A numerical study on effective arrangement of fan-filter units in a semiconductor cleanroom: Control of hazardous gas leakage from a process instrument

Contamination control in cleanrooms is essential for maintaining high productivity across various industries. In semiconductor manufacturing environments, hazardous gas leaks from instruments can pose serious health risks to operators, especially during the preventive maintenance. In this study, the numerical simulations were performed to evaluate and optimize the fan filter unit (FFU) arrangement in a cleanroom, aiming to effectively manage hazardous hydrogen chloride (HCl) gas leakage during semiconductor instrument maintenance. To reflect the actual situation, the study incorporates leakage conditions from a reference, considering various thermal factors. The simulation results indicate that the FFU arrangement and coverage rate, which influence internal airflow under a fixed air change rate (ACH), are critical for hazardous leakage control during preventive maintenance. A quantitative and comprehensive analysis of the accumulation of leaked gas on the operator and instrument surfaces showed that the analysis score proposed in this research on the horizontal FFU array with 30% coverage was 0.44, which is minimum among different cases, indicating the best performance on controlling dispersion behaviour of the hazardous gas in the cleanroom during the preventive maintenance.