Particle characteristics of 300-mm minienvironment (FOUP and LPU)

We have clarified the particle characteristics of a front opening unified pod (FOUP) and a load port unit (LPU) experimentally. The FOUP and LPU are fundamental components in 300-mm minienvironment systems. Our experiments showed the following. The particles per wafer pass (PWP) increases with the number of airborne particles outside the enclosure. The particle characteristics of FOUP and LPU can be improved by reducing the FOUP door-opening speed. The PWP of the wafer in the top slot is remarkably high. By optimizing the FOUP door-opening speed, we can achieve FOUP and LPU particle characteristics similar to those of a standard mechanical interface (SMIF) system.