties and device fabrication steps. The goal of this work is, therefore, to introduce novel modeling approaches and extend simulation capabilities of thermal oxidation and dopant activation for SiC-based devices. In particular:
1. Oxidation growth rate coefficients for certain crystal orientations are missing or are inconsistent across the literature. A full set of oxidation coefficients will enable accurate simulations of SiC oxidation.
2. In order to be able to perform multi-dimensional simulations of SiC oxidation a direction-dependent oxidation model is necessary. A novel method, besides the currently available oxidation models, is needed in order to obtain unknown oxidation growth rates for arbitrary crystal directions.
3. The SiC oxidation models, which are typically expressed as differential equations, depend on initial conditions. Therefore, a detailed investigation of the initial oxidation stages of SiC is required to accurately determine initial oxide thicknesses.
4. Beside the SiC oxidation challenges, an accurate prediction of doping profiles in SiC is currently not available. The temperature-dependent activation rate of dopants must be investigated and an accurate modeling approach must be found.
5. The activation of dopants is not at all trivial, but rather highly dependent on the process parameters such as total doping concentration, annealing time, ambient gas concentration, and implantation temperature. Therefore, an appropriate approach to include various doping dependences in simulations is necessary.
One of the biggest challenges of this work is the lack of available experimental data, which does not provide the whole picture needed for investigations. In addition, the physics behind oxidation and activation mechanisms is not fully understood and impossible to predict without further investigations. Several phenomena are purely SiC-specific, therefore, the chemical mechanisms, physical processes, and computational models cannot be directly inherited from other semiconductor materials.
The research presented in this work was conducted within the scope of the Christian Doppler Laboratory for High Performance Technology Computer-Aided Design. The Christian Doppler Association funds cooperations between companies and research institutions pursuing application-orientated basic research. In this case, the cooperation was established between the Institute for Microelectronics at the TU Wien and Silvaco Inc., a company developing and providing electronic device automation and TCAD software tools.