Patent ID: 8203692
Filing Date: 2012-06-19
Classification: G03B,G03F,H01L

Abstract:
1. An alignment mark on a substrate, the alignment mark comprising a periodic structure of a first plurality of first elements and a second plurality of second elements, the first elements and the second elements being arranged in an alternating repetitive sequence in a first direction, an overall pitch of the periodic structure being 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 comprising a first periodic sub-structure having a first sub-pitch; each second element comprising a second periodic sub-structure having a second sub-pitch; an optical property of the first element for interaction with a beam of radiation, being different from said optical property of the second element, the beam of radiation having a wavelength; and the overall pitch being larger than the wavelength, and each of the first sub-pitch and the second sub-pitch being smaller than the wavelength.