| 摘要 |
The mask carrier assembly 6 for particle beam lithography supports a set of separate replaceable masks 12. The masks comprise a mask design field 15 and also reference marks used to align the masks to the substrate 11. Individual mask patterns corresponding to individual sub-fields can be combined on the substrate to give the total design required, and this design can be repeated by step and repeat exposure over the substrate (Fig 2). Different embodiments are described: these include a mask carrier with eight masks (Fig 3), sixteen masks (Fig 4), and masks formed on a single wafer (Figs 5,6). In this last embodiment the single wafer may be placed behind an aperture (32, Fig 10) in a screen (31,Fig 10) allowing any particular mask to be selected. The selected mask and the exposure aperture are aligned using alignment marks present around both the mask (24, Fig 9) and the aperture (34, Fig 10).
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