CFD-based Reaction Kinetics Modeling of Polysilicon Deposition in the Siemens Process

Project description

High-purity polysilicon is the starting material used in the manufacture of photovoltaic systems and microchips. It is produced industrially using the Siemens process, in which metallurgical silicon is converted into polysilicon through several process steps. A key step in the production process is chemical vapor deposition from a gas mixture of chlorosilanes and hydrogen onto the surface of electrically heated silicon rods at around 1000 °C. This is a highly energy-intensive process, making improvements in energy efficiency of great importance from both an economic and a sustainability perspective. At the same time, the product must also meet high quality requirements. To gain an in-depth understanding of the complex interactions between chemical reactions and transport phenomena in Siemens deposition, an experimentally validated, three-dimensional model is required.

To better understand the entire reaction mechanism and achieve acceptable predictive capability as well as numerical efficiency, the analysis and appropriate adaptation of the reaction kinetics model is an essential part of this project. Validation is carried out using laboratory- and production-scale experiments. The model is intended to serve as the basis for numerical process optimization, thereby contributing to a sustainable improvement in energy efficiency, product quality, and process stability in polysilicon production.