Experimental investigation of the interaction of a pair of supersonic jets in near vacuum

Semiconductor processes are traditionally carried out in rarefied gas environments due to various reasons including purity requirements, deposition efficiency, and plasma generation. Although the overall conditions are near vacuum, gas jets are utilized for various processes within vacuum process chambers. The jets that supply process gases are arranged in various configurations, such as showerhead arrays, to provide uniform flow. In single wafer process chambers, the jets are mostly located at the top of the chamber, with the distance to the wafer being more than 100 times the jet diameter. Therefore, it is necessary to understand the jet merging process and resulting far-field flow structure at near vacuum conditions. Previous studies have mainly focused on single jet shockwaves in the near field, with limited analysis of multi-jet merging in the far field. This study analyzes the merging of a pair of jets utilizing acetone molecular tagging velocimetry (MTV). The results will provide a baseline for further studies of multi-jets in near vacuum environments.