公开(公告)号：US10379448B2

公开(公告)日：2019-08-13

申请号：US15875156

申请日：2018-01-19

Applicant: ASML Netherlands B.V.

Inventor： Simon Gijsbert Josephus Mathijssen ,  Sander Bas Roobol ,  Nan Lin ,  Willem Marie Julia Marcel Coene ,  Arie Jeffrey Den Boef

IPC: G03B27/42 ,  G03F7/20 ,  G01B11/27 ,  G01N21/47 ,  G01N21/956 ,  G03F9/00

Abstract: Target structures such as overlay gratings (Ta and Tb) are formed on a substrate (W) by a lithographic process. The first target is illuminated with a spot of first radiation (456a, Sa) and simultaneously the second target is illuminated with a spot of second radiation (456b, Sb). A sensor (418) detects at different locations, portions (460x−, 460x+) of said first radiation that have been diffracted in a first direction by features of the first target and portions (460y−, 460y+) of said second radiation that have been diffracted in a second direction by features of the second target. Asymmetry in X and Y directions can be detected simultaneously, reducing the time required for overlay measurements in X and Y. The two spots of radiation at soft x-ray wavelength can be generated simply by exciting two locations (710a, 710b) in a higher harmonic generation (HHG) radiation source or inverse Compton scattering source.