| 摘要 |
A method and a test-structure for determining an offset between lithographic masks are described. In one embodiment, an image of a first mask is provided in a patterning layer on a substrate. The image of the first mask comprises a first set of lines, each line separated by a distance D. An image of a second mask is then provided in the patterning layer. The image of the second mask comprises a second set of lines, each line also separated by the distance D. The second set of lines interlays the first set of lines to form a grating with a distance L between each of the lines of the first set of lines and the respective corresponding lines of the second set of lines. The offset between the first and second masks is determined by calculating the difference between the distance L and a predetermined value K, where 0<K<D. In a specific embodiment, K=½D.
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