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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.

Abstmct-An optimal design approach for Surface Acoustic Wave (SAW) filters is presented. First of all, the structural design of a three-IDT type SAW filter, which consists of three interdigital transducers (IDT) and two reflectors, is formulated as a combinatorial o p timization problem. In order t o simulate the frequency response of the SAW filter, the least equivalent circuit model of IDT is employed. Then, a new local search technique based on the k-degree-neighborhood is prcposed and applied to the optimization problem successfully. The proposed local search is applicable generally t o the structural design of various SAW devices.

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