Experimental study of airflow and particle characteristics of a 300-mm POUP/LPU minienvironment system

This study examines the airflow and particle characteristics of a front opening unified pod/load port unit (FOUP/LPU) minienvironment system. The airflow and particle number were measured by using a three-dimensional ultrasonic anemometer and an He-Ne laser airborne particle counter, respectively. A large vortex is produced below an extracted wafer in the minienvironment. This vortex extends to the lower part of the minienvironment and reaches the door opener of the LPU. Particles produced on the moving parts of the LPU were carried to the back surface of the wafer, which were at the lowest position (the first wafer). How the open ratio of the perforated plate of the minienvironment affects the pressure difference between the minienvironment and surrounding environment and the airflow through the minienvironment was determined. The thoroughly elucidated information is useful for mitigating contamination when planning a fabrication line and designing a production tool.