Research Areas

In the semiconductor industry, understanding fluid dynamics in rarefied conditions is crucial for processes like deposition and plasma generation, which occur in vacuum environments using rarefied gas free jets. While past understanding focused on overall gas concentrations, modern processes require detailed flow structure comprehension for success.

Research on supersonic jet flows has primarily focused on the near-field zone, lacking adequate quantitative analysis in the far-field zone due to measurement complexities. Flow characteristics, influenced by Knudsen and Mach numbers, undergo rapid changes in rarefied conditions, transitioning between turbulent, laminar, and rarefied gas regions.

In this study, our research group visualized 2D flow fields, including a circular free jet in a 1 torr vacuum environment, to analyze shockwave formation and near/far-field flow, aiming to establish reliable experimental foundations via acetone molecular tagging velocimetry (MTV). Results indicated the development of a stable annular viscous layer in the far-field zone, confirming a laminar flow regime. This research is crucial in the semiconductor industry, providing insights into the behavior of supersonic jets in vacuum environments, which are vital for optimizing semiconductor manufacturing processes.

Figure 1. Laser induced fluorescence (LIF) image of shockwave structure.