Numerical modelling on dispersion behavior of particulate contamination induced by a moving operator in a semiconductor cleanroom: A eulerian-eulerian method

Contamination control in cleanrooms is crucial across various industries. In semiconductor manufacturing, operator-induced contamination presents a significant challenge, as it reduces the critical dimension. In this research, one comprehensive model describing contamination behaviour induced by operator motion was proposed, considering the moving operator as both a flow pattern changer and a contaminant source, combined with the number of particles accumulated (NPA) on the process instruments. To quantitatively characterise the transient contaminant dispersion behaviour caused by the operator, a Eulerian-Eulerian-based particle number density equation, integrated with overset mesh technology was employed. Our findings reveal that contamination dispersion behaviour is governed by convection and diffusion. The NPA on the side instruments at operator moving speeds at 0.5, 1, and 1.5 m/s were 4404.33, 8241.26, and 9384.41, respectively. And those of central instruments are 28463.75, 35848.60, and 43680.74 in corresponding cases. The largest reduction in influence on both the central and side instruments was found between cases with a maximum operator speed of 0.5 and 1.5 m/s, with NPA reaching reductions of 53.08 % and 34.84 % respectively. This indicates that the moving speed significantly affects contaminant dispersion.