公开(公告)号：US20230251407A1

公开(公告)日：2023-08-10

申请号：US18003301

申请日：2021-06-17

Applicant: ASML Netherlands B.V.

Inventor： Derick Yun Chek Chong ,  Wouter Joep ENGELEN ,  Vyacheslav KACHKANOV ,  Vahid MOHAMMADI ,  Pieter Cristiaan DE GROOT

IPC: G02B5/18 ,  G03F7/20

CPC classification number: G02B5/1866 ,  G02B5/1857 ,  G03F7/70158 ,  G03F7/706 ,  G03F7/7085 ,  G02B2207/107

Abstract: A transmissive diffraction grating for a phase-stepping measurement system for determining an aberration map for a projection system comprises an absorbing layer. The diffraction grating is for use with radiation having a first wavelength (for example (EUV radiation). The absorbing layer is provided with a two-dimensional array of through-apertures. The absorbing layer is formed from a material which has a refractive index for the radiation having the first wavelength in the range 0.% to 1.04.