| 摘要 |
An alignment mark on a substrate includes a periodic structure of a plurality of first elements and a plurality of second elements. The elements are arranged in an alternating repetitive sequence in a first direction. An overall pitch of the periodic structure is equal to a sum of a width of the first element and a width of the second element in the first direction. Each first element has a first periodic sub-structure with a first sub-pitch and each second element has a second periodic sub-structure with second sub-pitch. An optical property of the first element for interaction with a beam of radiation having a wavelength lambda is different from the optical property of the second element. The overall pitch is larger than the wavelength lambda, and each of the first and the second sub-pitch is smaller than the wavelength.
|
