| 摘要 |
PROBLEM TO BE SOLVED: To keep a multistage stock device for use in a clean room clean or prevent dust on cassettes and dust made by friction between cassettes and partition plates from falling down onto lower cassettes or wafers. SOLUTION: On each side of a central transfer robot 1, a multistage cabinet is disposed wherein cassettes 2 are placed on partition plates 3 having openings for an airflow therethrough. A fan and filter unit 4 extending across the uppermost section blows clean air at a rate of 0.2 to 0.5 m/s. Another fan and filter unit 7 is disposed under the partition plate 3 at the bottom of each cabinet stage to inspire air within the associated stage and blow clean air to the next lower stage. The cabinet sides are separated from the outside environment by partitions. An equalized blowing rate of clean air of all the stages allows the vertical laminar flow made by the fan and filter units 7 at the top of the stages to hold the cassette storage sections clean.
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