Lithographic apparatus and device manufacturing method
First Claim
Patent Images
1. An alignment system for aligning a substrate in a lithographic apparatus comprising:
- an illumination system configured to illuminate a phase grating on the substrate;
an imaging system configured to image diffracted light from said phase grating onto a reference grating substantially correctly at at least two distinct wavelengths; and
a field stop located at an intermediate plane and configured to adjust a field of illumination on said phase grating and said reference grating,wherein said imaging system includes an optical system configured to image said phase grating onto the intermediate plane.
1 Assignment
0 Petitions
Accused Products
Abstract
An off-axis alignment system in a lithographic projection apparatus uses broadband radiation to illuminate a phase grating on the wafer. The broadband radiation source may include fluorescent materials, e.g. Yag:Ce or ND:Yag crystals illuminated by excitation light.
17 Citations
22 Claims
-
1. An alignment system for aligning a substrate in a lithographic apparatus comprising:
-
an illumination system configured to illuminate a phase grating on the substrate; an imaging system configured to image diffracted light from said phase grating onto a reference grating substantially correctly at at least two distinct wavelengths; and a field stop located at an intermediate plane and configured to adjust a field of illumination on said phase grating and said reference grating, wherein said imaging system includes an optical system configured to image said phase grating onto the intermediate plane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. An alignment system for aligning a substrate in a lithographic apparatus comprising:
-
an illumination system configured to illuminate a phase grating on the substrate; an imaging system configured to image diffracted light from said phase grating onto a reference grating substantially correctly at at least two distinct wavelengths; a field stop configured to adjust a field of illumination on said phase grating and said reference grating; and a spatial filter, separate from said field stop, located at a pupil plane of said imaging system. - View Dependent Claims (17, 18)
-
-
19. An alignment system, for aligning a substrate in a lithographic apparatus comprising:
-
an illumination system configured to illuminate a phase grating on the substrate; an imaging system configured to image diffracted light from said phase grating onto a reference grating substantially correctly at at least two distinct wavelengths; a field stop configured to adjust a field of illumination on said phase grating and said reference grating; and a detection system configured to measure an intensity of the light from said phase grating, said detection system comprising a main signal detection branch and an alternative signal detection branch, said alternative signal detection branch being configured to measure a low intensity of said light from said phase grating. - View Dependent Claims (20)
-
-
21. An alignment system for aligning a substrate in a lithographic apparatus comprising:
-
an illumination system configured to illuminate a phase grating on the substrate; an imaging system configured to image diffracted light from said phase grating onto a reference grating substantially correctly at at least two distinct wavelengths; a field stop configured to adjust a field of illumination on said phase grating and said reference grating; and a detection system configured to, in a same scan of the phase grating or the reference grating with respect to the other, measure an intensity of the light from said phase grating to detect an alignment signal and, to detect a focus signal of said lithographic apparatus.
-
-
22. A method of aligning a substrate in a lithographic apparatus comprising:
-
illuminating a phase grating on a substrate; imaging light diffracted by said phase grating onto an intermediate plane; imaging light diffracted by said phase grating onto a reference grating substantially correctly at at least two distinct wavelengths; adjusting, at said intermediate plane, a field of illumination on said phase grating and said reference grating; and detecting light transmitted through said reference grating.
-
Specification