| 摘要 |
There is disclosed a system for storing a projection mask of the type used for printing integrated circuit patterns on silicon wafers. A special cassette package permits the mask to be stored in a clean sealed environment. A delivery system transports the sealed cassette into an optical projection instrument wherein the cassette is opened and the mask advanced to the projection stage. After projection, the mask is returned and automatically sealed into the cassette. The cassette may be evacuated or, alternatively, filled with a clean gas. The mask sealed in the cassette can then be stored until its use is again required.
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