| 摘要 |
A multi-level reticle is described which comprises a multiplicity of integrated circuit mask patterns. The mask patterns are positioned in separate areas on the reticle. The reticle is adapted to be positioned in a projection stepper apparatus for projection of light through one of the areas of the reticle to project a mask pattern onto a substrate (e.g. a wafer) to form an image. The reticle is also adapted to be rotated about its center in a manner such that each of the other mask patterns on the reticle can be projected onto the substrate in registration with the image formed from projection of the first mask pattern onto the substrate. Typically the separate mask patterns are located in separate quadrants on the reticle when there are three or four mask patterns. When there are only two mask patterns, typically they are located in separate hemispheres on the reticle. By having multiple mask patterns on the same reticle, in separate areas on the reticle, it is possible to rotate the reticle in the projection stepper apparatus so that each mask pattern image projected is in registry with the images projected by the other mask patterns onto a wafer.
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