Mark position measuring apparatus and method, lithographic apparatus and device manufacturing method

Patent metadata

Field	Value
Publication number	US-9551939-B2
Application number	US-201314428565-A
Country	US
Kind code	B2
Filing date	Sep 23, 2013
Priority date	Oct 10, 2012
Publication date	Jan 24, 2017
Grant date	Jan 24, 2017

Abstract

An apparatus to measure the position of a mark, the apparatus including an illumination arrangement to direct radiation across a pupil of the apparatus, the illumination arrangement including an illumination source to provide multiple-wavelength radiation of substantially equal polarization and a wave plate to alter the polarization of the radiation in dependency of the wavelength, such that radiation of different polarization is supplied; an objective to direct radiation on the mark using the radiation supplied by the illumination arrangement while scanning the radiation across the mark in a scanning direction; a radiation processing element to process radiation that is diffracted by the mark and received by the objective; and a detection arrangement to detect variation in an intensity of radiation output by the radiation processing element during the scanning and to calculate from the detected variation a position of the mark in at least a first direction of measurement.

First claim

What is claimed is:

1. An apparatus comprising:
an illumination arrangement to direct radiation with an illumination profile across a pupil of the apparatus, the illumination arrangement comprising an illumination source to provide multiple-wavelength radiation of substantially equal polarization and a wave plate to alter the polarization of the radiation in dependency of the wavelength, such that radiation of different wavelengths having different polarization is supplied;
an objective lens to direct radiation on a mark using the radiation supplied by the illumination arrangement while scanning the radiation across the mark in a scanning direction;
a radiation processing element to process radiation that is diffracted by the mark and received by the objective lens; and
a detection arrangement to detect variation in an intensity of radiation output by the radiation processing element during the scanning and to calculate from the detected variation a position of the mark in at least a first direction of measurement.

2. The apparatus according to claim 1 , wherein the multiple-wavelength radiation and the wave plate are matched to each other, such that the multiple-wavelength radiation after passing the wave plate comprises radiation with a first linear polarization direction and radiation with a second linear polarization direction, the first polarization direction being orthogonal to the second linear polarization direction.

3. The apparatus according to claim 1 , wherein the radiation processing element is a self-referencing interferometer.

4. The apparatus according to claim 1 , wherein the mark comprises features periodic in at least a first direction and the illumination profile comprises radiation from source regions confined to a peripheral portion within a pupil of the objective lens, the source regions comprising at least first and second regions diametrically opposite one another with respect to an optical axis of the objective lens and being limited in angular extent with respect to the optical axis.

5. The apparatus according to claim 4 , wherein the illumination arrangement comprises a self-referencing interferometer configured to generate coherent radiation at the first and second source regions from radiation supplied to the illumination arrangement interferometer at a first source feed position, the first and second source regions being determined by the first source feed position, and wherein the wave plate is arranged downstream of the illumination arrangement interferometer.

6. The apparatus according to claim 5 , wherein the illumination arrangement further comprises a polarization adjuster to adjust a polarization of the radiation at one of the regions to match the polarization at the other position, when radiation at the first and second source regions emerges from the illumination arrangement interferometer with different polarizations, and wherein the polarization adjuster is arranged in between the illumination arrangement interferometer and the wave plate.

7. The apparatus according to claim 5 , wherein the illumination arrangement interferometer is further configured to generate radiation at the first or second source region from radiation supplied to the illumination arrangement at a second source feed position diametrically opposite to the first source feed position with respect to an optical axis of the illumination arrangement interferometer.

8. The apparatus according to claim 1 , comprising a second wave plate arranged between the objective lens and the radiation processing element, the second wave plate being configured to alter the polarization state of the radiation in dependency of the wavelength such that the radiation supplied by the objective lens after passing the second wave plate comprises multiple-wavelength radiation of substantially equal polarization.

9. The apparatus according to claim 1 , wherein the wave plate is formed by a birefringent crystal.

10. A lithographic apparatus arranged to transfer a pattern from a patterning device onto a substrate, the apparatus comprising a substrate table constructed to hold a substrate and an alignment sensor configured to measure the position of a mark relative to a reference frame of the lithographic apparatus, wherein the alignment sensor comprises the apparatus as claimed in claim 1 , and wherein the lithographic apparatus is arranged to control the transfer of a pattern onto the substrate by reference to the position of the mark measured using the measuring apparatus.

11. A method comprising:
providing multiple-wavelength radiation of substantially equal polarization;
altering the polarization of the radiation in dependency of wavelength;
illuminating a mark with radiation of different wavelengths having different polarizations and receiving radiation diffracted by the mark via an objective lens, the mark comprising features periodic in at least a first direction;
processing the diffracted radiation in a radiation processing element;
detecting variation in an intensity of radiation output by the radiation processing element while scanning the mark with the radiation; and
calculating from the detected variations a position of the mark in at least a first direction of measurement.

12. The method according to claim 11 , wherein radiation incident to the mark comprises radiation with a linear polarization substantially parallel to the first direction and linear polarization substantially perpendicular to the first direction.

13. The method according to claim 11 , wherein radiation incident to the mark comprises radiation of different polarization, and wherein the polarization of the radiation after passing the objective lens and prior to entering the radiation processing element is altered in dependency of wavelength such that multiple-wavelength radiation of substantially equal polarization is obtained.

14. A method of manufacturing a device in which a lithographic process is used to transfer a pattern from a patterning device onto a substrate, and wherein the transfer of a pattern onto the substrate is controlled by reference to the position of a mark measured using the method as claimed in claim 11 .

15. The method according to claim 11 , wherein the radiation processing element is a self-referencing interferometer.

16. The method according to claim 11 , comprising illuminating the mark with radiation from source regions confined to a peripheral portion within a pupil of the objective lens, the source regions comprising at least first and second regions diametrically opposite one another with respect to an optical axis of the objective lens and being limited in angular extent with respect to the optical axis.

17. The method according to claim 16 , further comprising generating coherent radiation at the first and second source regions from radiation supplied to an interferometer at a first source feed position, the first and second source regions being determined by the first source feed position, and wherein the wave plate is arranged downstream of the interferometer.

18. The method according to claim 17 , further comprising adjusting, using a polarization adjuster, a polarization of the radiation at one of the regions to match the polarization at the other position, when radiation at the first and second source regions emerges from the interferometer with different polarizations, and wherein the polarization adjuster is arranged in between the interferometer and the wave plate.

19. The method according to claim 17 , further comprising generating radiation

Assignees

• Asml Netherlands Bv
• Asml Holding Nv

Inventors

• Mathijssen Simon Gijsbert Josephus
• Den Boef Arie Jeffrey
• Drazkiewicz Stanley
• Kreuzer Justin Lloyd
• Nijmeijer Gerrit Johannes

Classifications

• G01B11/14

  for measuring distance or clearance between spaced objects or spaced apertures (G01B11/26 takes precedence; rangefinders G01C3/00) · CPC title

• G03F7/70141 Primary

  Illumination system adjustment, e.g. adjustments during exposure or alignment during assembly of illumination system · CPC title

• G03F9/7069 Primary

  Alignment mark illumination, e.g. darkfield, dual focus · CPC title

• G03F9/7088

  Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection · CPC title