Untersuchung des Prozessabluftreinigungssystems einer Epitaxieanlage unter Berücksichtigung sicherheitstechnischer Aspekte

The reliable operation of exhaust gas treatment systems in the semiconductor industry is essential to ensure the continuous and safe functioning of production processes, particularly in bottleneck operations such as SiC epitaxy. Technical failures in these systems can lead to production downtime and are often associated with significant risks to human health and the environment. Severe corrosion accompanied by noticeable heat generation was observed in the exhaust pipelines downstream of a burner-scrubber system connected to a SiC epitaxy reactor. The aim of this study was to investigate the underlying causes of these phenomena and to derive relevant safety implications. To this end, the composition of the exhaust gas from the epitaxy reactor and the physicochemical processes within the burner-scrubber system were determined through theoretical analyses. In addition, deposit samples collected upstream and downstream of the burner-scrubber system, as well as emissions measurements, were examined. Both theoretical considerations and experimental investigations indicate the formation of SiO2 particles within the burner and an HCl mist in the scrubber, leading to acidic deposits in the exhaust pipelines following gas treatment. The deposits also showed significant amounts of HNO3, attributed to NOx formation during combustion. These substances caused corrosion of the original pipeline material. As corrective measures, the use of pure water in the quench to prevent HCl mist formation, as well as the installation of a downstream NOx scrubber to further improve exhaust gas quality, were proposed. Additionally, further investigation of the vapor formed when deposits upstream of the burner-scrubber system come into contact with water is recommended, in order to better assess safety risks during maintenance operations.