Evaluating the Effects of Flow Rate Reduction on the Environmental Parameters of an Operational Cleanroom

This article provides results of measurements made to characterize the effects of lowering the HEPA filter air velocity in a operational semiconductor facility. Reduction of HEPA filter velocity can reduce energy consumption by lowering the power consumption of recirculation fans. Data were collected for the cleanroom base HEPA velocity condition. The same data set was collected for conditions of reduced HEPA filter air velocity. Comparison of the data distinguishes changes between different operational air velocities. There is significant variation in the measured values for HEPA filter velocity attributed to technique and facility parameters. When air velocity is reduced below an optimum value, airborne particle counts and variation in the counts increase. Lowered air velocity also affects total adsorbed vapors, the drain rate of charged wafers, and electrical power consumption of recirculation air handlers. For other measured parameters, a difference can be observed but the practical effect on the product can be considered negligible.